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29a2b744 | 1 | \input texinfo @c -*-texinfo-*- |
d390cad1 | 2 | @c Copyright 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 |
f886dc0f | 3 | @c Free Software Foundation, Inc. |
18fae2a8 | 4 | @c |
29a2b744 | 5 | @c %**start of header |
18fae2a8 | 6 | @c makeinfo ignores cmds prev to setfilename, so its arg cannot make use |
1d7c3357 | 7 | @c of @set vars. However, you can override filename with makeinfo -o. |
18fae2a8 RP |
8 | @setfilename gdb.info |
9 | @c | |
361daf65 | 10 | @include gdb-cfg.texi |
18fae2a8 RP |
11 | @c |
12 | @ifset GENERIC | |
13 | @settitle Debugging with @value{GDBN} | |
14 | @end ifset | |
15 | @ifclear GENERIC | |
1d7c3357 | 16 | @settitle Debugging with @value{GDBN} (@value{TARGET}) |
18fae2a8 | 17 | @end ifclear |
af215b1a | 18 | @clear RENAMED |
29a2b744 | 19 | @setchapternewpage odd |
29a2b744 RP |
20 | @c %**end of header |
21 | ||
ed447b95 | 22 | @iftex |
51b65b74 | 23 | @c @smallbook |
fe715d06 | 24 | @c @cropmarks |
ed447b95 RP |
25 | @end iftex |
26 | ||
29a2b744 RP |
27 | @finalout |
28 | @syncodeindex ky cp | |
29 | ||
fe715d06 RP |
30 | @c readline appendices use @vindex |
31 | @syncodeindex vr cp | |
32 | ||
0cb95a9c | 33 | @c !!set GDB manual's edition---not the same as GDB version! |
b90b2ac2 | 34 | @set EDITION Fifth |
0cb95a9c RP |
35 | |
36 | @c !!set GDB manual's revision date | |
b90b2ac2 | 37 | @set DATE April 1998 |
29a2b744 | 38 | |
9c3ad547 | 39 | @c THIS MANUAL REQUIRES TEXINFO-2 macros and info-makers to format properly. |
29a2b744 | 40 | |
b7becc8f | 41 | @ifinfo |
ed447b95 RP |
42 | @c This is a dir.info fragment to support semi-automated addition of |
43 | @c manuals to an info tree. zoo@cygnus.com is developing this facility. | |
b7becc8f RP |
44 | @format |
45 | START-INFO-DIR-ENTRY | |
af215b1a | 46 | * Gdb: (gdb). The @sc{gnu} debugger. |
b7becc8f RP |
47 | END-INFO-DIR-ENTRY |
48 | @end format | |
49 | @end ifinfo | |
18fae2a8 | 50 | @c |
70b88761 | 51 | @c |
70b88761 | 52 | @ifinfo |
af215b1a | 53 | This file documents the @sc{gnu} debugger @value{GDBN}. |
70b88761 | 54 | |
0cb95a9c | 55 | |
b90b2ac2 | 56 | This is the @value{EDITION} Edition, @value{DATE}, |
af215b1a VM |
57 | of @cite{Debugging with @value{GDBN}: the @sc{gnu} Source-Level Debugger} |
58 | for @value{GDBN} Version @value{GDBVN}. | |
29a2b744 | 59 | |
b90b2ac2 | 60 | Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998 |
f886dc0f | 61 | Free Software Foundation, Inc. |
70b88761 RP |
62 | |
63 | Permission is granted to make and distribute verbatim copies of | |
64 | this manual provided the copyright notice and this permission notice | |
65 | are preserved on all copies. | |
66 | ||
67 | @ignore | |
68 | Permission is granted to process this file through TeX and print the | |
69 | results, provided the printed document carries copying permission | |
70 | notice identical to this one except for the removal of this paragraph | |
71 | (this paragraph not being relevant to the printed manual). | |
72 | ||
73 | @end ignore | |
74 | Permission is granted to copy and distribute modified versions of this | |
75 | manual under the conditions for verbatim copying, provided also that the | |
d55320a0 RP |
76 | entire resulting derived work is distributed under the terms of a |
77 | permission notice identical to this one. | |
70b88761 RP |
78 | |
79 | Permission is granted to copy and distribute translations of this manual | |
d55320a0 | 80 | into another language, under the above conditions for modified versions. |
70b88761 | 81 | @end ifinfo |
1041a570 | 82 | |
70b88761 | 83 | @titlepage |
18fae2a8 | 84 | @title Debugging with @value{GDBN} |
af215b1a | 85 | @subtitle The @sc{gnu} Source-Level Debugger |
18fae2a8 | 86 | @ifclear GENERIC |
a64a6c2b | 87 | @subtitle (@value{TARGET}) |
18fae2a8 | 88 | @end ifclear |
70b88761 | 89 | @sp 1 |
b90b2ac2 | 90 | @subtitle @value{EDITION} Edition, for @value{GDBN} version @value{GDBVN} |
0cb95a9c | 91 | @subtitle @value{DATE} |
1fe1c717 | 92 | @author Richard M. Stallman and Roland H. Pesch |
70b88761 RP |
93 | @page |
94 | @tex | |
95 | {\parskip=0pt | |
18fae2a8 | 96 | \hfill (Send bugs and comments on @value{GDBN} to bug-gdb\@prep.ai.mit.edu.)\par |
ed447b95 | 97 | \hfill {\it Debugging with @value{GDBN}}\par |
70b88761 | 98 | \hfill \TeX{}info \texinfoversion\par |
af215b1a | 99 | \hfill doc\@cygnus.com\par |
70b88761 RP |
100 | } |
101 | @end tex | |
102 | ||
103 | @vskip 0pt plus 1filll | |
b90b2ac2 | 104 | Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998 |
f886dc0f | 105 | Free Software Foundation, Inc. |
6b51acad RP |
106 | @sp 2 |
107 | Published by the Free Software Foundation @* | |
6c9638b4 FF |
108 | 59 Temple Place - Suite 330, @* |
109 | Boston, MA 02111-1307 USA @* | |
6b51acad RP |
110 | Printed copies are available for $20 each. @* |
111 | ISBN 1-882114-11-6 @* | |
af215b1a | 112 | |
70b88761 RP |
113 | Permission is granted to make and distribute verbatim copies of |
114 | this manual provided the copyright notice and this permission notice | |
115 | are preserved on all copies. | |
116 | ||
117 | Permission is granted to copy and distribute modified versions of this | |
118 | manual under the conditions for verbatim copying, provided also that the | |
d55320a0 RP |
119 | entire resulting derived work is distributed under the terms of a |
120 | permission notice identical to this one. | |
70b88761 RP |
121 | |
122 | Permission is granted to copy and distribute translations of this manual | |
d55320a0 | 123 | into another language, under the above conditions for modified versions. |
70b88761 RP |
124 | @end titlepage |
125 | @page | |
126 | ||
70b88761 | 127 | @ifinfo |
4eb4cf57 | 128 | @node Top |
18fae2a8 | 129 | @top Debugging with @value{GDBN} |
29a2b744 | 130 | |
af215b1a | 131 | This file describes @value{GDBN}, the @sc{gnu} symbolic debugger. |
29a2b744 | 132 | |
b90b2ac2 | 133 | This is the @value{EDITION} Edition, @value{DATE}, for @value{GDBN} Version |
af215b1a | 134 | @value{GDBVN}. |
70b88761 RP |
135 | |
136 | @menu | |
18fae2a8 | 137 | * Summary:: Summary of @value{GDBN} |
18fae2a8 RP |
138 | @ifclear BARETARGET |
139 | * Sample Session:: A sample @value{GDBN} session | |
140 | @end ifclear | |
b0157555 | 141 | |
18fae2a8 RP |
142 | * Invocation:: Getting in and out of @value{GDBN} |
143 | * Commands:: @value{GDBN} commands | |
144 | * Running:: Running programs under @value{GDBN} | |
29a2b744 RP |
145 | * Stopping:: Stopping and continuing |
146 | * Stack:: Examining the stack | |
147 | * Source:: Examining source files | |
148 | * Data:: Examining data | |
18fae2a8 RP |
149 | @ifclear CONLY |
150 | * Languages:: Using @value{GDBN} with different languages | |
151 | @end ifclear | |
152 | @ifset CONLY | |
1d7c3357 | 153 | * C:: C language support |
18fae2a8 | 154 | @end ifset |
1d7c3357 | 155 | @c remnant makeinfo bug, blank line needed after two end-ifs? |
18fae2a8 | 156 | |
18fae2a8 RP |
157 | * Symbols:: Examining the symbol table |
158 | * Altering:: Altering execution | |
93918348 | 159 | * GDB Files:: @value{GDBN} files |
18fae2a8 RP |
160 | * Targets:: Specifying a debugging target |
161 | * Controlling GDB:: Controlling @value{GDBN} | |
162 | * Sequences:: Canned sequences of commands | |
18fae2a8 | 163 | @ifclear DOSHOST |
af215b1a | 164 | * Emacs:: Using @value{GDBN} under @sc{gnu} Emacs |
18fae2a8 | 165 | @end ifclear |
b0157555 | 166 | |
18fae2a8 | 167 | * GDB Bugs:: Reporting bugs in @value{GDBN} |
da24340c RP |
168 | * Command Line Editing:: Facilities of the readline library |
169 | * Using History Interactively:: | |
af215b1a VM |
170 | @c @ifset NOVEL |
171 | @c * Renamed Commands:: | |
172 | @c @end ifset | |
1d7c3357 | 173 | @ifclear PRECONFIGURED |
af215b1a | 174 | * Formatting Documentation:: How to format and print @value{GDBN} documentation |
18fae2a8 | 175 | * Installing GDB:: Installing GDB |
18fae2a8 | 176 | @end ifclear |
b0157555 | 177 | |
18fae2a8 RP |
178 | * Index:: Index |
179 | @end menu | |
18fae2a8 | 180 | @end ifinfo |
70b88761 | 181 | |
4eb4cf57 | 182 | @node Summary |
18fae2a8 | 183 | @unnumbered Summary of @value{GDBN} |
70b88761 | 184 | |
18fae2a8 | 185 | The purpose of a debugger such as @value{GDBN} is to allow you to see what is |
70b88761 | 186 | going on ``inside'' another program while it executes---or what another |
1041a570 | 187 | program was doing at the moment it crashed. |
70b88761 | 188 | |
18fae2a8 | 189 | @value{GDBN} can do four main kinds of things (plus other things in support of |
1041a570 | 190 | these) to help you catch bugs in the act: |
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191 | |
192 | @itemize @bullet | |
193 | @item | |
194 | Start your program, specifying anything that might affect its behavior. | |
195 | ||
196 | @item | |
197 | Make your program stop on specified conditions. | |
198 | ||
199 | @item | |
200 | Examine what has happened, when your program has stopped. | |
201 | ||
202 | @item | |
203 | Change things in your program, so you can experiment with correcting the | |
204 | effects of one bug and go on to learn about another. | |
205 | @end itemize | |
206 | ||
18fae2a8 | 207 | @ifclear CONLY |
9934dce8 | 208 | You can use @value{GDBN} to debug programs written in C or C++. |
22b5dba5 RP |
209 | @c "MOD2" used as a "miscellaneous languages" flag here. |
210 | @c This is acceptable while there is no real doc for Chill and Pascal. | |
9934dce8 RP |
211 | @ifclear MOD2 |
212 | For more information, see @ref{Support,,Supported languages}. | |
213 | @end ifclear | |
214 | @ifset MOD2 | |
215 | For more information, see @ref{C,,C and C++}. | |
216 | ||
3f73b7c8 | 217 | Support for Modula-2 and Chill is partial. For information on Modula-2, |
2ae6d007 | 218 | see @ref{Modula-2,,Modula-2}. There is no further documentation on Chill yet. |
3f73b7c8 | 219 | |
b1955f0b | 220 | Debugging Pascal programs which use sets, subranges, file variables, or nested |
22b5dba5 | 221 | functions does not currently work. @value{GDBN} does not support |
b1955f0b | 222 | entering expressions, printing values, or similar features using Pascal syntax. |
af215b1a | 223 | |
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224 | @end ifset |
225 | @ifset FORTRAN | |
11e7b867 | 226 | @cindex Fortran |
3ff8a96f | 227 | @value{GDBN} can be used to debug programs written in Fortran, although |
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228 | it does not yet support entering expressions, printing values, or |
229 | similar features using Fortran syntax. It may be necessary to refer to | |
230 | some variables with a trailing underscore. | |
09934a2b | 231 | @end ifset |
18fae2a8 | 232 | @end ifclear |
70b88761 RP |
233 | |
234 | @menu | |
ed447b95 | 235 | * Free Software:: Freely redistributable software |
b80282d5 | 236 | * Contributors:: Contributors to GDB |
70b88761 RP |
237 | @end menu |
238 | ||
4eb4cf57 | 239 | @node Free Software |
93928b60 | 240 | @unnumberedsec Free software |
1041a570 | 241 | |
af215b1a VM |
242 | @value{GDBN} is @dfn{free software}, protected by the @sc{gnu} |
243 | General Public License | |
1041a570 | 244 | (GPL). The GPL gives you the freedom to copy or adapt a licensed |
70b88761 RP |
245 | program---but every person getting a copy also gets with it the |
246 | freedom to modify that copy (which means that they must get access to | |
247 | the source code), and the freedom to distribute further copies. | |
248 | Typical software companies use copyrights to limit your freedoms; the | |
249 | Free Software Foundation uses the GPL to preserve these freedoms. | |
250 | ||
251 | Fundamentally, the General Public License is a license which says that | |
29a2b744 | 252 | you have these freedoms and that you cannot take these freedoms away |
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253 | from anyone else. |
254 | ||
4eb4cf57 | 255 | @node Contributors |
70b88761 RP |
256 | @unnumberedsec Contributors to GDB |
257 | ||
af215b1a | 258 | Richard Stallman was the original author of GDB, and of many other @sc{gnu} |
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259 | programs. Many others have contributed to its development. This |
260 | section attempts to credit major contributors. One of the virtues of | |
261 | free software is that everyone is free to contribute to it; with | |
262 | regret, we cannot actually acknowledge everyone here. The file | |
af215b1a | 263 | @file{ChangeLog} in the @value{GDBN} distribution approximates a blow-by-blow |
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264 | account. |
265 | ||
266 | Changes much prior to version 2.0 are lost in the mists of time. | |
267 | ||
268 | @quotation | |
269 | @emph{Plea:} Additions to this section are particularly welcome. If you | |
93918348 | 270 | or your friends (or enemies, to be evenhanded) have been unfairly |
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271 | omitted from this list, we would like to add your names! |
272 | @end quotation | |
273 | ||
274 | So that they may not regard their long labor as thankless, we | |
356bc67b | 275 | particularly thank those who shepherded GDB through major releases: |
f886dc0f SS |
276 | Stan Shebs (release 4.14), |
277 | Fred Fish (releases 4.13, 4.12, 4.11, 4.10, and 4.9), | |
356bc67b SS |
278 | Stu Grossman and John Gilmore (releases 4.8, 4.7, 4.6, 4.5, and 4.4), |
279 | John Gilmore (releases 4.3, 4.2, 4.1, 4.0, and 3.9); | |
280 | Jim Kingdon (releases 3.5, 3.4, and 3.3); | |
281 | and Randy Smith (releases 3.2, 3.1, and 3.0). | |
af215b1a | 282 | As major maintainer of @value{GDBN} for some period, each |
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283 | contributed significantly to the structure, stability, and capabilities |
284 | of the entire debugger. | |
70b88761 | 285 | |
6b51acad | 286 | Richard Stallman, assisted at various times by Peter TerMaat, Chris |
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287 | Hanson, and Richard Mlynarik, handled releases through 2.8. |
288 | ||
1d7c3357 | 289 | @ifclear CONLY |
af215b1a | 290 | Michael Tiemann is the author of most of the @sc{gnu} C++ support in GDB, |
70b88761 | 291 | with significant additional contributions from Per Bothner. James |
af215b1a | 292 | Clark wrote the @sc{gnu} C++ demangler. Early work on C++ was by Peter |
70b88761 | 293 | TerMaat (who also did much general update work leading to release 3.0). |
1d7c3357 | 294 | @end ifclear |
70b88761 | 295 | |
af215b1a | 296 | @value{GDBN} 4 uses the BFD subroutine library to examine multiple |
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297 | object-file formats; BFD was a joint project of David V. |
298 | Henkel-Wallace, Rich Pixley, Steve Chamberlain, and John Gilmore. | |
70b88761 | 299 | |
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300 | David Johnson wrote the original COFF support; Pace Willison did |
301 | the original support for encapsulated COFF. | |
70b88761 | 302 | |
d390cad1 SS |
303 | Brent Benson of Harris Computer Systems contributed DWARF 2 support. |
304 | ||
70b88761 RP |
305 | Adam de Boor and Bradley Davis contributed the ISI Optimum V support. |
306 | Per Bothner, Noboyuki Hikichi, and Alessandro Forin contributed MIPS | |
1041a570 | 307 | support. |
356bc67b SS |
308 | Jean-Daniel Fekete contributed Sun 386i support. |
309 | Chris Hanson improved the HP9000 support. | |
310 | Noboyuki Hikichi and Tomoyuki Hasei contributed Sony/News OS 3 support. | |
311 | David Johnson contributed Encore Umax support. | |
312 | Jyrki Kuoppala contributed Altos 3068 support. | |
313 | Jeff Law contributed HP PA and SOM support. | |
314 | Keith Packard contributed NS32K support. | |
315 | Doug Rabson contributed Acorn Risc Machine support. | |
316 | Bob Rusk contributed Harris Nighthawk CX-UX support. | |
317 | Chris Smith contributed Convex support (and Fortran debugging). | |
318 | Jonathan Stone contributed Pyramid support. | |
319 | Michael Tiemann contributed SPARC support. | |
320 | Tim Tucker contributed support for the Gould NP1 and Gould Powernode. | |
321 | Pace Willison contributed Intel 386 support. | |
322 | Jay Vosburgh contributed Symmetry support. | |
70b88761 | 323 | |
c338a2fd RP |
324 | Rich Schaefer and Peter Schauer helped with support of SunOS shared |
325 | libraries. | |
70b88761 | 326 | |
af215b1a | 327 | Jay Fenlason and Roland McGrath ensured that @value{GDBN} and GAS agree about |
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328 | several machine instruction sets. |
329 | ||
d390cad1 SS |
330 | Patrick Duval, Ted Goldstein, Vikram Koka and Glenn Engel helped develop |
331 | remote debugging. Intel Corporation, Wind River Systems, AMD, and ARM | |
332 | contributed remote debugging modules for the i960, VxWorks, A29K UDI, | |
333 | and RDI targets, respectively. | |
70b88761 | 334 | |
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335 | Brian Fox is the author of the readline libraries providing |
336 | command-line editing and command history. | |
70b88761 | 337 | |
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338 | Andrew Beers of SUNY Buffalo wrote the language-switching code, |
339 | @ifset MOD2 | |
340 | the Modula-2 support, | |
341 | @end ifset | |
342 | and contributed the Languages chapter of this manual. | |
c2bbbb22 | 343 | |
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344 | Fred Fish wrote most of the support for Unix System Vr4. |
345 | @ifclear CONLY | |
346 | He also enhanced the command-completion support to cover C++ overloaded | |
347 | symbols. | |
348 | @end ifclear | |
349 | ||
a64a6c2b | 350 | Hitachi America, Ltd. sponsored the support for Hitachi microprocessors. |
14d01801 | 351 | |
356bc67b SS |
352 | Kung Hsu, Jeff Law, and Rick Sladkey added support for hardware |
353 | watchpoints. | |
354 | ||
d390cad1 SS |
355 | Michael Snyder added support for tracepoints. |
356 | ||
356bc67b SS |
357 | Stu Grossman wrote gdbserver. |
358 | ||
359 | Jim Kingdon, Peter Schauer, Ian Taylor, and Stu Grossman made | |
360 | nearly innumerable bug fixes and cleanups throughout GDB. | |
361 | ||
d390cad1 SS |
362 | Cygnus Solutions has sponsored GDB maintenance and much of its |
363 | development since 1991. | |
364 | ||
18fae2a8 | 365 | @ifclear BARETARGET |
4eb4cf57 | 366 | @node Sample Session |
18fae2a8 | 367 | @chapter A Sample @value{GDBN} Session |
70b88761 | 368 | |
18fae2a8 | 369 | You can use this manual at your leisure to read all about @value{GDBN}. |
70b88761 | 370 | However, a handful of commands are enough to get started using the |
ed447b95 | 371 | debugger. This chapter illustrates those commands. |
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372 | |
373 | @iftex | |
6ca72cc6 | 374 | In this sample session, we emphasize user input like this: @b{input}, |
70b88761 RP |
375 | to make it easier to pick out from the surrounding output. |
376 | @end iftex | |
377 | ||
378 | @c FIXME: this example may not be appropriate for some configs, where | |
379 | @c FIXME...primary interest is in remote use. | |
18fae2a8 | 380 | |
af215b1a | 381 | One of the preliminary versions of @sc{gnu} @code{m4} (a generic macro |
70b88761 | 382 | processor) exhibits the following bug: sometimes, when we change its |
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383 | quote strings from the default, the commands used to capture one macro |
384 | definition within another stop working. In the following short @code{m4} | |
70b88761 | 385 | session, we define a macro @code{foo} which expands to @code{0000}; we |
29a2b744 | 386 | then use the @code{m4} built-in @code{defn} to define @code{bar} as the |
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387 | same thing. However, when we change the open quote string to |
388 | @code{<QUOTE>} and the close quote string to @code{<UNQUOTE>}, the same | |
389 | procedure fails to define a new synonym @code{baz}: | |
390 | ||
391 | @smallexample | |
6ca72cc6 RP |
392 | $ @b{cd gnu/m4} |
393 | $ @b{./m4} | |
394 | @b{define(foo,0000)} | |
70b88761 | 395 | |
6ca72cc6 | 396 | @b{foo} |
70b88761 | 397 | 0000 |
6ca72cc6 | 398 | @b{define(bar,defn(`foo'))} |
70b88761 | 399 | |
6ca72cc6 | 400 | @b{bar} |
70b88761 | 401 | 0000 |
6ca72cc6 | 402 | @b{changequote(<QUOTE>,<UNQUOTE>)} |
70b88761 | 403 | |
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404 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} |
405 | @b{baz} | |
406 | @b{C-d} | |
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407 | m4: End of input: 0: fatal error: EOF in string |
408 | @end smallexample | |
409 | ||
410 | @noindent | |
93918348 | 411 | Let us use @value{GDBN} to try to see what is going on. |
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412 | |
413 | @smallexample | |
18fae2a8 | 414 | $ @b{@value{GDBP} m4} |
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415 | @c FIXME: this falsifies the exact text played out, to permit smallbook |
416 | @c FIXME... format to come out better. | |
af215b1a | 417 | @value{GDBN} is free software and you are welcome to distribute copies |
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418 | of it under certain conditions; type "show copying" to see |
419 | the conditions. | |
af215b1a | 420 | There is absolutely no warranty for @value{GDBN}; type "show warranty" |
ed447b95 | 421 | for details. |
af215b1a VM |
422 | |
423 | @value{GDBN} @value{GDBVN}, Copyright 1995 Free Software Foundation, Inc... | |
18fae2a8 | 424 | (@value{GDBP}) |
70b88761 RP |
425 | @end smallexample |
426 | ||
427 | @noindent | |
9a27b06e RP |
428 | @value{GDBN} reads only enough symbol data to know where to find the |
429 | rest when needed; as a result, the first prompt comes up very quickly. | |
430 | We now tell @value{GDBN} to use a narrower display width than usual, so | |
431 | that examples fit in this manual. | |
70b88761 RP |
432 | |
433 | @smallexample | |
18fae2a8 | 434 | (@value{GDBP}) @b{set width 70} |
70b88761 RP |
435 | @end smallexample |
436 | ||
e251e767 | 437 | @noindent |
93918348 | 438 | We need to see how the @code{m4} built-in @code{changequote} works. |
70b88761 | 439 | Having looked at the source, we know the relevant subroutine is |
93918348 | 440 | @code{m4_changequote}, so we set a breakpoint there with the @value{GDBN} |
70b88761 RP |
441 | @code{break} command. |
442 | ||
443 | @smallexample | |
18fae2a8 | 444 | (@value{GDBP}) @b{break m4_changequote} |
70b88761 RP |
445 | Breakpoint 1 at 0x62f4: file builtin.c, line 879. |
446 | @end smallexample | |
447 | ||
448 | @noindent | |
18fae2a8 | 449 | Using the @code{run} command, we start @code{m4} running under @value{GDBN} |
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450 | control; as long as control does not reach the @code{m4_changequote} |
451 | subroutine, the program runs as usual: | |
452 | ||
453 | @smallexample | |
18fae2a8 | 454 | (@value{GDBP}) @b{run} |
e251e767 | 455 | Starting program: /work/Editorial/gdb/gnu/m4/m4 |
6ca72cc6 | 456 | @b{define(foo,0000)} |
70b88761 | 457 | |
6ca72cc6 | 458 | @b{foo} |
70b88761 RP |
459 | 0000 |
460 | @end smallexample | |
461 | ||
462 | @noindent | |
18fae2a8 | 463 | To trigger the breakpoint, we call @code{changequote}. @value{GDBN} |
70b88761 RP |
464 | suspends execution of @code{m4}, displaying information about the |
465 | context where it stops. | |
466 | ||
467 | @smallexample | |
6ca72cc6 | 468 | @b{changequote(<QUOTE>,<UNQUOTE>)} |
70b88761 | 469 | |
203eea5d RP |
470 | Breakpoint 1, m4_changequote (argc=3, argv=0x33c70) |
471 | at builtin.c:879 | |
38962738 | 472 | 879 if (bad_argc(TOKEN_DATA_TEXT(argv[0]),argc,1,3)) |
70b88761 RP |
473 | @end smallexample |
474 | ||
475 | @noindent | |
476 | Now we use the command @code{n} (@code{next}) to advance execution to | |
477 | the next line of the current function. | |
478 | ||
479 | @smallexample | |
18fae2a8 | 480 | (@value{GDBP}) @b{n} |
203eea5d RP |
481 | 882 set_quotes((argc >= 2) ? TOKEN_DATA_TEXT(argv[1])\ |
482 | : nil, | |
70b88761 RP |
483 | @end smallexample |
484 | ||
485 | @noindent | |
486 | @code{set_quotes} looks like a promising subroutine. We can go into it | |
487 | by using the command @code{s} (@code{step}) instead of @code{next}. | |
488 | @code{step} goes to the next line to be executed in @emph{any} | |
e251e767 | 489 | subroutine, so it steps into @code{set_quotes}. |
70b88761 RP |
490 | |
491 | @smallexample | |
18fae2a8 | 492 | (@value{GDBP}) @b{s} |
70b88761 RP |
493 | set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") |
494 | at input.c:530 | |
495 | 530 if (lquote != def_lquote) | |
496 | @end smallexample | |
497 | ||
498 | @noindent | |
29a2b744 RP |
499 | The display that shows the subroutine where @code{m4} is now |
500 | suspended (and its arguments) is called a stack frame display. It | |
501 | shows a summary of the stack. We can use the @code{backtrace} | |
502 | command (which can also be spelled @code{bt}), to see where we are | |
503 | in the stack as a whole: the @code{backtrace} command displays a | |
504 | stack frame for each active subroutine. | |
70b88761 RP |
505 | |
506 | @smallexample | |
18fae2a8 | 507 | (@value{GDBP}) @b{bt} |
70b88761 RP |
508 | #0 set_quotes (lq=0x34c78 "<QUOTE>", rq=0x34c88 "<UNQUOTE>") |
509 | at input.c:530 | |
203eea5d RP |
510 | #1 0x6344 in m4_changequote (argc=3, argv=0x33c70) |
511 | at builtin.c:882 | |
70b88761 RP |
512 | #2 0x8174 in expand_macro (sym=0x33320) at macro.c:242 |
513 | #3 0x7a88 in expand_token (obs=0x0, t=209696, td=0xf7fffa30) | |
514 | at macro.c:71 | |
515 | #4 0x79dc in expand_input () at macro.c:40 | |
516 | #5 0x2930 in main (argc=0, argv=0xf7fffb20) at m4.c:195 | |
517 | @end smallexample | |
518 | ||
519 | @noindent | |
9a27b06e | 520 | We step through a few more lines to see what happens. The first two |
70b88761 RP |
521 | times, we can use @samp{s}; the next two times we use @code{n} to avoid |
522 | falling into the @code{xstrdup} subroutine. | |
1041a570 | 523 | |
70b88761 | 524 | @smallexample |
18fae2a8 | 525 | (@value{GDBP}) @b{s} |
70b88761 | 526 | 0x3b5c 532 if (rquote != def_rquote) |
18fae2a8 | 527 | (@value{GDBP}) @b{s} |
203eea5d RP |
528 | 0x3b80 535 lquote = (lq == nil || *lq == '\0') ? \ |
529 | def_lquote : xstrdup(lq); | |
18fae2a8 | 530 | (@value{GDBP}) @b{n} |
203eea5d RP |
531 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ |
532 | : xstrdup(rq); | |
18fae2a8 | 533 | (@value{GDBP}) @b{n} |
70b88761 RP |
534 | 538 len_lquote = strlen(rquote); |
535 | @end smallexample | |
536 | ||
537 | @noindent | |
93918348 | 538 | The last line displayed looks a little odd; we can examine the variables |
70b88761 | 539 | @code{lquote} and @code{rquote} to see if they are in fact the new left |
93918348 | 540 | and right quotes we specified. We use the command @code{p} |
70b88761 RP |
541 | (@code{print}) to see their values. |
542 | ||
543 | @smallexample | |
18fae2a8 | 544 | (@value{GDBP}) @b{p lquote} |
70b88761 | 545 | $1 = 0x35d40 "<QUOTE>" |
18fae2a8 | 546 | (@value{GDBP}) @b{p rquote} |
70b88761 RP |
547 | $2 = 0x35d50 "<UNQUOTE>" |
548 | @end smallexample | |
549 | ||
550 | @noindent | |
551 | @code{lquote} and @code{rquote} are indeed the new left and right quotes. | |
93918348 RP |
552 | To look at some context, we can display ten lines of source |
553 | surrounding the current line with the @code{l} (@code{list}) command. | |
70b88761 RP |
554 | |
555 | @smallexample | |
18fae2a8 | 556 | (@value{GDBP}) @b{l} |
70b88761 | 557 | 533 xfree(rquote); |
e251e767 | 558 | 534 |
203eea5d RP |
559 | 535 lquote = (lq == nil || *lq == '\0') ? def_lquote\ |
560 | : xstrdup (lq); | |
561 | 536 rquote = (rq == nil || *rq == '\0') ? def_rquote\ | |
562 | : xstrdup (rq); | |
e251e767 | 563 | 537 |
70b88761 RP |
564 | 538 len_lquote = strlen(rquote); |
565 | 539 len_rquote = strlen(lquote); | |
566 | 540 @} | |
e251e767 | 567 | 541 |
70b88761 RP |
568 | 542 void |
569 | @end smallexample | |
570 | ||
571 | @noindent | |
93918348 | 572 | Let us step past the two lines that set @code{len_lquote} and |
70b88761 RP |
573 | @code{len_rquote}, and then examine the values of those variables. |
574 | ||
575 | @smallexample | |
18fae2a8 | 576 | (@value{GDBP}) @b{n} |
70b88761 | 577 | 539 len_rquote = strlen(lquote); |
18fae2a8 | 578 | (@value{GDBP}) @b{n} |
70b88761 | 579 | 540 @} |
18fae2a8 | 580 | (@value{GDBP}) @b{p len_lquote} |
70b88761 | 581 | $3 = 9 |
18fae2a8 | 582 | (@value{GDBP}) @b{p len_rquote} |
70b88761 RP |
583 | $4 = 7 |
584 | @end smallexample | |
585 | ||
586 | @noindent | |
587 | That certainly looks wrong, assuming @code{len_lquote} and | |
588 | @code{len_rquote} are meant to be the lengths of @code{lquote} and | |
93918348 RP |
589 | @code{rquote} respectively. We can set them to better values using |
590 | the @code{p} command, since it can print the value of | |
70b88761 | 591 | any expression---and that expression can include subroutine calls and |
e251e767 | 592 | assignments. |
70b88761 RP |
593 | |
594 | @smallexample | |
18fae2a8 | 595 | (@value{GDBP}) @b{p len_lquote=strlen(lquote)} |
70b88761 | 596 | $5 = 7 |
18fae2a8 | 597 | (@value{GDBP}) @b{p len_rquote=strlen(rquote)} |
70b88761 RP |
598 | $6 = 9 |
599 | @end smallexample | |
600 | ||
601 | @noindent | |
93918348 RP |
602 | Is that enough to fix the problem of using the new quotes with the |
603 | @code{m4} built-in @code{defn}? We can allow @code{m4} to continue | |
70b88761 RP |
604 | executing with the @code{c} (@code{continue}) command, and then try the |
605 | example that caused trouble initially: | |
606 | ||
607 | @smallexample | |
18fae2a8 | 608 | (@value{GDBP}) @b{c} |
70b88761 RP |
609 | Continuing. |
610 | ||
6ca72cc6 | 611 | @b{define(baz,defn(<QUOTE>foo<UNQUOTE>))} |
70b88761 RP |
612 | |
613 | baz | |
614 | 0000 | |
615 | @end smallexample | |
616 | ||
617 | @noindent | |
618 | Success! The new quotes now work just as well as the default ones. The | |
619 | problem seems to have been just the two typos defining the wrong | |
93918348 | 620 | lengths. We allow @code{m4} exit by giving it an EOF as input: |
70b88761 RP |
621 | |
622 | @smallexample | |
6ca72cc6 | 623 | @b{C-d} |
70b88761 RP |
624 | Program exited normally. |
625 | @end smallexample | |
626 | ||
e251e767 | 627 | @noindent |
18fae2a8 RP |
628 | The message @samp{Program exited normally.} is from @value{GDBN}; it |
629 | indicates @code{m4} has finished executing. We can end our @value{GDBN} | |
630 | session with the @value{GDBN} @code{quit} command. | |
70b88761 RP |
631 | |
632 | @smallexample | |
18fae2a8 RP |
633 | (@value{GDBP}) @b{quit} |
634 | @end smallexample | |
635 | @end ifclear | |
70b88761 | 636 | |
4eb4cf57 | 637 | @node Invocation |
18fae2a8 | 638 | @chapter Getting In and Out of @value{GDBN} |
70b88761 | 639 | |
18fae2a8 | 640 | This chapter discusses how to start @value{GDBN}, and how to get out of it. |
af215b1a VM |
641 | The essentials are: |
642 | @itemize @bullet | |
643 | @item | |
644 | type @samp{@value{GDBP}} to start GDB. | |
645 | @item | |
646 | type @kbd{quit} or @kbd{C-d} to exit. | |
647 | @end itemize | |
29a2b744 | 648 | |
70b88761 | 649 | @menu |
ed447b95 RP |
650 | * Invoking GDB:: How to start @value{GDBN} |
651 | * Quitting GDB:: How to quit @value{GDBN} | |
ed447b95 | 652 | * Shell Commands:: How to use shell commands inside @value{GDBN} |
70b88761 | 653 | @end menu |
18fae2a8 RP |
654 | |
655 | @node Invoking GDB | |
ed447b95 | 656 | @section Invoking @value{GDBN} |
18fae2a8 | 657 | |
a64a6c2b | 658 | @ifset H8EXCLUSIVE |
18fae2a8 | 659 | For details on starting up @value{GDBP} as a |
a64a6c2b RP |
660 | remote debugger attached to a Hitachi microprocessor, see @ref{Hitachi |
661 | Remote,,@value{GDBN} and Hitachi Microprocessors}. | |
18fae2a8 | 662 | @end ifset |
4eb4cf57 | 663 | |
ed447b95 | 664 | Invoke @value{GDBN} by running the program @code{@value{GDBP}}. Once started, |
18fae2a8 | 665 | @value{GDBN} reads commands from the terminal until you tell it to exit. |
70b88761 | 666 | |
18fae2a8 | 667 | You can also run @code{@value{GDBP}} with a variety of arguments and options, |
c7cb8acb RP |
668 | to specify more of your debugging environment at the outset. |
669 | ||
18fae2a8 | 670 | @ifset GENERIC |
c7cb8acb RP |
671 | The command-line options described here are designed |
672 | to cover a variety of situations; in some environments, some of these | |
673 | options may effectively be unavailable. | |
18fae2a8 | 674 | @end ifset |
c7cb8acb | 675 | |
18fae2a8 | 676 | The most usual way to start @value{GDBN} is with one argument, |
4eb4cf57 | 677 | specifying an executable program: |
1041a570 | 678 | |
70b88761 | 679 | @example |
18fae2a8 | 680 | @value{GDBP} @var{program} |
70b88761 | 681 | @end example |
1041a570 | 682 | |
18fae2a8 | 683 | @ifclear BARETARGET |
70b88761 | 684 | @noindent |
29a2b744 RP |
685 | You can also start with both an executable program and a core file |
686 | specified: | |
1041a570 | 687 | |
70b88761 | 688 | @example |
18fae2a8 | 689 | @value{GDBP} @var{program} @var{core} |
70b88761 RP |
690 | @end example |
691 | ||
b80282d5 RP |
692 | You can, instead, specify a process ID as a second argument, if you want |
693 | to debug a running process: | |
1041a570 | 694 | |
b80282d5 | 695 | @example |
18fae2a8 | 696 | @value{GDBP} @var{program} 1234 |
b80282d5 | 697 | @end example |
1041a570 | 698 | |
b80282d5 | 699 | @noindent |
18fae2a8 RP |
700 | would attach @value{GDBN} to process @code{1234} (unless you also have a file |
701 | named @file{1234}; @value{GDBN} does check for a core file first). | |
b80282d5 | 702 | |
c7cb8acb | 703 | Taking advantage of the second command-line argument requires a fairly |
18fae2a8 | 704 | complete operating system; when you use @value{GDBN} as a remote debugger |
c7cb8acb RP |
705 | attached to a bare board, there may not be any notion of ``process'', |
706 | and there is often no way to get a core dump. | |
18fae2a8 | 707 | @end ifclear |
c7cb8acb | 708 | |
af215b1a VM |
709 | You can run @code{gdb} without printing the front material, which describes |
710 | @value{GDBN}'s non-warranty, by specifying @code{-silent}: | |
711 | ||
712 | @smallexample | |
713 | @value{GDBP} @var{-silent} | |
714 | @end smallexample | |
715 | ||
70b88761 | 716 | @noindent |
18fae2a8 RP |
717 | You can further control how @value{GDBN} starts up by using command-line |
718 | options. @value{GDBN} itself can remind you of the options available. | |
29a2b744 RP |
719 | |
720 | @noindent | |
721 | Type | |
722 | ||
70b88761 | 723 | @example |
18fae2a8 | 724 | @value{GDBP} -help |
70b88761 | 725 | @end example |
29a2b744 | 726 | |
70b88761 | 727 | @noindent |
29a2b744 | 728 | to display all available options and briefly describe their use |
18fae2a8 | 729 | (@samp{@value{GDBP} -h} is a shorter equivalent). |
70b88761 RP |
730 | |
731 | All options and command line arguments you give are processed | |
732 | in sequential order. The order makes a difference when the | |
e251e767 | 733 | @samp{-x} option is used. |
70b88761 | 734 | |
18fae2a8 | 735 | |
70b88761 | 736 | @menu |
18fae2a8 RP |
737 | @ifclear GENERIC |
738 | @ifset REMOTESTUB | |
739 | * Remote Serial:: @value{GDBN} remote serial protocol | |
740 | @end ifset | |
a64a6c2b | 741 | @ifset I960 |
18fae2a8 RP |
742 | * i960-Nindy Remote:: @value{GDBN} with a remote i960 (Nindy) |
743 | @end ifset | |
a64a6c2b | 744 | @ifset AMD29K |
b1955f0b RP |
745 | * UDI29K Remote:: The UDI protocol for AMD29K |
746 | * EB29K Remote:: The EBMON protocol for AMD29K | |
18fae2a8 RP |
747 | @end ifset |
748 | @ifset VXWORKS | |
749 | * VxWorks Remote:: @value{GDBN} and VxWorks | |
750 | @end ifset | |
a64a6c2b | 751 | @ifset ST2000 |
18fae2a8 RP |
752 | * ST2000 Remote:: @value{GDBN} with a Tandem ST2000 |
753 | @end ifset | |
a64a6c2b RP |
754 | @ifset H8 |
755 | * Hitachi Remote:: @value{GDBN} and Hitachi Microprocessors | |
18fae2a8 | 756 | @end ifset |
34ae25cd RP |
757 | @ifset MIPS |
758 | * MIPS Remote:: @value{GDBN} and MIPS boards | |
759 | @end ifset | |
146ff252 DE |
760 | @ifset SPARCLET |
761 | * Sparclet Remote:: @value{GDBN} and Sparclet boards | |
762 | @end ifset | |
fe715d06 RP |
763 | @ifset SIMS |
764 | * Simulator:: Simulated CPU target | |
18fae2a8 RP |
765 | @end ifset |
766 | @end ifclear | |
1d7c3357 | 767 | @c remnant makeinfo bug requires this blank line after *two* end-ifblahs: |
18fae2a8 | 768 | |
ed447b95 RP |
769 | * File Options:: Choosing files |
770 | * Mode Options:: Choosing modes | |
18fae2a8 | 771 | @end menu |
18fae2a8 RP |
772 | |
773 | @ifclear GENERIC | |
4af6d502 | 774 | @include remote.texi |
18fae2a8 | 775 | @end ifclear |
4eb4cf57 RP |
776 | |
777 | @node File Options | |
93928b60 | 778 | @subsection Choosing files |
70b88761 | 779 | |
18fae2a8 RP |
780 | @ifclear BARETARGET |
781 | When @value{GDBN} starts, it reads any arguments other than options as | |
29a2b744 RP |
782 | specifying an executable file and core file (or process ID). This is |
783 | the same as if the arguments were specified by the @samp{-se} and | |
18fae2a8 | 784 | @samp{-c} options respectively. (@value{GDBN} reads the first argument |
29a2b744 RP |
785 | that does not have an associated option flag as equivalent to the |
786 | @samp{-se} option followed by that argument; and the second argument | |
787 | that does not have an associated option flag, if any, as equivalent to | |
788 | the @samp{-c} option followed by that argument.) | |
18fae2a8 RP |
789 | @end ifclear |
790 | @ifset BARETARGET | |
791 | When @value{GDBN} starts, it reads any argument other than options as | |
4eb4cf57 RP |
792 | specifying an executable file. This is the same as if the argument was |
793 | specified by the @samp{-se} option. | |
18fae2a8 | 794 | @end ifset |
29a2b744 RP |
795 | |
796 | Many options have both long and short forms; both are shown in the | |
18fae2a8 | 797 | following list. @value{GDBN} also recognizes the long forms if you truncate |
29a2b744 RP |
798 | them, so long as enough of the option is present to be unambiguous. |
799 | (If you prefer, you can flag option arguments with @samp{--} rather | |
800 | than @samp{-}, though we illustrate the more usual convention.) | |
70b88761 RP |
801 | |
802 | @table @code | |
6b51acad | 803 | @item -symbols @var{file} |
70b88761 RP |
804 | @itemx -s @var{file} |
805 | Read symbol table from file @var{file}. | |
806 | ||
6b51acad | 807 | @item -exec @var{file} |
70b88761 RP |
808 | @itemx -e @var{file} |
809 | Use file @var{file} as the executable file to execute when | |
1d7c3357 RP |
810 | @ifset BARETARGET |
811 | appropriate. | |
812 | @end ifset | |
813 | @ifclear BARETARGET | |
70b88761 RP |
814 | appropriate, and for examining pure data in conjunction with a core |
815 | dump. | |
1d7c3357 | 816 | @end ifclear |
70b88761 | 817 | |
6b51acad | 818 | @item -se @var{file} |
70b88761 RP |
819 | Read symbol table from file @var{file} and use it as the executable |
820 | file. | |
821 | ||
18fae2a8 | 822 | @ifclear BARETARGET |
6b51acad | 823 | @item -core @var{file} |
70b88761 RP |
824 | @itemx -c @var{file} |
825 | Use file @var{file} as a core dump to examine. | |
d55320a0 RP |
826 | |
827 | @item -c @var{number} | |
828 | Connect to process ID @var{number}, as with the @code{attach} command | |
829 | (unless there is a file in core-dump format named @var{number}, in which | |
830 | case @samp{-c} specifies that file as a core dump to read). | |
18fae2a8 | 831 | @end ifclear |
70b88761 | 832 | |
6b51acad | 833 | @item -command @var{file} |
70b88761 | 834 | @itemx -x @var{file} |
93928b60 RP |
835 | Execute @value{GDBN} commands from file @var{file}. @xref{Command |
836 | Files,, Command files}. | |
70b88761 | 837 | |
6b51acad | 838 | @item -directory @var{directory} |
70b88761 RP |
839 | @itemx -d @var{directory} |
840 | Add @var{directory} to the path to search for source files. | |
14d01801 | 841 | |
18fae2a8 | 842 | @ifclear BARETARGET |
14d01801 RP |
843 | @item -m |
844 | @itemx -mapped | |
845 | @emph{Warning: this option depends on operating system facilities that are not | |
846 | supported on all systems.}@* | |
77b46d13 JG |
847 | If memory-mapped files are available on your system through the @code{mmap} |
848 | system call, you can use this option | |
18fae2a8 | 849 | to have @value{GDBN} write the symbols from your |
77b46d13 | 850 | program into a reusable file in the current directory. If the program you are debugging is |
9a27b06e RP |
851 | called @file{/tmp/fred}, the mapped symbol file is @file{./fred.syms}. |
852 | Future @value{GDBN} debugging sessions notice the presence of this file, | |
853 | and can quickly map in symbol information from it, rather than reading | |
77b46d13 JG |
854 | the symbol table from the executable program. |
855 | ||
1d7c3357 RP |
856 | The @file{.syms} file is specific to the host machine where @value{GDBN} |
857 | is run. It holds an exact image of the internal @value{GDBN} symbol | |
858 | table. It cannot be shared across multiple host platforms. | |
18fae2a8 | 859 | @end ifclear |
77b46d13 JG |
860 | |
861 | @item -r | |
862 | @itemx -readnow | |
863 | Read each symbol file's entire symbol table immediately, rather than | |
864 | the default, which is to read it incrementally as it is needed. | |
865 | This makes startup slower, but makes future operations faster. | |
70b88761 RP |
866 | @end table |
867 | ||
18fae2a8 | 868 | @ifclear BARETARGET |
93918348 RP |
869 | The @code{-mapped} and @code{-readnow} options are typically combined in |
870 | order to build a @file{.syms} file that contains complete symbol | |
93928b60 | 871 | information. (@xref{Files,,Commands to specify files}, for information |
af215b1a | 872 | |
93918348 | 873 | a @file{.syms} file for future use is: |
77b46d13 JG |
874 | |
875 | @example | |
876 | gdb -batch -nx -mapped -readnow programname | |
877 | @end example | |
18fae2a8 | 878 | @end ifclear |
77b46d13 | 879 | |
4eb4cf57 | 880 | @node Mode Options |
93928b60 | 881 | @subsection Choosing modes |
1041a570 | 882 | |
18fae2a8 | 883 | You can run @value{GDBN} in various alternative modes---for example, in |
29a2b744 | 884 | batch mode or quiet mode. |
70b88761 RP |
885 | |
886 | @table @code | |
887 | @item -nx | |
888 | @itemx -n | |
d55320a0 RP |
889 | Do not execute commands from any initialization files (normally called |
890 | @file{@value{GDBINIT}}). Normally, the commands in these files are | |
891 | executed after all the command options and arguments have been | |
892 | processed. @xref{Command Files,,Command files}. | |
70b88761 RP |
893 | |
894 | @item -quiet | |
895 | @itemx -q | |
896 | ``Quiet''. Do not print the introductory and copyright messages. These | |
c338a2fd | 897 | messages are also suppressed in batch mode. |
70b88761 RP |
898 | |
899 | @item -batch | |
d55320a0 RP |
900 | Run in batch mode. Exit with status @code{0} after processing all the |
901 | command files specified with @samp{-x} (and all commands from | |
902 | initialization files, if not inhibited with @samp{-n}). Exit with | |
903 | nonzero status if an error occurs in executing the @value{GDBN} commands | |
904 | in the command files. | |
70b88761 | 905 | |
18fae2a8 | 906 | Batch mode may be useful for running @value{GDBN} as a filter, for example to |
70b88761 | 907 | download and run a program on another computer; in order to make this |
e251e767 | 908 | more useful, the message |
1041a570 | 909 | |
70b88761 RP |
910 | @example |
911 | Program exited normally. | |
912 | @end example | |
1041a570 | 913 | |
70b88761 | 914 | @noindent |
18fae2a8 | 915 | (which is ordinarily issued whenever a program running under @value{GDBN} control |
70b88761 RP |
916 | terminates) is not issued when running in batch mode. |
917 | ||
6b51acad | 918 | @item -cd @var{directory} |
18fae2a8 | 919 | Run @value{GDBN} using @var{directory} as its working directory, |
70b88761 RP |
920 | instead of the current directory. |
921 | ||
18fae2a8 | 922 | @ifset LUCID |
45c53080 | 923 | @item -context @var{authentication} |
18fae2a8 | 924 | When the Energize programming system starts up @value{GDBN}, it uses this |
6ca72cc6 | 925 | option to trigger an alternate mode of interaction. |
18fae2a8 | 926 | @var{authentication} is a pair of numeric codes that identify @value{GDBN} |
6ca72cc6 | 927 | as a client in the Energize environment. Avoid this option when you run |
18fae2a8 RP |
928 | @value{GDBN} directly from the command line. See @ref{Energize,,Using |
929 | @value{GDBN} with Energize} for more discussion of using @value{GDBN} with Energize. | |
930 | @end ifset | |
6ca72cc6 | 931 | |
1d7c3357 | 932 | @ifclear DOSHOST |
70b88761 RP |
933 | @item -fullname |
934 | @itemx -f | |
af215b1a | 935 | @sc{gnu} Emacs sets this option when it runs @value{GDBN} as a subprocess. It tells @value{GDBN} |
70b88761 RP |
936 | to output the full file name and line number in a standard, |
937 | recognizable fashion each time a stack frame is displayed (which | |
29a2b744 | 938 | includes each time your program stops). This recognizable format looks |
70b88761 RP |
939 | like two @samp{\032} characters, followed by the file name, line number |
940 | and character position separated by colons, and a newline. The | |
18fae2a8 | 941 | Emacs-to-@value{GDBN} interface program uses the two @samp{\032} characters as |
70b88761 | 942 | a signal to display the source code for the frame. |
1d7c3357 | 943 | @end ifclear |
70b88761 | 944 | |
18fae2a8 | 945 | @ifset SERIAL |
70b88761 RP |
946 | @item -b @var{bps} |
947 | Set the line speed (baud rate or bits per second) of any serial | |
18fae2a8 | 948 | interface used by @value{GDBN} for remote debugging. |
70b88761 | 949 | |
6b51acad | 950 | @item -tty @var{device} |
70b88761 | 951 | Run using @var{device} for your program's standard input and output. |
29a2b744 | 952 | @c FIXME: kingdon thinks there is more to -tty. Investigate. |
18fae2a8 | 953 | @end ifset |
70b88761 RP |
954 | @end table |
955 | ||
ed447b95 RP |
956 | @node Quitting GDB |
957 | @section Quitting @value{GDBN} | |
18fae2a8 | 958 | @cindex exiting @value{GDBN} |
ed447b95 | 959 | @cindex leaving @value{GDBN} |
1041a570 | 960 | |
70b88761 | 961 | @table @code |
f94cadf9 | 962 | @kindex quit @r{[}@var{expression}@r{]} |
70b88761 | 963 | @kindex q |
af215b1a VM |
964 | @item quit |
965 | To exit @value{GDBN}, use the @code{quit} command (abbreviated @code{q}), or | |
f94cadf9 SS |
966 | type an end-of-file character (usually @kbd{C-d}). If you do not supply |
967 | @var{expression}, @value{GDBN} will terminate normally; otherwise it will | |
968 | terminate using the result of @var{expression} as the error code. | |
70b88761 RP |
969 | @end table |
970 | ||
971 | @cindex interrupt | |
9a27b06e RP |
972 | An interrupt (often @kbd{C-c}) does not exit from @value{GDBN}, but rather |
973 | terminates the action of any @value{GDBN} command that is in progress and | |
974 | returns to @value{GDBN} command level. It is safe to type the interrupt | |
18fae2a8 | 975 | character at any time because @value{GDBN} does not allow it to take effect |
70b88761 RP |
976 | until a time when it is safe. |
977 | ||
18fae2a8 | 978 | @ifclear BARETARGET |
ed447b95 RP |
979 | If you have been using @value{GDBN} to control an attached process or |
980 | device, you can release it with the @code{detach} command | |
93928b60 | 981 | (@pxref{Attach, ,Debugging an already-running process}). |
18fae2a8 | 982 | @end ifclear |
70b88761 | 983 | |
4eb4cf57 | 984 | @node Shell Commands |
93928b60 | 985 | @section Shell commands |
1041a570 | 986 | |
70b88761 | 987 | If you need to execute occasional shell commands during your |
18fae2a8 | 988 | debugging session, there is no need to leave or suspend @value{GDBN}; you can |
70b88761 RP |
989 | just use the @code{shell} command. |
990 | ||
991 | @table @code | |
70b88761 RP |
992 | @kindex shell |
993 | @cindex shell escape | |
af215b1a | 994 | @item shell @var{command string} |
75f844cc | 995 | Invoke a the standard shell to execute @var{command string}. |
a1eff6c2 | 996 | @ifclear DOSHOST |
75f844cc RP |
997 | If it exists, the environment variable @code{SHELL} determines which |
998 | shell to run. Otherwise @value{GDBN} uses @code{/bin/sh}. | |
a1eff6c2 | 999 | @end ifclear |
70b88761 RP |
1000 | @end table |
1001 | ||
1002 | The utility @code{make} is often needed in development environments. | |
a1eff6c2 RP |
1003 | You do not have to use the @code{shell} command for this purpose in |
1004 | @value{GDBN}: | |
70b88761 RP |
1005 | |
1006 | @table @code | |
70b88761 RP |
1007 | @kindex make |
1008 | @cindex calling make | |
af215b1a | 1009 | @item make @var{make-args} |
a1eff6c2 | 1010 | Execute the @code{make} program with the specified |
70b88761 RP |
1011 | arguments. This is equivalent to @samp{shell make @var{make-args}}. |
1012 | @end table | |
1013 | ||
4eb4cf57 | 1014 | @node Commands |
18fae2a8 | 1015 | @chapter @value{GDBN} Commands |
70b88761 | 1016 | |
18fae2a8 | 1017 | You can abbreviate a @value{GDBN} command to the first few letters of the command |
6f3ec223 | 1018 | name, if that abbreviation is unambiguous; and you can repeat certain |
18fae2a8 RP |
1019 | @value{GDBN} commands by typing just @key{RET}. You can also use the @key{TAB} |
1020 | key to get @value{GDBN} to fill out the rest of a word in a command (or to | |
93918348 | 1021 | show you the alternatives available, if there is more than one possibility). |
29a2b744 | 1022 | |
70b88761 | 1023 | @menu |
ed447b95 RP |
1024 | * Command Syntax:: How to give commands to @value{GDBN} |
1025 | * Completion:: Command completion | |
1026 | * Help:: How to ask @value{GDBN} for help | |
70b88761 RP |
1027 | @end menu |
1028 | ||
4eb4cf57 | 1029 | @node Command Syntax |
93928b60 | 1030 | @section Command syntax |
1041a570 | 1031 | |
fe715d06 RP |
1032 | A @value{GDBN} command is a single line of input. There is no limit on |
1033 | how long it can be. It starts with a command name, which is followed by | |
1034 | arguments whose meaning depends on the command name. For example, the | |
1035 | command @code{step} accepts an argument which is the number of times to | |
1036 | step, as in @samp{step 5}. You can also use the @code{step} command | |
1037 | with no arguments. Some command names do not allow any arguments. | |
70b88761 RP |
1038 | |
1039 | @cindex abbreviation | |
18fae2a8 | 1040 | @value{GDBN} command names may always be truncated if that abbreviation is |
70b88761 RP |
1041 | unambiguous. Other possible command abbreviations are listed in the |
1042 | documentation for individual commands. In some cases, even ambiguous | |
1043 | abbreviations are allowed; for example, @code{s} is specially defined as | |
1044 | equivalent to @code{step} even though there are other commands whose | |
1045 | names start with @code{s}. You can test abbreviations by using them as | |
7463aadd | 1046 | arguments to the @code{help} command. |
70b88761 | 1047 | |
e251e767 | 1048 | @cindex repeating commands |
70b88761 | 1049 | @kindex RET |
18fae2a8 | 1050 | A blank line as input to @value{GDBN} (typing just @key{RET}) means to |
70b88761 | 1051 | repeat the previous command. Certain commands (for example, @code{run}) |
9a27b06e | 1052 | will not repeat this way; these are commands whose unintentional |
70b88761 RP |
1053 | repetition might cause trouble and which you are unlikely to want to |
1054 | repeat. | |
1055 | ||
1056 | The @code{list} and @code{x} commands, when you repeat them with | |
1057 | @key{RET}, construct new arguments rather than repeating | |
1058 | exactly as typed. This permits easy scanning of source or memory. | |
1059 | ||
18fae2a8 | 1060 | @value{GDBN} can also use @key{RET} in another way: to partition lengthy |
b80282d5 | 1061 | output, in a way similar to the common utility @code{more} |
93928b60 RP |
1062 | (@pxref{Screen Size,,Screen size}). Since it is easy to press one |
1063 | @key{RET} too many in this situation, @value{GDBN} disables command | |
1064 | repetition after any command that generates this sort of display. | |
b80282d5 | 1065 | |
70b88761 RP |
1066 | @kindex # |
1067 | @cindex comment | |
fe715d06 RP |
1068 | Any text from a @kbd{#} to the end of the line is a comment; it does |
1069 | nothing. This is useful mainly in command files (@pxref{Command | |
1070 | Files,,Command files}). | |
70b88761 | 1071 | |
4eb4cf57 | 1072 | @node Completion |
93928b60 | 1073 | @section Command completion |
6f3ec223 RP |
1074 | |
1075 | @cindex completion | |
1076 | @cindex word completion | |
93918348 | 1077 | @value{GDBN} can fill in the rest of a word in a command for you, if there is |
6f3ec223 | 1078 | only one possibility; it can also show you what the valid possibilities |
18fae2a8 RP |
1079 | are for the next word in a command, at any time. This works for @value{GDBN} |
1080 | commands, @value{GDBN} subcommands, and the names of symbols in your program. | |
6f3ec223 | 1081 | |
18fae2a8 | 1082 | Press the @key{TAB} key whenever you want @value{GDBN} to fill out the rest |
9a27b06e RP |
1083 | of a word. If there is only one possibility, @value{GDBN} fills in the |
1084 | word, and waits for you to finish the command (or press @key{RET} to | |
6f3ec223 RP |
1085 | enter it). For example, if you type |
1086 | ||
93918348 | 1087 | @c FIXME "@key" does not distinguish its argument sufficiently to permit |
0fdc6e27 RP |
1088 | @c complete accuracy in these examples; space introduced for clarity. |
1089 | @c If texinfo enhancements make it unnecessary, it would be nice to | |
1090 | @c replace " @key" by "@key" in the following... | |
6f3ec223 | 1091 | @example |
18fae2a8 | 1092 | (@value{GDBP}) info bre @key{TAB} |
6f3ec223 RP |
1093 | @end example |
1094 | ||
1095 | @noindent | |
93918348 | 1096 | @value{GDBN} fills in the rest of the word @samp{breakpoints}, since that is |
6f3ec223 RP |
1097 | the only @code{info} subcommand beginning with @samp{bre}: |
1098 | ||
1099 | @example | |
18fae2a8 | 1100 | (@value{GDBP}) info breakpoints |
6f3ec223 RP |
1101 | @end example |
1102 | ||
1103 | @noindent | |
1104 | You can either press @key{RET} at this point, to run the @code{info | |
1105 | breakpoints} command, or backspace and enter something else, if | |
93918348 | 1106 | @samp{breakpoints} does not look like the command you expected. (If you |
6f3ec223 RP |
1107 | were sure you wanted @code{info breakpoints} in the first place, you |
1108 | might as well just type @key{RET} immediately after @samp{info bre}, | |
1109 | to exploit command abbreviations rather than command completion). | |
1110 | ||
1111 | If there is more than one possibility for the next word when you press | |
9a27b06e RP |
1112 | @key{TAB}, @value{GDBN} sounds a bell. You can either supply more |
1113 | characters and try again, or just press @key{TAB} a second time; | |
1114 | @value{GDBN} displays all the possible completions for that word. For | |
6f3ec223 | 1115 | example, you might want to set a breakpoint on a subroutine whose name |
18fae2a8 | 1116 | begins with @samp{make_}, but when you type @kbd{b make_@key{TAB}} @value{GDBN} |
9a27b06e | 1117 | just sounds the bell. Typing @key{TAB} again displays all the |
6f3ec223 RP |
1118 | function names in your program that begin with those characters, for |
1119 | example: | |
1120 | ||
1121 | @example | |
18fae2a8 RP |
1122 | (@value{GDBP}) b make_ @key{TAB} |
1123 | @exdent @value{GDBN} sounds bell; press @key{TAB} again, to see: | |
6f3ec223 RP |
1124 | make_a_section_from_file make_environ |
1125 | make_abs_section make_function_type | |
1126 | make_blockvector make_pointer_type | |
1127 | make_cleanup make_reference_type | |
1128 | make_command make_symbol_completion_list | |
18fae2a8 | 1129 | (@value{GDBP}) b make_ |
6f3ec223 RP |
1130 | @end example |
1131 | ||
1132 | @noindent | |
18fae2a8 | 1133 | After displaying the available possibilities, @value{GDBN} copies your |
b1385986 | 1134 | partial input (@samp{b make_} in the example) so you can finish the |
6f3ec223 RP |
1135 | command. |
1136 | ||
1137 | If you just want to see the list of alternatives in the first place, you | |
b1385986 | 1138 | can press @kbd{M-?} rather than pressing @key{TAB} twice. @kbd{M-?} |
0f153e74 | 1139 | means @kbd{@key{META} ?}. You can type this |
18fae2a8 | 1140 | @ifclear DOSHOST |
0f153e74 | 1141 | either by holding down a |
b1385986 | 1142 | key designated as the @key{META} shift on your keyboard (if there is |
0f153e74 | 1143 | one) while typing @kbd{?}, or |
18fae2a8 | 1144 | @end ifclear |
0f153e74 | 1145 | as @key{ESC} followed by @kbd{?}. |
6f3ec223 RP |
1146 | |
1147 | @cindex quotes in commands | |
1148 | @cindex completion of quoted strings | |
1149 | Sometimes the string you need, while logically a ``word'', may contain | |
18fae2a8 | 1150 | parentheses or other characters that @value{GDBN} normally excludes from its |
6f3ec223 | 1151 | notion of a word. To permit word completion to work in this situation, |
18fae2a8 | 1152 | you may enclose words in @code{'} (single quote marks) in @value{GDBN} commands. |
6f3ec223 | 1153 | |
1d7c3357 | 1154 | @ifclear CONLY |
6f3ec223 RP |
1155 | The most likely situation where you might need this is in typing the |
1156 | name of a C++ function. This is because C++ allows function overloading | |
1157 | (multiple definitions of the same function, distinguished by argument | |
b1385986 RP |
1158 | type). For example, when you want to set a breakpoint you may need to |
1159 | distinguish whether you mean the version of @code{name} that takes an | |
1160 | @code{int} parameter, @code{name(int)}, or the version that takes a | |
1161 | @code{float} parameter, @code{name(float)}. To use the word-completion | |
1162 | facilities in this situation, type a single quote @code{'} at the | |
18fae2a8 | 1163 | beginning of the function name. This alerts @value{GDBN} that it may need to |
b1385986 RP |
1164 | consider more information than usual when you press @key{TAB} or |
1165 | @kbd{M-?} to request word completion: | |
6f3ec223 RP |
1166 | |
1167 | @example | |
18fae2a8 | 1168 | (@value{GDBP}) b 'bubble( @key{M-?} |
0fdc6e27 | 1169 | bubble(double,double) bubble(int,int) |
18fae2a8 | 1170 | (@value{GDBP}) b 'bubble( |
6f3ec223 RP |
1171 | @end example |
1172 | ||
9a27b06e RP |
1173 | In some cases, @value{GDBN} can tell that completing a name requires using |
1174 | quotes. When this happens, @value{GDBN} inserts the quote for you (while | |
0fdc6e27 RP |
1175 | completing as much as it can) if you do not type the quote in the first |
1176 | place: | |
1177 | ||
1178 | @example | |
18fae2a8 RP |
1179 | (@value{GDBP}) b bub @key{TAB} |
1180 | @exdent @value{GDBN} alters your input line to the following, and rings a bell: | |
1181 | (@value{GDBP}) b 'bubble( | |
0fdc6e27 RP |
1182 | @end example |
1183 | ||
1184 | @noindent | |
18fae2a8 | 1185 | In general, @value{GDBN} can tell that a quote is needed (and inserts it) if |
0fdc6e27 RP |
1186 | you have not yet started typing the argument list when you ask for |
1187 | completion on an overloaded symbol. | |
1d7c3357 | 1188 | @end ifclear |
0fdc6e27 RP |
1189 | |
1190 | ||
4eb4cf57 | 1191 | @node Help |
93928b60 | 1192 | @section Getting help |
70b88761 RP |
1193 | @cindex online documentation |
1194 | @kindex help | |
1041a570 | 1195 | |
af215b1a VM |
1196 | You can always ask @value{GDBN} itself for information on its commands, |
1197 | using the command @code{help}. | |
70b88761 RP |
1198 | |
1199 | @table @code | |
af215b1a | 1200 | @kindex h |
70b88761 RP |
1201 | @item help |
1202 | @itemx h | |
70b88761 RP |
1203 | You can use @code{help} (abbreviated @code{h}) with no arguments to |
1204 | display a short list of named classes of commands: | |
1041a570 | 1205 | |
70b88761 | 1206 | @smallexample |
18fae2a8 | 1207 | (@value{GDBP}) help |
70b88761 RP |
1208 | List of classes of commands: |
1209 | ||
1210 | running -- Running the program | |
1211 | stack -- Examining the stack | |
1212 | data -- Examining data | |
1213 | breakpoints -- Making program stop at certain points | |
1214 | files -- Specifying and examining files | |
1215 | status -- Status inquiries | |
1216 | support -- Support facilities | |
1217 | user-defined -- User-defined commands | |
1218 | aliases -- Aliases of other commands | |
1219 | obscure -- Obscure features | |
1220 | ||
203eea5d RP |
1221 | Type "help" followed by a class name for a list of |
1222 | commands in that class. | |
1223 | Type "help" followed by command name for full | |
1224 | documentation. | |
70b88761 | 1225 | Command name abbreviations are allowed if unambiguous. |
18fae2a8 | 1226 | (@value{GDBP}) |
70b88761 RP |
1227 | @end smallexample |
1228 | ||
1229 | @item help @var{class} | |
1230 | Using one of the general help classes as an argument, you can get a | |
1231 | list of the individual commands in that class. For example, here is the | |
1232 | help display for the class @code{status}: | |
1041a570 | 1233 | |
70b88761 | 1234 | @smallexample |
18fae2a8 | 1235 | (@value{GDBP}) help status |
70b88761 RP |
1236 | Status inquiries. |
1237 | ||
1238 | List of commands: | |
1239 | ||
8c69096b RP |
1240 | @c Line break in "show" line falsifies real output, but needed |
1241 | @c to fit in smallbook page size. | |
1242 | show -- Generic command for showing things set | |
1243 | with "set" | |
70b88761 RP |
1244 | info -- Generic command for printing status |
1245 | ||
203eea5d RP |
1246 | Type "help" followed by command name for full |
1247 | documentation. | |
70b88761 | 1248 | Command name abbreviations are allowed if unambiguous. |
18fae2a8 | 1249 | (@value{GDBP}) |
70b88761 RP |
1250 | @end smallexample |
1251 | ||
1252 | @item help @var{command} | |
9a27b06e | 1253 | With a command name as @code{help} argument, @value{GDBN} displays a |
e251e767 | 1254 | short paragraph on how to use that command. |
af215b1a VM |
1255 | |
1256 | @kindex complete | |
1257 | @item complete @var{args} | |
1258 | The @code{complete @var{args}} command lists all the possible completions | |
1259 | for the beginning of a command. Use @var{args} to specify the beginning of the | |
1260 | command you want completed. For example: | |
1261 | ||
1262 | @smallexample | |
1263 | complete i | |
1264 | @end smallexample | |
1265 | ||
1266 | @noindent results in: | |
1267 | ||
1268 | @smallexample | |
1269 | info | |
1270 | inspect | |
1271 | ignore | |
1272 | @end smallexample | |
1273 | ||
1274 | @noindent This is intended for use by @sc{gnu} Emacs. | |
70b88761 RP |
1275 | @end table |
1276 | ||
18fae2a8 | 1277 | In addition to @code{help}, you can use the @value{GDBN} commands @code{info} |
70b88761 | 1278 | and @code{show} to inquire about the state of your program, or the state |
18fae2a8 | 1279 | of @value{GDBN} itself. Each command supports many topics of inquiry; this |
70b88761 RP |
1280 | manual introduces each of them in the appropriate context. The listings |
1281 | under @code{info} and under @code{show} in the Index point to | |
29a2b744 | 1282 | all the sub-commands. @xref{Index}. |
70b88761 RP |
1283 | |
1284 | @c @group | |
1285 | @table @code | |
70b88761 RP |
1286 | @kindex info |
1287 | @kindex i | |
af215b1a | 1288 | @item info |
70b88761 | 1289 | This command (abbreviated @code{i}) is for describing the state of your |
ed447b95 RP |
1290 | program. For example, you can list the arguments given to your program |
1291 | with @code{info args}, list the registers currently in use with @code{info | |
1292 | registers}, or list the breakpoints you have set with @code{info breakpoints}. | |
70b88761 RP |
1293 | You can get a complete list of the @code{info} sub-commands with |
1294 | @w{@code{help info}}. | |
1295 | ||
af215b1a VM |
1296 | @kindex set |
1297 | @item set | |
1298 | You can assign the result of an expresson to an environment variable with | |
1299 | @code{set}. For example, you can set the @value{GDBN} prompt to a $-sign with | |
1300 | @code{set prompt $}. | |
1301 | ||
70b88761 RP |
1302 | @kindex show |
1303 | @item show | |
af215b1a VM |
1304 | In contrast to @code{info}, @code{show} is for describing the state of |
1305 | @value{GDBN} itself. | |
70b88761 RP |
1306 | You can change most of the things you can @code{show}, by using the |
1307 | related command @code{set}; for example, you can control what number | |
1308 | system is used for displays with @code{set radix}, or simply inquire | |
e251e767 | 1309 | which is currently in use with @code{show radix}. |
70b88761 RP |
1310 | |
1311 | @kindex info set | |
1312 | To display all the settable parameters and their current | |
1313 | values, you can use @code{show} with no arguments; you may also use | |
1314 | @code{info set}. Both commands produce the same display. | |
1315 | @c FIXME: "info set" violates the rule that "info" is for state of | |
1316 | @c FIXME...program. Ck w/ GNU: "info set" to be called something else, | |
1317 | @c FIXME...or change desc of rule---eg "state of prog and debugging session"? | |
1318 | @end table | |
1319 | @c @end group | |
1320 | ||
1321 | Here are three miscellaneous @code{show} subcommands, all of which are | |
1322 | exceptional in lacking corresponding @code{set} commands: | |
1323 | ||
1324 | @table @code | |
1325 | @kindex show version | |
3d3ab540 | 1326 | @cindex version number |
70b88761 | 1327 | @item show version |
18fae2a8 RP |
1328 | Show what version of @value{GDBN} is running. You should include this |
1329 | information in @value{GDBN} bug-reports. If multiple versions of @value{GDBN} are in | |
ed447b95 | 1330 | use at your site, you may occasionally want to determine which version |
18fae2a8 | 1331 | of @value{GDBN} you are running; as @value{GDBN} evolves, new commands are introduced, |
1041a570 | 1332 | and old ones may wither away. The version number is also announced |
d55320a0 | 1333 | when you start @value{GDBN}. |
70b88761 RP |
1334 | |
1335 | @kindex show copying | |
1336 | @item show copying | |
18fae2a8 | 1337 | Display information about permission for copying @value{GDBN}. |
70b88761 RP |
1338 | |
1339 | @kindex show warranty | |
1340 | @item show warranty | |
af215b1a | 1341 | Display the @sc{gnu} ``NO WARRANTY'' statement. |
70b88761 RP |
1342 | @end table |
1343 | ||
4eb4cf57 | 1344 | @node Running |
18fae2a8 | 1345 | @chapter Running Programs Under @value{GDBN} |
70b88761 | 1346 | |
ed447b95 | 1347 | When you run a program under @value{GDBN}, you must first generate |
1d7c3357 | 1348 | debugging information when you compile it. |
18fae2a8 | 1349 | @ifclear BARETARGET |
af215b1a VM |
1350 | You may start @value{GDBN} with its arguments, if any, in an environment |
1351 | of your choice. You may redirect your program's input and output, debug an | |
1d7c3357 | 1352 | already running process, or kill a child process. |
18fae2a8 | 1353 | @end ifclear |
18fae2a8 | 1354 | |
18fae2a8 | 1355 | @menu |
ed447b95 RP |
1356 | * Compilation:: Compiling for debugging |
1357 | * Starting:: Starting your program | |
1d7c3357 | 1358 | @ifclear BARETARGET |
ed447b95 RP |
1359 | * Arguments:: Your program's arguments |
1360 | * Environment:: Your program's environment | |
1361 | * Working Directory:: Your program's working directory | |
1362 | * Input/Output:: Your program's input and output | |
1363 | * Attach:: Debugging an already-running process | |
1364 | * Kill Process:: Killing the child process | |
1365 | * Process Information:: Additional process information | |
0cb95a9c | 1366 | * Threads:: Debugging programs with multiple threads |
1b0c5a4f | 1367 | * Processes:: Debugging programs with multiple processes |
18fae2a8 | 1368 | @end ifclear |
18fae2a8 | 1369 | @end menu |
70b88761 | 1370 | |
4eb4cf57 | 1371 | @node Compilation |
93928b60 | 1372 | @section Compiling for debugging |
70b88761 RP |
1373 | |
1374 | In order to debug a program effectively, you need to generate | |
1375 | debugging information when you compile it. This debugging information | |
1376 | is stored in the object file; it describes the data type of each | |
1377 | variable or function and the correspondence between source line numbers | |
1378 | and addresses in the executable code. | |
1379 | ||
1380 | To request debugging information, specify the @samp{-g} option when you run | |
1381 | the compiler. | |
1382 | ||
1383 | Many C compilers are unable to handle the @samp{-g} and @samp{-O} | |
1384 | options together. Using those compilers, you cannot generate optimized | |
1385 | executables containing debugging information. | |
1386 | ||
af215b1a | 1387 | @value{NGCC}, the @sc{gnu} C compiler, supports @samp{-g} with or without |
c7cb8acb RP |
1388 | @samp{-O}, making it possible to debug optimized code. We recommend |
1389 | that you @emph{always} use @samp{-g} whenever you compile a program. | |
1390 | You may think your program is correct, but there is no sense in pushing | |
1391 | your luck. | |
70b88761 | 1392 | |
6ca72cc6 RP |
1393 | @cindex optimized code, debugging |
1394 | @cindex debugging optimized code | |
1395 | When you debug a program compiled with @samp{-g -O}, remember that the | |
9a27b06e | 1396 | optimizer is rearranging your code; the debugger shows you what is |
93918348 | 1397 | really there. Do not be too surprised when the execution path does not |
6ca72cc6 | 1398 | exactly match your source file! An extreme example: if you define a |
9a27b06e | 1399 | variable, but never use it, @value{GDBN} never sees that |
6ca72cc6 RP |
1400 | variable---because the compiler optimizes it out of existence. |
1401 | ||
70b88761 RP |
1402 | Some things do not work as well with @samp{-g -O} as with just |
1403 | @samp{-g}, particularly on machines with instruction scheduling. If in | |
1404 | doubt, recompile with @samp{-g} alone, and if this fixes the problem, | |
af215b1a | 1405 | please report it to us as a bug (including a test case!). |
70b88761 | 1406 | |
af215b1a | 1407 | Older versions of the @sc{gnu} C compiler permitted a variant option |
18fae2a8 | 1408 | @w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this |
af215b1a | 1409 | format; if your @sc{gnu} C compiler has this option, do not use it. |
70b88761 | 1410 | |
d55320a0 | 1411 | @need 2000 |
4eb4cf57 | 1412 | @node Starting |
93928b60 | 1413 | @section Starting your program |
70b88761 RP |
1414 | @cindex starting |
1415 | @cindex running | |
1041a570 | 1416 | |
70b88761 | 1417 | @table @code |
af215b1a | 1418 | @kindex run |
70b88761 RP |
1419 | @item run |
1420 | @itemx r | |
18fae2a8 | 1421 | Use the @code{run} command to start your program under @value{GDBN}. You must |
1041a570 | 1422 | first specify the program name |
18fae2a8 | 1423 | @ifset VXWORKS |
7463aadd | 1424 | (except on VxWorks) |
18fae2a8 | 1425 | @end ifset |
ed447b95 RP |
1426 | with an argument to @value{GDBN} (@pxref{Invocation, ,Getting In and |
1427 | Out of @value{GDBN}}), or by using the @code{file} or @code{exec-file} | |
93928b60 | 1428 | command (@pxref{Files, ,Commands to specify files}). |
1041a570 | 1429 | |
70b88761 RP |
1430 | @end table |
1431 | ||
18fae2a8 | 1432 | @ifclear BARETARGET |
29a2b744 RP |
1433 | If you are running your program in an execution environment that |
1434 | supports processes, @code{run} creates an inferior process and makes | |
1435 | that process run your program. (In environments without processes, | |
1436 | @code{run} jumps to the start of your program.) | |
70b88761 RP |
1437 | |
1438 | The execution of a program is affected by certain information it | |
18fae2a8 | 1439 | receives from its superior. @value{GDBN} provides ways to specify this |
6ca72cc6 | 1440 | information, which you must do @emph{before} starting your program. (You |
9a27b06e | 1441 | can change it after starting your program, but such changes only affect |
29a2b744 | 1442 | your program the next time you start it.) This information may be |
70b88761 RP |
1443 | divided into four categories: |
1444 | ||
1445 | @table @asis | |
6ca72cc6 | 1446 | @item The @emph{arguments.} |
29a2b744 | 1447 | Specify the arguments to give your program as the arguments of the |
1041a570 RP |
1448 | @code{run} command. If a shell is available on your target, the shell |
1449 | is used to pass the arguments, so that you may use normal conventions | |
1450 | (such as wildcard expansion or variable substitution) in describing | |
1451 | the arguments. In Unix systems, you can control which shell is used | |
1452 | with the @code{SHELL} environment variable. @xref{Arguments, ,Your | |
93928b60 | 1453 | program's arguments}. |
70b88761 | 1454 | |
6ca72cc6 | 1455 | @item The @emph{environment.} |
18fae2a8 RP |
1456 | Your program normally inherits its environment from @value{GDBN}, but you can |
1457 | use the @value{GDBN} commands @code{set environment} and @code{unset | |
9a27b06e | 1458 | environment} to change parts of the environment that affect |
93928b60 | 1459 | your program. @xref{Environment, ,Your program's environment}. |
70b88761 | 1460 | |
6ca72cc6 | 1461 | @item The @emph{working directory.} |
18fae2a8 | 1462 | Your program inherits its working directory from @value{GDBN}. You can set |
93918348 | 1463 | the @value{GDBN} working directory with the @code{cd} command in @value{GDBN}. |
93928b60 | 1464 | @xref{Working Directory, ,Your program's working directory}. |
70b88761 | 1465 | |
6ca72cc6 | 1466 | @item The @emph{standard input and output.} |
70b88761 | 1467 | Your program normally uses the same device for standard input and |
18fae2a8 | 1468 | standard output as @value{GDBN} is using. You can redirect input and output |
70b88761 RP |
1469 | in the @code{run} command line, or you can use the @code{tty} command to |
1470 | set a different device for your program. | |
93928b60 | 1471 | @xref{Input/Output, ,Your program's input and output}. |
3d3ab540 RP |
1472 | |
1473 | @cindex pipes | |
29a2b744 RP |
1474 | @emph{Warning:} While input and output redirection work, you cannot use |
1475 | pipes to pass the output of the program you are debugging to another | |
18fae2a8 | 1476 | program; if you attempt this, @value{GDBN} is likely to wind up debugging the |
3d3ab540 | 1477 | wrong program. |
70b88761 | 1478 | @end table |
18fae2a8 | 1479 | @end ifclear |
70b88761 | 1480 | |
1041a570 | 1481 | When you issue the @code{run} command, your program begins to execute |
93928b60 | 1482 | immediately. @xref{Stopping, ,Stopping and continuing}, for discussion |
4eb4cf57 | 1483 | of how to arrange for your program to stop. Once your program has |
6b51acad | 1484 | stopped, you may call functions in your program, using the @code{print} |
4eb4cf57 | 1485 | or @code{call} commands. @xref{Data, ,Examining Data}. |
70b88761 | 1486 | |
9a27b06e RP |
1487 | If the modification time of your symbol file has changed since the last |
1488 | time @value{GDBN} read its symbols, @value{GDBN} discards its symbol | |
1489 | table, and reads it again. When it does this, @value{GDBN} tries to retain | |
1490 | your current breakpoints. | |
70b88761 | 1491 | |
18fae2a8 | 1492 | @ifclear BARETARGET |
4eb4cf57 | 1493 | @node Arguments |
93928b60 | 1494 | @section Your program's arguments |
70b88761 RP |
1495 | |
1496 | @cindex arguments (to your program) | |
1497 | The arguments to your program can be specified by the arguments of the | |
1498 | @code{run} command. They are passed to a shell, which expands wildcard | |
29a2b744 | 1499 | characters and performs redirection of I/O, and thence to your program. |
34ae25cd | 1500 | Your @code{SHELL} environment variable (if it exists) specifies what |
ac74588e JK |
1501 | shell @value{GDBN} uses. If you do not define @code{SHELL}, |
1502 | @value{GDBN} uses @code{/bin/sh}. | |
70b88761 RP |
1503 | |
1504 | @code{run} with no arguments uses the same arguments used by the previous | |
1505 | @code{run}, or those set by the @code{set args} command. | |
1506 | ||
1507 | @kindex set args | |
1508 | @table @code | |
1509 | @item set args | |
1510 | Specify the arguments to be used the next time your program is run. If | |
9a27b06e | 1511 | @code{set args} has no arguments, @code{run} executes your program |
e251e767 | 1512 | with no arguments. Once you have run your program with arguments, |
70b88761 RP |
1513 | using @code{set args} before the next @code{run} is the only way to run |
1514 | it again without arguments. | |
1515 | ||
70b88761 | 1516 | @kindex show args |
af215b1a | 1517 | @item show args |
70b88761 RP |
1518 | Show the arguments to give your program when it is started. |
1519 | @end table | |
1520 | ||
4eb4cf57 | 1521 | @node Environment |
93928b60 | 1522 | @section Your program's environment |
70b88761 RP |
1523 | |
1524 | @cindex environment (of your program) | |
1525 | The @dfn{environment} consists of a set of environment variables and | |
1526 | their values. Environment variables conventionally record such things as | |
1527 | your user name, your home directory, your terminal type, and your search | |
1528 | path for programs to run. Usually you set up environment variables with | |
1529 | the shell and they are inherited by all the other programs you run. When | |
29a2b744 | 1530 | debugging, it can be useful to try running your program with a modified |
18fae2a8 | 1531 | environment without having to start @value{GDBN} over again. |
70b88761 RP |
1532 | |
1533 | @table @code | |
70b88761 | 1534 | @kindex path |
af215b1a | 1535 | @item path @var{directory} |
70b88761 | 1536 | Add @var{directory} to the front of the @code{PATH} environment variable |
18fae2a8 | 1537 | (the search path for executables), for both @value{GDBN} and your program. |
70b88761 RP |
1538 | You may specify several directory names, separated by @samp{:} or |
1539 | whitespace. If @var{directory} is already in the path, it is moved to | |
9a27b06e | 1540 | the front, so it is searched sooner. |
7463aadd RP |
1541 | |
1542 | You can use the string @samp{$cwd} to refer to whatever is the current | |
d55320a0 RP |
1543 | working directory at the time @value{GDBN} searches the path. If you |
1544 | use @samp{.} instead, it refers to the directory where you executed the | |
1545 | @code{path} command. @value{GDBN} replaces @samp{.} in the | |
1546 | @var{directory} argument (with the current path) before adding | |
1547 | @var{directory} to the search path. | |
29a2b744 | 1548 | @c 'path' is explicitly nonrepeatable, but RMS points out it is silly to |
70b88761 RP |
1549 | @c document that, since repeating it would be a no-op. |
1550 | ||
70b88761 | 1551 | @kindex show paths |
af215b1a | 1552 | @item show paths |
70b88761 RP |
1553 | Display the list of search paths for executables (the @code{PATH} |
1554 | environment variable). | |
1555 | ||
70b88761 | 1556 | @kindex show environment |
af215b1a | 1557 | @item show environment @r{[}@var{varname}@r{]} |
70b88761 | 1558 | Print the value of environment variable @var{varname} to be given to |
29a2b744 | 1559 | your program when it starts. If you do not supply @var{varname}, |
70b88761 RP |
1560 | print the names and values of all environment variables to be given to |
1561 | your program. You can abbreviate @code{environment} as @code{env}. | |
1562 | ||
70b88761 | 1563 | @kindex set environment |
af215b1a | 1564 | @item set environment @var{varname} @r{[}=@r{]} @var{value} |
ed447b95 | 1565 | Set environment variable @var{varname} to @var{value}. The value |
18fae2a8 | 1566 | changes for your program only, not for @value{GDBN} itself. @var{value} may |
70b88761 RP |
1567 | be any string; the values of environment variables are just strings, and |
1568 | any interpretation is supplied by your program itself. The @var{value} | |
1569 | parameter is optional; if it is eliminated, the variable is set to a | |
1570 | null value. | |
29a2b744 | 1571 | @c "any string" here does not include leading, trailing |
70b88761 RP |
1572 | @c blanks. Gnu asks: does anyone care? |
1573 | ||
1574 | For example, this command: | |
1575 | ||
1576 | @example | |
1577 | set env USER = foo | |
1578 | @end example | |
1579 | ||
1580 | @noindent | |
1581 | tells a Unix program, when subsequently run, that its user is named | |
1582 | @samp{foo}. (The spaces around @samp{=} are used for clarity here; they | |
1583 | are not actually required.) | |
1584 | ||
70b88761 | 1585 | @kindex unset environment |
af215b1a | 1586 | @item unset environment @var{varname} |
70b88761 RP |
1587 | Remove variable @var{varname} from the environment to be passed to your |
1588 | program. This is different from @samp{set env @var{varname} =}; | |
1589 | @code{unset environment} removes the variable from the environment, | |
e251e767 | 1590 | rather than assigning it an empty value. |
70b88761 RP |
1591 | @end table |
1592 | ||
34ae25cd RP |
1593 | @emph{Warning:} @value{GDBN} runs your program using the shell indicated |
1594 | by your @code{SHELL} environment variable if it exists (or | |
1595 | @code{/bin/sh} if not). If your @code{SHELL} variable names a shell | |
1596 | that runs an initialization file---such as @file{.cshrc} for C-shell, or | |
9a27b06e | 1597 | @file{.bashrc} for BASH---any variables you set in that file affect |
34ae25cd RP |
1598 | your program. You may wish to move setting of environment variables to |
1599 | files that are only run when you sign on, such as @file{.login} or | |
1600 | @file{.profile}. | |
562a18b2 | 1601 | |
4eb4cf57 | 1602 | @node Working Directory |
93928b60 | 1603 | @section Your program's working directory |
70b88761 RP |
1604 | |
1605 | @cindex working directory (of your program) | |
1606 | Each time you start your program with @code{run}, it inherits its | |
93918348 RP |
1607 | working directory from the current working directory of @value{GDBN}. |
1608 | The @value{GDBN} working directory is initially whatever it inherited | |
1609 | from its parent process (typically the shell), but you can specify a new | |
1610 | working directory in @value{GDBN} with the @code{cd} command. | |
70b88761 | 1611 | |
18fae2a8 RP |
1612 | The @value{GDBN} working directory also serves as a default for the commands |
1613 | that specify files for @value{GDBN} to operate on. @xref{Files, ,Commands to | |
93928b60 | 1614 | specify files}. |
70b88761 RP |
1615 | |
1616 | @table @code | |
70b88761 | 1617 | @kindex cd |
af215b1a | 1618 | @item cd @var{directory} |
93918348 | 1619 | Set the @value{GDBN} working directory to @var{directory}. |
70b88761 | 1620 | |
70b88761 | 1621 | @kindex pwd |
af215b1a | 1622 | @item pwd |
93918348 | 1623 | Print the @value{GDBN} working directory. |
70b88761 RP |
1624 | @end table |
1625 | ||
4eb4cf57 | 1626 | @node Input/Output |
93928b60 | 1627 | @section Your program's input and output |
70b88761 RP |
1628 | |
1629 | @cindex redirection | |
1630 | @cindex i/o | |
1631 | @cindex terminal | |
18fae2a8 | 1632 | By default, the program you run under @value{GDBN} does input and output to |
af215b1a VM |
1633 | the same terminal that @value{GDBN} uses. @value{GDBN} switches the terminal |
1634 | to its own terminal modes to interact with you, but it records the terminal | |
70b88761 RP |
1635 | modes your program was using and switches back to them when you continue |
1636 | running your program. | |
1637 | ||
1638 | @table @code | |
70b88761 | 1639 | @kindex info terminal |
af215b1a | 1640 | @item info terminal |
93918348 | 1641 | Displays information recorded by @value{GDBN} about the terminal modes your |
70b88761 RP |
1642 | program is using. |
1643 | @end table | |
1644 | ||
29a2b744 | 1645 | You can redirect your program's input and/or output using shell |
70b88761 RP |
1646 | redirection with the @code{run} command. For example, |
1647 | ||
18fae2a8 | 1648 | @example |
70b88761 | 1649 | run > outfile |
18fae2a8 | 1650 | @end example |
70b88761 RP |
1651 | |
1652 | @noindent | |
29a2b744 | 1653 | starts your program, diverting its output to the file @file{outfile}. |
70b88761 RP |
1654 | |
1655 | @kindex tty | |
1656 | @cindex controlling terminal | |
29a2b744 | 1657 | Another way to specify where your program should do input and output is |
70b88761 RP |
1658 | with the @code{tty} command. This command accepts a file name as |
1659 | argument, and causes this file to be the default for future @code{run} | |
1660 | commands. It also resets the controlling terminal for the child | |
1661 | process, for future @code{run} commands. For example, | |
1662 | ||
1663 | @example | |
1664 | tty /dev/ttyb | |
1665 | @end example | |
1666 | ||
1667 | @noindent | |
1668 | directs that processes started with subsequent @code{run} commands | |
1669 | default to do input and output on the terminal @file{/dev/ttyb} and have | |
1670 | that as their controlling terminal. | |
1671 | ||
1672 | An explicit redirection in @code{run} overrides the @code{tty} command's | |
1673 | effect on the input/output device, but not its effect on the controlling | |
1674 | terminal. | |
1675 | ||
1676 | When you use the @code{tty} command or redirect input in the @code{run} | |
1677 | command, only the input @emph{for your program} is affected. The input | |
18fae2a8 | 1678 | for @value{GDBN} still comes from your terminal. |
70b88761 | 1679 | |
4eb4cf57 | 1680 | @node Attach |
93928b60 | 1681 | @section Debugging an already-running process |
70b88761 RP |
1682 | @kindex attach |
1683 | @cindex attach | |
1684 | ||
1685 | @table @code | |
1686 | @item attach @var{process-id} | |
1d7c3357 | 1687 | This command attaches to a running process---one that was started |
9a27b06e | 1688 | outside @value{GDBN}. (@code{info files} shows your active |
1d7c3357 RP |
1689 | targets.) The command takes as argument a process ID. The usual way to |
1690 | find out the process-id of a Unix process is with the @code{ps} utility, | |
1691 | or with the @samp{jobs -l} shell command. | |
70b88761 | 1692 | |
9a27b06e | 1693 | @code{attach} does not repeat if you press @key{RET} a second time after |
70b88761 RP |
1694 | executing the command. |
1695 | @end table | |
1696 | ||
d55320a0 RP |
1697 | To use @code{attach}, your program must be running in an environment |
1698 | which supports processes; for example, @code{attach} does not work for | |
1699 | programs on bare-board targets that lack an operating system. You must | |
1700 | also have permission to send the process a signal. | |
70b88761 RP |
1701 | |
1702 | When using @code{attach}, you should first use the @code{file} command | |
1703 | to specify the program running in the process and load its symbol table. | |
29a2b744 | 1704 | @xref{Files, ,Commands to Specify Files}. |
70b88761 | 1705 | |
18fae2a8 | 1706 | The first thing @value{GDBN} does after arranging to debug the specified |
70b88761 | 1707 | process is to stop it. You can examine and modify an attached process |
18fae2a8 | 1708 | with all the @value{GDBN} commands that are ordinarily available when you start |
70b88761 RP |
1709 | processes with @code{run}. You can insert breakpoints; you can step and |
1710 | continue; you can modify storage. If you would rather the process | |
1711 | continue running, you may use the @code{continue} command after | |
18fae2a8 | 1712 | attaching @value{GDBN} to the process. |
70b88761 RP |
1713 | |
1714 | @table @code | |
70b88761 | 1715 | @kindex detach |
af215b1a | 1716 | @item detach |
70b88761 | 1717 | When you have finished debugging the attached process, you can use the |
93918348 | 1718 | @code{detach} command to release it from @value{GDBN} control. Detaching |
70b88761 | 1719 | the process continues its execution. After the @code{detach} command, |
18fae2a8 | 1720 | that process and @value{GDBN} become completely independent once more, and you |
70b88761 | 1721 | are ready to @code{attach} another process or start one with @code{run}. |
9a27b06e | 1722 | @code{detach} does not repeat if you press @key{RET} again after |
70b88761 RP |
1723 | executing the command. |
1724 | @end table | |
1725 | ||
9a27b06e RP |
1726 | If you exit @value{GDBN} or use the @code{run} command while you have an |
1727 | attached process, you kill that process. By default, @value{GDBN} asks | |
1728 | for confirmation if you try to do either of these things; you can | |
1729 | control whether or not you need to confirm by using the @code{set | |
1730 | confirm} command (@pxref{Messages/Warnings, ,Optional warnings and | |
1731 | messages}). | |
70b88761 | 1732 | |
4eb4cf57 | 1733 | @node Kill Process |
70b88761 | 1734 | @c @group |
93928b60 | 1735 | @section Killing the child process |
70b88761 RP |
1736 | |
1737 | @table @code | |
70b88761 | 1738 | @kindex kill |
af215b1a | 1739 | @item kill |
18fae2a8 | 1740 | Kill the child process in which your program is running under @value{GDBN}. |
70b88761 RP |
1741 | @end table |
1742 | ||
1743 | This command is useful if you wish to debug a core dump instead of a | |
18fae2a8 | 1744 | running process. @value{GDBN} ignores any core dump file while your program |
70b88761 RP |
1745 | is running. |
1746 | @c @end group | |
1747 | ||
18fae2a8 RP |
1748 | On some operating systems, a program cannot be executed outside @value{GDBN} |
1749 | while you have breakpoints set on it inside @value{GDBN}. You can use the | |
29a2b744 | 1750 | @code{kill} command in this situation to permit running your program |
70b88761 RP |
1751 | outside the debugger. |
1752 | ||
1753 | The @code{kill} command is also useful if you wish to recompile and | |
29a2b744 | 1754 | relink your program, since on many systems it is impossible to modify an |
70b88761 | 1755 | executable file while it is running in a process. In this case, when you |
9a27b06e RP |
1756 | next type @code{run}, @value{GDBN} notices that the file has changed, and |
1757 | reads the symbol table again (while trying to preserve your current | |
70b88761 RP |
1758 | breakpoint settings). |
1759 | ||
4eb4cf57 | 1760 | @node Process Information |
93928b60 | 1761 | @section Additional process information |
d24e0922 RP |
1762 | |
1763 | @kindex /proc | |
1764 | @cindex process image | |
1765 | Some operating systems provide a facility called @samp{/proc} that can | |
cc9bc574 | 1766 | be used to examine the image of a running process using file-system |
18fae2a8 | 1767 | subroutines. If @value{GDBN} is configured for an operating system with this |
cc9bc574 | 1768 | facility, the command @code{info proc} is available to report on several |
af215b1a VM |
1769 | kinds of information about the process running your program. |
1770 | @code{info proc} works only on SVR4 systems that support @code{procfs}. | |
d24e0922 RP |
1771 | |
1772 | @table @code | |
d24e0922 | 1773 | @kindex info proc |
af215b1a | 1774 | @item info proc |
d24e0922 RP |
1775 | Summarize available information about the process. |
1776 | ||
d24e0922 | 1777 | @kindex info proc mappings |
af215b1a | 1778 | @item info proc mappings |
d24e0922 RP |
1779 | Report on the address ranges accessible in the program, with information |
1780 | on whether your program may read, write, or execute each range. | |
1781 | ||
d24e0922 | 1782 | @kindex info proc times |
af215b1a | 1783 | @item info proc times |
d24e0922 RP |
1784 | Starting time, user CPU time, and system CPU time for your program and |
1785 | its children. | |
1786 | ||
d24e0922 | 1787 | @kindex info proc id |
af215b1a | 1788 | @item info proc id |
93918348 RP |
1789 | Report on the process IDs related to your program: its own process ID, |
1790 | the ID of its parent, the process group ID, and the session ID. | |
d24e0922 | 1791 | |
d24e0922 | 1792 | @kindex info proc status |
af215b1a | 1793 | @item info proc status |
d24e0922 RP |
1794 | General information on the state of the process. If the process is |
1795 | stopped, this report includes the reason for stopping, and any signal | |
1796 | received. | |
cc9bc574 RP |
1797 | |
1798 | @item info proc all | |
1799 | Show all the above information about the process. | |
d24e0922 | 1800 | @end table |
0cb95a9c RP |
1801 | |
1802 | @node Threads | |
1803 | @section Debugging programs with multiple threads | |
1804 | ||
1805 | @cindex threads of execution | |
1806 | @cindex multiple threads | |
1807 | @cindex switching threads | |
1808 | In some operating systems, a single program may have more than one | |
1809 | @dfn{thread} of execution. The precise semantics of threads differ from | |
1810 | one operating system to another, but in general the threads of a single | |
1811 | program are akin to multiple processes---except that they share one | |
1812 | address space (that is, they can all examine and modify the same | |
1813 | variables). On the other hand, each thread has its own registers and | |
1814 | execution stack, and perhaps private memory. | |
1815 | ||
22b5dba5 | 1816 | @value{GDBN} provides these facilities for debugging multi-thread |
0cb95a9c RP |
1817 | programs: |
1818 | ||
1819 | @itemize @bullet | |
1820 | @item automatic notification of new threads | |
1821 | @item @samp{thread @var{threadno}}, a command to switch among threads | |
1822 | @item @samp{info threads}, a command to inquire about existing threads | |
af215b1a VM |
1823 | @item @samp{thread apply [@var{threadno}] [@var{all}] @var{args}}, |
1824 | a command to apply a command to a list of threads | |
0cb95a9c RP |
1825 | @item thread-specific breakpoints |
1826 | @end itemize | |
1827 | ||
1828 | @quotation | |
1829 | @emph{Warning:} These facilities are not yet available on every | |
1830 | @value{GDBN} configuration where the operating system supports threads. | |
1831 | If your @value{GDBN} does not support threads, these commands have no | |
1832 | effect. For example, a system without thread support shows no output | |
1833 | from @samp{info threads}, and always rejects the @code{thread} command, | |
1834 | like this: | |
1835 | ||
1836 | @smallexample | |
1837 | (@value{GDBP}) info threads | |
1838 | (@value{GDBP}) thread 1 | |
1839 | Thread ID 1 not known. Use the "info threads" command to | |
1840 | see the IDs of currently known threads. | |
1841 | @end smallexample | |
1842 | @c FIXME to implementors: how hard would it be to say "sorry, this GDB | |
1843 | @c doesn't support threads"? | |
1844 | @end quotation | |
1845 | ||
1846 | @cindex focus of debugging | |
1847 | @cindex current thread | |
1848 | The @value{GDBN} thread debugging facility allows you to observe all | |
1849 | threads while your program runs---but whenever @value{GDBN} takes | |
1850 | control, one thread in particular is always the focus of debugging. | |
1851 | This thread is called the @dfn{current thread}. Debugging commands show | |
1852 | program information from the perspective of the current thread. | |
1853 | ||
1854 | @kindex New @var{systag} | |
1855 | @cindex thread identifier (system) | |
1856 | @c FIXME-implementors!! It would be more helpful if the [New...] message | |
1857 | @c included GDB's numeric thread handle, so you could just go to that | |
1858 | @c thread without first checking `info threads'. | |
1859 | Whenever @value{GDBN} detects a new thread in your program, it displays | |
22b5dba5 RP |
1860 | the target system's identification for the thread with a message in the |
1861 | form @samp{[New @var{systag}]}. @var{systag} is a thread identifier | |
1862 | whose form varies depending on the particular system. For example, on | |
1863 | LynxOS, you might see | |
0cb95a9c RP |
1864 | |
1865 | @example | |
1866 | [New process 35 thread 27] | |
1867 | @end example | |
1868 | ||
1869 | @noindent | |
1870 | when @value{GDBN} notices a new thread. In contrast, on an SGI system, | |
1871 | the @var{systag} is simply something like @samp{process 368}, with no | |
1872 | further qualifier. | |
1873 | ||
1874 | @c FIXME!! (1) Does the [New...] message appear even for the very first | |
1875 | @c thread of a program, or does it only appear for the | |
1876 | @c second---i.e., when it becomes obvious we have a multithread | |
1877 | @c program? | |
1878 | @c (2) *Is* there necessarily a first thread always? Or do some | |
1879 | @c multithread systems permit starting a program with multiple | |
1880 | @c threads ab initio? | |
1881 | ||
1882 | @cindex thread number | |
1883 | @cindex thread identifier (GDB) | |
1884 | For debugging purposes, @value{GDBN} associates its own thread | |
1885 | number---always a single integer---with each thread in your program. | |
1886 | ||
1887 | @table @code | |
0cb95a9c | 1888 | @kindex info threads |
af215b1a | 1889 | @item info threads |
0cb95a9c RP |
1890 | Display a summary of all threads currently in your |
1891 | program. @value{GDBN} displays for each thread (in this order): | |
1892 | ||
1893 | @enumerate | |
22b5dba5 | 1894 | @item the thread number assigned by @value{GDBN} |
0cb95a9c | 1895 | |
22b5dba5 | 1896 | @item the target system's thread identifier (@var{systag}) |
0cb95a9c RP |
1897 | |
1898 | @item the current stack frame summary for that thread | |
1899 | @end enumerate | |
1900 | ||
1901 | @noindent | |
1902 | An asterisk @samp{*} to the left of the @value{GDBN} thread number | |
1903 | indicates the current thread. | |
1904 | ||
1905 | For example, | |
1906 | @end table | |
1907 | @c end table here to get a little more width for example | |
1908 | ||
1909 | @smallexample | |
1910 | (@value{GDBP}) info threads | |
1911 | 3 process 35 thread 27 0x34e5 in sigpause () | |
1912 | 2 process 35 thread 23 0x34e5 in sigpause () | |
1913 | * 1 process 35 thread 13 main (argc=1, argv=0x7ffffff8) | |
1914 | at threadtest.c:68 | |
1915 | @end smallexample | |
1916 | ||
1917 | @table @code | |
22b5dba5 | 1918 | @kindex thread @var{threadno} |
af215b1a | 1919 | @item thread @var{threadno} |
0cb95a9c RP |
1920 | Make thread number @var{threadno} the current thread. The command |
1921 | argument @var{threadno} is the internal @value{GDBN} thread number, as | |
1922 | shown in the first field of the @samp{info threads} display. | |
1923 | @value{GDBN} responds by displaying the system identifier of the thread | |
1924 | you selected, and its current stack frame summary: | |
1925 | ||
1926 | @smallexample | |
af215b1a | 1927 | @c FIXME!! This example made up; find a @value{GDBN} w/threads and get real one |
0cb95a9c RP |
1928 | (@value{GDBP}) thread 2 |
1929 | [Switching to process 35 thread 23] | |
1930 | 0x34e5 in sigpause () | |
1931 | @end smallexample | |
1932 | ||
1933 | @noindent | |
1934 | As with the @samp{[New @dots{}]} message, the form of the text after | |
1935 | @samp{Switching to} depends on your system's conventions for identifying | |
1936 | threads. | |
af215b1a VM |
1937 | |
1938 | @kindex thread apply | |
1939 | @item thread apply [@var{threadno}] [@var{all}] @var{args} | |
1940 | The @code{thread apply} command allows you to apply a command to one or | |
1941 | more threads. Specify the numbers of the threads that you want affected | |
1942 | with the command argument @var{threadno}. @var{threadno} is the internal | |
1943 | @value{GDBN} thread number, as shown in the first field of the @samp{info | |
1944 | threads} display. To apply a command to all threads, use | |
1945 | @code{thread apply all} @var{args}. | |
0cb95a9c RP |
1946 | @end table |
1947 | ||
1948 | @cindex automatic thread selection | |
1949 | @cindex switching threads automatically | |
1950 | @cindex threads, automatic switching | |
1951 | Whenever @value{GDBN} stops your program, due to a breakpoint or a | |
1952 | signal, it automatically selects the thread where that breakpoint or | |
1953 | signal happened. @value{GDBN} alerts you to the context switch with a | |
1954 | message of the form @samp{[Switching to @var{systag}]} to identify the | |
1955 | thread. | |
1956 | ||
1957 | @xref{Thread Stops,,Stopping and starting multi-thread programs}, for | |
1958 | more information about how @value{GDBN} behaves when you stop and start | |
1959 | programs with multiple threads. | |
22b5dba5 RP |
1960 | |
1961 | @xref{Set Watchpoints,,Setting watchpoints}, for information about | |
1962 | watchpoints in programs with multiple threads. | |
18fae2a8 | 1963 | @end ifclear |
d24e0922 | 1964 | |
1b0c5a4f JK |
1965 | @node Processes |
1966 | @section Debugging programs with multiple processes | |
1967 | ||
1968 | @cindex fork, debugging programs which call | |
1969 | @cindex multiple processes | |
1970 | @cindex processes, multiple | |
1971 | @value{GDBN} has no special support for debugging programs which create | |
1972 | additional processes using the @code{fork} function. When a program | |
1973 | forks, @value{GDBN} will continue to debug the parent process and the | |
1974 | child process will run unimpeded. If you have set a breakpoint in any | |
1975 | code which the child then executes, the child will get a @code{SIGTRAP} | |
1976 | signal which (unless it catches the signal) will cause it to terminate. | |
1977 | ||
1978 | However, if you want to debug the child process there is a workaround | |
1979 | which isn't too painful. Put a call to @code{sleep} in the code which | |
1980 | the child process executes after the fork. It may be useful to sleep | |
1981 | only if a certain environment variable is set, or a certain file exists, | |
1982 | so that the delay need not occur when you don't want to run @value{GDBN} | |
1983 | on the child. While the child is sleeping, use the @code{ps} program to | |
1984 | get its process ID. Then tell @value{GDBN} (a new invocation of | |
1985 | @value{GDBN} if you are also debugging the parent process) to attach to | |
1986 | the child process (see @ref{Attach}). From that point on you can debug | |
1987 | the child process just like any other process which you attached to. | |
1988 | ||
4eb4cf57 | 1989 | @node Stopping |
70b88761 RP |
1990 | @chapter Stopping and Continuing |
1991 | ||
ed447b95 | 1992 | The principal purposes of using a debugger are so that you can stop your |
29a2b744 | 1993 | program before it terminates; or so that, if your program runs into |
70b88761 RP |
1994 | trouble, you can investigate and find out why. |
1995 | ||
18fae2a8 | 1996 | Inside @value{GDBN}, your program may stop for any of several reasons, such |
1d7c3357 RP |
1997 | as |
1998 | @ifclear BARETARGET | |
1999 | a signal, | |
2000 | @end ifclear | |
2001 | a breakpoint, or reaching a new line after a @value{GDBN} | |
70b88761 RP |
2002 | command such as @code{step}. You may then examine and change |
2003 | variables, set new breakpoints or remove old ones, and then continue | |
18fae2a8 | 2004 | execution. Usually, the messages shown by @value{GDBN} provide ample |
70b88761 RP |
2005 | explanation of the status of your program---but you can also explicitly |
2006 | request this information at any time. | |
2007 | ||
2008 | @table @code | |
70b88761 | 2009 | @kindex info program |
af215b1a | 2010 | @item info program |
70b88761 | 2011 | Display information about the status of your program: whether it is |
1d7c3357 RP |
2012 | running or not, |
2013 | @ifclear BARETARGET | |
2014 | what process it is, | |
2015 | @end ifclear | |
2016 | and why it stopped. | |
70b88761 RP |
2017 | @end table |
2018 | ||
18fae2a8 RP |
2019 | @menu |
2020 | @ifclear CONLY | |
ed447b95 | 2021 | * Breakpoints:: Breakpoints, watchpoints, and exceptions |
18fae2a8 RP |
2022 | @end ifclear |
2023 | @ifset CONLY | |
ed447b95 | 2024 | * Breakpoints:: Breakpoints and watchpoints |
18fae2a8 | 2025 | @end ifset |
1d7c3357 | 2026 | @c Remnant makeinfo bug requires blank line after *successful* end-if in menu: |
18fae2a8 | 2027 | |
ed447b95 | 2028 | * Continuing and Stepping:: Resuming execution |
18fae2a8 | 2029 | @ifset POSIX |
b80282d5 | 2030 | * Signals:: Signals |
18fae2a8 | 2031 | @end ifset |
0cb95a9c RP |
2032 | @ifclear BARETARGET |
2033 | * Thread Stops:: Stopping and starting multi-thread programs | |
2034 | @end ifclear | |
18fae2a8 | 2035 | @end menu |
70b88761 | 2036 | |
1d7c3357 | 2037 | @c makeinfo node-defaulting requires adjacency of @node and sectioning cmds |
18fae2a8 RP |
2038 | @c ...hence distribute @node Breakpoints over two possible @if expansions. |
2039 | @c | |
2040 | @ifclear CONLY | |
4eb4cf57 | 2041 | @node Breakpoints |
93928b60 | 2042 | @section Breakpoints, watchpoints, and exceptions |
18fae2a8 RP |
2043 | @end ifclear |
2044 | @ifset CONLY | |
2045 | @node Breakpoints | |
93928b60 | 2046 | @section Breakpoints and watchpoints |
18fae2a8 | 2047 | @end ifset |
70b88761 RP |
2048 | |
2049 | @cindex breakpoints | |
2050 | A @dfn{breakpoint} makes your program stop whenever a certain point in | |
9a27b06e RP |
2051 | the program is reached. For each breakpoint, you can add |
2052 | conditions to control in finer detail whether your program stops. | |
70b88761 | 2053 | You can set breakpoints with the @code{break} command and its variants |
93928b60 | 2054 | (@pxref{Set Breaks, ,Setting breakpoints}), to specify the place where |
29a2b744 | 2055 | your program should stop by line number, function name or exact address |
0f153e74 | 2056 | in the program. |
18fae2a8 | 2057 | @ifclear CONLY |
af215b1a | 2058 | In languages with exception handling (such as @sc{gnu} C++), you can also set |
0cb95a9c RP |
2059 | breakpoints where an exception is raised (@pxref{Exception Handling,, |
2060 | Breakpoints and exceptions}). | |
18fae2a8 | 2061 | @end ifclear |
70b88761 | 2062 | |
af215b1a VM |
2063 | In SunOS 4.x, SVR4, and Alpha OSF/1 configurations, you can now set |
2064 | breakpoints in shared libraries before the executable is run. | |
2065 | ||
70b88761 | 2066 | @cindex watchpoints |
6ca72cc6 RP |
2067 | @cindex memory tracing |
2068 | @cindex breakpoint on memory address | |
2069 | @cindex breakpoint on variable modification | |
29a2b744 RP |
2070 | A @dfn{watchpoint} is a special breakpoint that stops your program |
2071 | when the value of an expression changes. You must use a different | |
2072 | command to set watchpoints (@pxref{Set Watchpoints, ,Setting | |
93928b60 | 2073 | watchpoints}), but aside from that, you can manage a watchpoint like |
29a2b744 | 2074 | any other breakpoint: you enable, disable, and delete both breakpoints |
1041a570 | 2075 | and watchpoints using the same commands. |
70b88761 | 2076 | |
fe715d06 | 2077 | You can arrange to have values from your program displayed automatically |
0cb95a9c RP |
2078 | whenever @value{GDBN} stops at a breakpoint. @xref{Auto Display,, |
2079 | Automatic display}. | |
fe715d06 | 2080 | |
6ca72cc6 RP |
2081 | @cindex breakpoint numbers |
2082 | @cindex numbers for breakpoints | |
18fae2a8 | 2083 | @value{GDBN} assigns a number to each breakpoint or watchpoint when you |
6ca72cc6 RP |
2084 | create it; these numbers are successive integers starting with one. In |
2085 | many of the commands for controlling various features of breakpoints you | |
2086 | use the breakpoint number to say which breakpoint you want to change. | |
2087 | Each breakpoint may be @dfn{enabled} or @dfn{disabled}; if disabled, it has | |
29a2b744 | 2088 | no effect on your program until you enable it again. |
70b88761 RP |
2089 | |
2090 | @menu | |
ed447b95 RP |
2091 | * Set Breaks:: Setting breakpoints |
2092 | * Set Watchpoints:: Setting watchpoints | |
1d7c3357 | 2093 | @ifclear CONLY |
ed447b95 | 2094 | * Exception Handling:: Breakpoints and exceptions |
1d7c3357 | 2095 | @end ifclear |
b0157555 | 2096 | |
ed447b95 RP |
2097 | * Delete Breaks:: Deleting breakpoints |
2098 | * Disabling:: Disabling breakpoints | |
2099 | * Conditions:: Break conditions | |
2100 | * Break Commands:: Breakpoint command lists | |
1d7c3357 | 2101 | @ifclear CONLY |
ed447b95 | 2102 | * Breakpoint Menus:: Breakpoint menus |
1d7c3357 | 2103 | @end ifclear |
af215b1a VM |
2104 | @c @ifclear BARETARGET |
2105 | @c * Error in Breakpoints:: ``Cannot insert breakpoints'' | |
2106 | @c @end ifclear | |
70b88761 RP |
2107 | @end menu |
2108 | ||
4eb4cf57 | 2109 | @node Set Breaks |
93928b60 | 2110 | @subsection Setting breakpoints |
70b88761 | 2111 | |
4906534f RP |
2112 | @c FIXME LMB what does GDB do if no code on line of breakpt? |
2113 | @c consider in particular declaration with/without initialization. | |
2114 | @c | |
2115 | @c FIXME 2 is there stuff on this already? break at fun start, already init? | |
2116 | ||
70b88761 RP |
2117 | @kindex break |
2118 | @kindex b | |
6ca72cc6 RP |
2119 | @kindex $bpnum |
2120 | @cindex latest breakpoint | |
2121 | Breakpoints are set with the @code{break} command (abbreviated | |
2122 | @code{b}). The debugger convenience variable @samp{$bpnum} records the | |
af215b1a | 2123 | number of the breakpoints you've set most recently; see @ref{Convenience |
93928b60 | 2124 | Vars,, Convenience variables}, for a discussion of what you can do with |
6ca72cc6 | 2125 | convenience variables. |
70b88761 RP |
2126 | |
2127 | You have several ways to say where the breakpoint should go. | |
2128 | ||
2129 | @table @code | |
2130 | @item break @var{function} | |
0f153e74 | 2131 | Set a breakpoint at entry to function @var{function}. |
18fae2a8 | 2132 | @ifclear CONLY |
0f153e74 RP |
2133 | When using source languages that permit overloading of symbols, such as |
2134 | C++, @var{function} may refer to more than one possible place to break. | |
93928b60 | 2135 | @xref{Breakpoint Menus,,Breakpoint menus}, for a discussion of that situation. |
18fae2a8 | 2136 | @end ifclear |
70b88761 RP |
2137 | |
2138 | @item break +@var{offset} | |
2139 | @itemx break -@var{offset} | |
2140 | Set a breakpoint some number of lines forward or back from the position | |
2141 | at which execution stopped in the currently selected frame. | |
2142 | ||
2143 | @item break @var{linenum} | |
2144 | Set a breakpoint at line @var{linenum} in the current source file. | |
2145 | That file is the last file whose source text was printed. This | |
9a27b06e | 2146 | breakpoint stops your program just before it executes any of the |
70b88761 RP |
2147 | code on that line. |
2148 | ||
2149 | @item break @var{filename}:@var{linenum} | |
2150 | Set a breakpoint at line @var{linenum} in source file @var{filename}. | |
2151 | ||
2152 | @item break @var{filename}:@var{function} | |
2153 | Set a breakpoint at entry to function @var{function} found in file | |
2154 | @var{filename}. Specifying a file name as well as a function name is | |
2155 | superfluous except when multiple files contain similarly named | |
2156 | functions. | |
2157 | ||
2158 | @item break *@var{address} | |
2159 | Set a breakpoint at address @var{address}. You can use this to set | |
29a2b744 | 2160 | breakpoints in parts of your program which do not have debugging |
70b88761 RP |
2161 | information or source files. |
2162 | ||
2163 | @item break | |
29a2b744 RP |
2164 | When called without any arguments, @code{break} sets a breakpoint at |
2165 | the next instruction to be executed in the selected stack frame | |
2166 | (@pxref{Stack, ,Examining the Stack}). In any selected frame but the | |
9a27b06e | 2167 | innermost, this makes your program stop as soon as control |
29a2b744 RP |
2168 | returns to that frame. This is similar to the effect of a |
2169 | @code{finish} command in the frame inside the selected frame---except | |
2170 | that @code{finish} does not leave an active breakpoint. If you use | |
9a27b06e | 2171 | @code{break} without an argument in the innermost frame, @value{GDBN} stops |
1041a570 RP |
2172 | the next time it reaches the current location; this may be useful |
2173 | inside loops. | |
70b88761 | 2174 | |
18fae2a8 | 2175 | @value{GDBN} normally ignores breakpoints when it resumes execution, until at |
70b88761 RP |
2176 | least one instruction has been executed. If it did not do this, you |
2177 | would be unable to proceed past a breakpoint without first disabling the | |
2178 | breakpoint. This rule applies whether or not the breakpoint already | |
29a2b744 | 2179 | existed when your program stopped. |
70b88761 RP |
2180 | |
2181 | @item break @dots{} if @var{cond} | |
2182 | Set a breakpoint with condition @var{cond}; evaluate the expression | |
2183 | @var{cond} each time the breakpoint is reached, and stop only if the | |
3d3ab540 | 2184 | value is nonzero---that is, if @var{cond} evaluates as true. |
1041a570 RP |
2185 | @samp{@dots{}} stands for one of the possible arguments described |
2186 | above (or no argument) specifying where to break. @xref{Conditions, | |
93928b60 | 2187 | ,Break conditions}, for more information on breakpoint conditions. |
70b88761 | 2188 | |
70b88761 | 2189 | @kindex tbreak |
af215b1a | 2190 | @item tbreak @var{args} |
70b88761 RP |
2191 | Set a breakpoint enabled only for one stop. @var{args} are the |
2192 | same as for the @code{break} command, and the breakpoint is set in the same | |
cfcafcba | 2193 | way, but the breakpoint is automatically deleted after the first time your |
93928b60 | 2194 | program stops there. @xref{Disabling, ,Disabling breakpoints}. |
70b88761 | 2195 | |
af215b1a VM |
2196 | @kindex hbreak |
2197 | @item hbreak @var{args} | |
2198 | Set a hardware-assisted breakpoint. @var{args} are the same as for the | |
2199 | @code{break} command and the breakpoint is set in the same way, but the | |
2200 | breakpoint requires hardware support and some target hardware may not | |
2201 | have this support. The main purpose of this is EPROM/ROM code | |
2202 | debugging, so you can set a breakpoint at an instruction without | |
2203 | changing the instruction. This can be used with the new trap-generation | |
2204 | provided by SPARClite DSU. DSU will generate traps when a program accesses | |
8387d6df | 2205 | some data or instruction address that is assigned to the debug registers. |
af215b1a VM |
2206 | However the hardware breakpoint registers can only take two data breakpoints, |
2207 | and @value{GDBN} will reject this command if more than two are used. | |
2208 | Delete or disable usused hardware breakpoints before setting | |
2209 | new ones. @xref{Conditions, ,Break conditions}. | |
2210 | ||
2211 | @kindex thbreak | |
2212 | @item thbreak @var{args} | |
2213 | Set a hardware-assisted breakpoint enabled only for one stop. @var{args} | |
2214 | are the same as for the @code{hbreak} command and the breakpoint is set in | |
2215 | the same way. However, like the @code{tbreak} command, | |
2216 | the breakpoint is automatically deleted after the | |
2217 | first time your program stops there. Also, like the @code{hbreak} | |
2218 | command, the breakpoint requires hardware support and some target hardware | |
2219 | may not have this support. @xref{Disabling, ,Disabling breakpoints}. | |
2220 | Also @xref{Conditions, ,Break conditions}. | |
2221 | ||
70b88761 RP |
2222 | @kindex rbreak |
2223 | @cindex regular expression | |
af215b1a | 2224 | @item rbreak @var{regex} |
4906534f | 2225 | @c FIXME what kind of regexp? |
70b88761 | 2226 | Set breakpoints on all functions matching the regular expression |
b80282d5 | 2227 | @var{regex}. This command |
70b88761 | 2228 | sets an unconditional breakpoint on all matches, printing a list of all |
b1955f0b RP |
2229 | breakpoints it set. Once these breakpoints are set, they are treated |
2230 | just like the breakpoints set with the @code{break} command. You can | |
2231 | delete them, disable them, or make them conditional the same way as any | |
2232 | other breakpoint. | |
70b88761 | 2233 | |
18fae2a8 | 2234 | @ifclear CONLY |
b80282d5 RP |
2235 | When debugging C++ programs, @code{rbreak} is useful for setting |
2236 | breakpoints on overloaded functions that are not members of any special | |
2237 | classes. | |
18fae2a8 | 2238 | @end ifclear |
b80282d5 | 2239 | |
70b88761 | 2240 | @kindex info breakpoints |
c338a2fd | 2241 | @cindex @code{$_} and @code{info breakpoints} |
70b88761 | 2242 | @item info breakpoints @r{[}@var{n}@r{]} |
6ca72cc6 RP |
2243 | @itemx info break @r{[}@var{n}@r{]} |
2244 | @itemx info watchpoints @r{[}@var{n}@r{]} | |
2245 | Print a table of all breakpoints and watchpoints set and not | |
2246 | deleted, with the following columns for each breakpoint: | |
2247 | ||
2248 | @table @emph | |
2249 | @item Breakpoint Numbers | |
2250 | @item Type | |
2251 | Breakpoint or watchpoint. | |
2252 | @item Disposition | |
2253 | Whether the breakpoint is marked to be disabled or deleted when hit. | |
2254 | @item Enabled or Disabled | |
d24e0922 | 2255 | Enabled breakpoints are marked with @samp{y}. @samp{n} marks breakpoints |
6ca72cc6 RP |
2256 | that are not enabled. |
2257 | @item Address | |
2258 | Where the breakpoint is in your program, as a memory address | |
2259 | @item What | |
2260 | Where the breakpoint is in the source for your program, as a file and | |
2261 | line number. | |
2262 | @end table | |
2263 | ||
2264 | @noindent | |
d55320a0 RP |
2265 | If a breakpoint is conditional, @code{info break} shows the condition on |
2266 | the line following the affected breakpoint; breakpoint commands, if any, | |
2267 | are listed after that. | |
6ca72cc6 RP |
2268 | |
2269 | @noindent | |
2270 | @code{info break} with a breakpoint | |
29a2b744 RP |
2271 | number @var{n} as argument lists only that breakpoint. The |
2272 | convenience variable @code{$_} and the default examining-address for | |
2273 | the @code{x} command are set to the address of the last breakpoint | |
93928b60 | 2274 | listed (@pxref{Memory, ,Examining memory}). |
af215b1a VM |
2275 | |
2276 | @noindent | |
2277 | @code{info break} now displays a count of the number of times the | |
2278 | breakpoint has been hit. This is especially useful in conjunction with | |
2279 | the @code{ignore} command. You can ignore a large number of breakpoint | |
2280 | hits, look at the breakpoint info to see how many times the | |
2281 | breakpoint was hit, and then run again, ignoring one less than that | |
2282 | number. This will get you quickly to the last hit of that breakpoint. | |
1041a570 | 2283 | @end table |
70b88761 | 2284 | |
18fae2a8 | 2285 | @value{GDBN} allows you to set any number of breakpoints at the same place in |
1041a570 RP |
2286 | your program. There is nothing silly or meaningless about this. When |
2287 | the breakpoints are conditional, this is even useful | |
93928b60 | 2288 | (@pxref{Conditions, ,Break conditions}). |
70b88761 | 2289 | |
6ca72cc6 | 2290 | @cindex negative breakpoint numbers |
18fae2a8 RP |
2291 | @cindex internal @value{GDBN} breakpoints |
2292 | @value{GDBN} itself sometimes sets breakpoints in your program for special | |
6ca72cc6 RP |
2293 | purposes, such as proper handling of @code{longjmp} (in C programs). |
2294 | These internal breakpoints are assigned negative numbers, starting with | |
5a2c1d85 | 2295 | @code{-1}; @samp{info breakpoints} does not display them. |
d48da190 | 2296 | |
18fae2a8 | 2297 | You can see these breakpoints with the @value{GDBN} maintenance command |
5a2c1d85 | 2298 | @samp{maint info breakpoints}. |
6ca72cc6 RP |
2299 | |
2300 | @table @code | |
d48da190 RP |
2301 | @kindex maint info breakpoints |
2302 | @item maint info breakpoints | |
6ca72cc6 | 2303 | Using the same format as @samp{info breakpoints}, display both the |
18fae2a8 | 2304 | breakpoints you've set explicitly, and those @value{GDBN} is using for |
6ca72cc6 RP |
2305 | internal purposes. Internal breakpoints are shown with negative |
2306 | breakpoint numbers. The type column identifies what kind of breakpoint | |
2307 | is shown: | |
2308 | ||
2309 | @table @code | |
2310 | @item breakpoint | |
2311 | Normal, explicitly set breakpoint. | |
2312 | ||
2313 | @item watchpoint | |
2314 | Normal, explicitly set watchpoint. | |
2315 | ||
2316 | @item longjmp | |
2317 | Internal breakpoint, used to handle correctly stepping through | |
2318 | @code{longjmp} calls. | |
2319 | ||
2320 | @item longjmp resume | |
2321 | Internal breakpoint at the target of a @code{longjmp}. | |
2322 | ||
2323 | @item until | |
18fae2a8 | 2324 | Temporary internal breakpoint used by the @value{GDBN} @code{until} command. |
6ca72cc6 RP |
2325 | |
2326 | @item finish | |
18fae2a8 | 2327 | Temporary internal breakpoint used by the @value{GDBN} @code{finish} command. |
6ca72cc6 RP |
2328 | @end table |
2329 | ||
2330 | @end table | |
2331 | ||
2332 | ||
4eb4cf57 | 2333 | @node Set Watchpoints |
93928b60 | 2334 | @subsection Setting watchpoints |
70b88761 | 2335 | @cindex setting watchpoints |
1041a570 | 2336 | |
70b88761 | 2337 | You can use a watchpoint to stop execution whenever the value of an |
e251e767 | 2338 | expression changes, without having to predict a particular place |
70b88761 RP |
2339 | where this may happen. |
2340 | ||
2341 | Watchpoints currently execute two orders of magnitude more slowly than | |
6b51acad | 2342 | other breakpoints, but this can be well worth it to catch errors where |
9a27b06e RP |
2343 | you have no clue what part of your program is the culprit. |
2344 | ||
af215b1a VM |
2345 | @c FIXME - did Stan mean to @ignore this out? |
2346 | @ignore | |
9a27b06e | 2347 | Some processors provide special hardware to support watchpoint |
f886dc0f SS |
2348 | evaluation; @value{GDBN} will use such hardware if it is available, |
2349 | and if the support code has been added for that configuration. | |
af215b1a | 2350 | @end ignore |
70b88761 RP |
2351 | |
2352 | @table @code | |
e251e767 | 2353 | @kindex watch |
70b88761 | 2354 | @item watch @var{expr} |
af215b1a VM |
2355 | Set a watchpoint for an expression. @value{GDBN} will break when @var{expr} |
2356 | is written into by the program and its value changes. | |
2357 | This can be used with the new trap-generation provided by | |
2358 | SPARClite DSU. DSU will generate traps when a program accesses | |
8387d6df | 2359 | some data or instruction address that is assigned to the debug registers. |
af215b1a VM |
2360 | For the data addresses, DSU facilitates the @code{watch} command. |
2361 | However the hardware breakpoint registers can only take two data watchpoints, | |
2362 | and both watchpoints must be the same kind. For example, you can set two | |
2363 | watchpoints with @code{watch} commands, two with @code{rwatch} | |
2364 | commands, @strong{or} two with @code{awatch} commands, but you cannot set one | |
2365 | watchpoint with one command and the other with a different command. | |
2366 | @value{GBDN} will reject the command if you try to mix watchpoints. | |
2367 | Delete or disable unused watchpoint commands before setting new ones. | |
2368 | ||
2369 | @kindex rwatch | |
2370 | @item rwatch @var{expr} | |
2371 | Set a watchpoint that will break when watch @var{args} is read by the program. | |
2372 | If you use both watchpoints, both must be set with the @code{rwatch} | |
2373 | command. | |
2374 | ||
2375 | @kindex awatch | |
2376 | @item awatch @var{expr} | |
2377 | Set a watchpoint that will break when @var{args} is read and written into | |
2378 | by the program. If you use both watchpoints, both must be set with the | |
2379 | @code{awatch} command. | |
70b88761 RP |
2380 | |
2381 | @kindex info watchpoints | |
2382 | @item info watchpoints | |
6ca72cc6 RP |
2383 | This command prints a list of watchpoints and breakpoints; it is the |
2384 | same as @code{info break}. | |
70b88761 RP |
2385 | @end table |
2386 | ||
0cb95a9c RP |
2387 | @ifclear BARETARGET |
2388 | @quotation | |
2389 | @cindex watchpoints and threads | |
2390 | @cindex threads and watchpoints | |
2391 | @emph{Warning:} in multi-thread programs, watchpoints have only limited | |
2392 | usefulness. With the current watchpoint implementation, @value{GDBN} | |
2393 | can only watch the value of an expression @emph{in a single thread}. If | |
2394 | you are confident that the expression can only change due to the current | |
9a27b06e RP |
2395 | thread's activity (and if you are also confident that no other thread |
2396 | can become current), then you can use watchpoints as usual. However, | |
0cb95a9c RP |
2397 | @value{GDBN} may not notice when a non-current thread's activity changes |
2398 | the expression. | |
2399 | @end quotation | |
2400 | @end ifclear | |
2401 | ||
1d7c3357 | 2402 | @ifclear CONLY |
4eb4cf57 | 2403 | @node Exception Handling |
93928b60 | 2404 | @subsection Breakpoints and exceptions |
70b88761 RP |
2405 | @cindex exception handlers |
2406 | ||
af215b1a | 2407 | Some languages, such as @sc{gnu} C++, implement exception handling. You can |
18fae2a8 | 2408 | use @value{GDBN} to examine what caused your program to raise an exception, |
29a2b744 | 2409 | and to list the exceptions your program is prepared to handle at a |
70b88761 RP |
2410 | given point in time. |
2411 | ||
2412 | @table @code | |
70b88761 | 2413 | @kindex catch |
af215b1a | 2414 | @item catch @var{exceptions} |
70b88761 RP |
2415 | You can set breakpoints at active exception handlers by using the |
2416 | @code{catch} command. @var{exceptions} is a list of names of exceptions | |
2417 | to catch. | |
2418 | @end table | |
2419 | ||
29a2b744 | 2420 | You can use @code{info catch} to list active exception handlers. |
93928b60 | 2421 | @xref{Frame Info, ,Information about a frame}. |
70b88761 | 2422 | |
9a27b06e | 2423 | There are currently some limitations to exception handling in @value{GDBN}: |
70b88761 RP |
2424 | |
2425 | @itemize @bullet | |
2426 | @item | |
18fae2a8 | 2427 | If you call a function interactively, @value{GDBN} normally returns |
70b88761 RP |
2428 | control to you when the function has finished executing. If the call |
2429 | raises an exception, however, the call may bypass the mechanism that | |
29a2b744 | 2430 | returns control to you and cause your program to simply continue |
18fae2a8 | 2431 | running until it hits a breakpoint, catches a signal that @value{GDBN} is |
70b88761 | 2432 | listening for, or exits. |
9a27b06e | 2433 | |
70b88761 RP |
2434 | @item |
2435 | You cannot raise an exception interactively. | |
9a27b06e | 2436 | |
70b88761 | 2437 | @item |
9a27b06e | 2438 | You cannot install an exception handler interactively. |
70b88761 RP |
2439 | @end itemize |
2440 | ||
2441 | @cindex raise exceptions | |
2442 | Sometimes @code{catch} is not the best way to debug exception handling: | |
29a2b744 | 2443 | if you need to know exactly where an exception is raised, it is better to |
70b88761 RP |
2444 | stop @emph{before} the exception handler is called, since that way you |
2445 | can see the stack before any unwinding takes place. If you set a | |
2446 | breakpoint in an exception handler instead, it may not be easy to find | |
2447 | out where the exception was raised. | |
2448 | ||
2449 | To stop just before an exception handler is called, you need some | |
af215b1a | 2450 | knowledge of the implementation. In the case of @sc{gnu} C++, exceptions are |
70b88761 RP |
2451 | raised by calling a library function named @code{__raise_exception} |
2452 | which has the following ANSI C interface: | |
2453 | ||
2454 | @example | |
b80282d5 | 2455 | /* @var{addr} is where the exception identifier is stored. |
70b88761 RP |
2456 | ID is the exception identifier. */ |
2457 | void __raise_exception (void **@var{addr}, void *@var{id}); | |
2458 | @end example | |
2459 | ||
2460 | @noindent | |
2461 | To make the debugger catch all exceptions before any stack | |
2462 | unwinding takes place, set a breakpoint on @code{__raise_exception} | |
93928b60 | 2463 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and exceptions}). |
70b88761 | 2464 | |
93928b60 | 2465 | With a conditional breakpoint (@pxref{Conditions, ,Break conditions}) |
29a2b744 RP |
2466 | that depends on the value of @var{id}, you can stop your program when |
2467 | a specific exception is raised. You can use multiple conditional | |
2468 | breakpoints to stop your program when any of a number of exceptions are | |
2469 | raised. | |
1d7c3357 | 2470 | @end ifclear |
70b88761 | 2471 | |
4eb4cf57 | 2472 | @node Delete Breaks |
93928b60 | 2473 | @subsection Deleting breakpoints |
70b88761 RP |
2474 | |
2475 | @cindex clearing breakpoints, watchpoints | |
2476 | @cindex deleting breakpoints, watchpoints | |
2477 | It is often necessary to eliminate a breakpoint or watchpoint once it | |
29a2b744 | 2478 | has done its job and you no longer want your program to stop there. This |
70b88761 RP |
2479 | is called @dfn{deleting} the breakpoint. A breakpoint that has been |
2480 | deleted no longer exists; it is forgotten. | |
2481 | ||
2482 | With the @code{clear} command you can delete breakpoints according to | |
29a2b744 | 2483 | where they are in your program. With the @code{delete} command you can |
70b88761 RP |
2484 | delete individual breakpoints or watchpoints by specifying their |
2485 | breakpoint numbers. | |
2486 | ||
18fae2a8 | 2487 | It is not necessary to delete a breakpoint to proceed past it. @value{GDBN} |
70b88761 RP |
2488 | automatically ignores breakpoints on the first instruction to be executed |
2489 | when you continue execution without changing the execution address. | |
2490 | ||
2491 | @table @code | |
2492 | @item clear | |
2493 | @kindex clear | |
2494 | Delete any breakpoints at the next instruction to be executed in the | |
93928b60 | 2495 | selected stack frame (@pxref{Selection, ,Selecting a frame}). When |
29a2b744 RP |
2496 | the innermost frame is selected, this is a good way to delete a |
2497 | breakpoint where your program just stopped. | |
70b88761 RP |
2498 | |
2499 | @item clear @var{function} | |
2500 | @itemx clear @var{filename}:@var{function} | |
2501 | Delete any breakpoints set at entry to the function @var{function}. | |
2502 | ||
2503 | @item clear @var{linenum} | |
2504 | @itemx clear @var{filename}:@var{linenum} | |
2505 | Delete any breakpoints set at or within the code of the specified line. | |
2506 | ||
70b88761 RP |
2507 | @cindex delete breakpoints |
2508 | @kindex delete | |
2509 | @kindex d | |
af215b1a | 2510 | @item delete @r{[}breakpoints@r{]} @r{[}@var{bnums}@dots{}@r{]} |
70b88761 | 2511 | Delete the breakpoints or watchpoints of the numbers specified as |
18fae2a8 | 2512 | arguments. If no argument is specified, delete all breakpoints (@value{GDBN} |
1041a570 | 2513 | asks confirmation, unless you have @code{set confirm off}). You |
70b88761 RP |
2514 | can abbreviate this command as @code{d}. |
2515 | @end table | |
2516 | ||
4eb4cf57 | 2517 | @node Disabling |
93928b60 | 2518 | @subsection Disabling breakpoints |
70b88761 | 2519 | |
af215b1a VM |
2520 | @kindex disable breakpoints |
2521 | @kindex enable breakpoints | |
70b88761 RP |
2522 | Rather than deleting a breakpoint or watchpoint, you might prefer to |
2523 | @dfn{disable} it. This makes the breakpoint inoperative as if it had | |
2524 | been deleted, but remembers the information on the breakpoint so that | |
2525 | you can @dfn{enable} it again later. | |
2526 | ||
2527 | You disable and enable breakpoints and watchpoints with the | |
2528 | @code{enable} and @code{disable} commands, optionally specifying one or | |
2529 | more breakpoint numbers as arguments. Use @code{info break} or | |
2530 | @code{info watch} to print a list of breakpoints or watchpoints if you | |
29a2b744 | 2531 | do not know which numbers to use. |
70b88761 RP |
2532 | |
2533 | A breakpoint or watchpoint can have any of four different states of | |
2534 | enablement: | |
2535 | ||
2536 | @itemize @bullet | |
2537 | @item | |
9a27b06e | 2538 | Enabled. The breakpoint stops your program. A breakpoint set |
70b88761 RP |
2539 | with the @code{break} command starts out in this state. |
2540 | @item | |
29a2b744 | 2541 | Disabled. The breakpoint has no effect on your program. |
70b88761 | 2542 | @item |
9a27b06e RP |
2543 | Enabled once. The breakpoint stops your program, but then becomes |
2544 | disabled. A breakpoint set with the @code{tbreak} command starts out in | |
2545 | this state. | |
70b88761 | 2546 | @item |
9a27b06e RP |
2547 | Enabled for deletion. The breakpoint stops your program, but |
2548 | immediately after it does so it is deleted permanently. | |
70b88761 RP |
2549 | @end itemize |
2550 | ||
2551 | You can use the following commands to enable or disable breakpoints and | |
2552 | watchpoints: | |
2553 | ||
2554 | @table @code | |
70b88761 RP |
2555 | @kindex disable breakpoints |
2556 | @kindex disable | |
2557 | @kindex dis | |
af215b1a | 2558 | @item disable @r{[}breakpoints@r{]} @r{[}@var{bnums}@dots{}@r{]} |
70b88761 RP |
2559 | Disable the specified breakpoints---or all breakpoints, if none are |
2560 | listed. A disabled breakpoint has no effect but is not forgotten. All | |
2561 | options such as ignore-counts, conditions and commands are remembered in | |
2562 | case the breakpoint is enabled again later. You may abbreviate | |
2563 | @code{disable} as @code{dis}. | |
2564 | ||
70b88761 RP |
2565 | @kindex enable breakpoints |
2566 | @kindex enable | |
af215b1a | 2567 | @item enable @r{[}breakpoints@r{]} @r{[}@var{bnums}@dots{}@r{]} |
70b88761 | 2568 | Enable the specified breakpoints (or all defined breakpoints). They |
29a2b744 | 2569 | become effective once again in stopping your program. |
70b88761 RP |
2570 | |
2571 | @item enable @r{[}breakpoints@r{]} once @var{bnums}@dots{} | |
9a27b06e RP |
2572 | Enable the specified breakpoints temporarily. @value{GDBN} disables any |
2573 | of these breakpoints immediately after stopping your program. | |
70b88761 RP |
2574 | |
2575 | @item enable @r{[}breakpoints@r{]} delete @var{bnums}@dots{} | |
9a27b06e RP |
2576 | Enable the specified breakpoints to work once, then die. @value{GDBN} |
2577 | deletes any of these breakpoints as soon as your program stops there. | |
70b88761 RP |
2578 | @end table |
2579 | ||
af215b1a | 2580 | Except for a breakpoint set with @code{tbreak} (@pxref{Set Breaks, |
93928b60 RP |
2581 | ,Setting breakpoints}), breakpoints that you set are initially enabled; |
2582 | subsequently, they become disabled or enabled only when you use one of | |
2583 | the commands above. (The command @code{until} can set and delete a | |
9a27b06e | 2584 | breakpoint of its own, but it does not change the state of your other |
93928b60 RP |
2585 | breakpoints; see @ref{Continuing and Stepping, ,Continuing and |
2586 | stepping}.) | |
70b88761 | 2587 | |
4eb4cf57 | 2588 | @node Conditions |
93928b60 | 2589 | @subsection Break conditions |
70b88761 RP |
2590 | @cindex conditional breakpoints |
2591 | @cindex breakpoint conditions | |
2592 | ||
4906534f RP |
2593 | @c FIXME what is scope of break condition expr? Context where wanted? |
2594 | @c in particular for a watchpoint? | |
29a2b744 | 2595 | The simplest sort of breakpoint breaks every time your program reaches a |
70b88761 RP |
2596 | specified place. You can also specify a @dfn{condition} for a |
2597 | breakpoint. A condition is just a Boolean expression in your | |
1041a570 RP |
2598 | programming language (@pxref{Expressions, ,Expressions}). A breakpoint with |
2599 | a condition evaluates the expression each time your program reaches it, | |
2600 | and your program stops only if the condition is @emph{true}. | |
3d3ab540 RP |
2601 | |
2602 | This is the converse of using assertions for program validation; in that | |
2603 | situation, you want to stop when the assertion is violated---that is, | |
2604 | when the condition is false. In C, if you want to test an assertion expressed | |
e251e767 | 2605 | by the condition @var{assert}, you should set the condition |
3d3ab540 | 2606 | @samp{! @var{assert}} on the appropriate breakpoint. |
70b88761 RP |
2607 | |
2608 | Conditions are also accepted for watchpoints; you may not need them, | |
2609 | since a watchpoint is inspecting the value of an expression anyhow---but | |
2610 | it might be simpler, say, to just set a watchpoint on a variable name, | |
2611 | and specify a condition that tests whether the new value is an interesting | |
e251e767 | 2612 | one. |
70b88761 | 2613 | |
29a2b744 | 2614 | Break conditions can have side effects, and may even call functions in |
70b88761 | 2615 | your program. This can be useful, for example, to activate functions |
29a2b744 RP |
2616 | that log program progress, or to use your own print functions to |
2617 | format special data structures. The effects are completely predictable | |
2618 | unless there is another enabled breakpoint at the same address. (In | |
18fae2a8 | 2619 | that case, @value{GDBN} might see the other breakpoint first and stop your |
29a2b744 RP |
2620 | program without checking the condition of this one.) Note that |
2621 | breakpoint commands are usually more convenient and flexible for the | |
2622 | purpose of performing side effects when a breakpoint is reached | |
93928b60 | 2623 | (@pxref{Break Commands, ,Breakpoint command lists}). |
70b88761 RP |
2624 | |
2625 | Break conditions can be specified when a breakpoint is set, by using | |
29a2b744 | 2626 | @samp{if} in the arguments to the @code{break} command. @xref{Set |
93928b60 | 2627 | Breaks, ,Setting breakpoints}. They can also be changed at any time |
29a2b744 RP |
2628 | with the @code{condition} command. The @code{watch} command does not |
2629 | recognize the @code{if} keyword; @code{condition} is the only way to | |
2630 | impose a further condition on a watchpoint. | |
70b88761 | 2631 | |
e251e767 | 2632 | @table @code |
e251e767 | 2633 | @kindex condition |
af215b1a | 2634 | @item condition @var{bnum} @var{expression} |
70b88761 | 2635 | Specify @var{expression} as the break condition for breakpoint or |
9a27b06e RP |
2636 | watchpoint number @var{bnum}. After you set a condition, breakpoint |
2637 | @var{bnum} stops your program only if the value of @var{expression} is | |
2638 | true (nonzero, in C). When you use @code{condition}, @value{GDBN} | |
2639 | checks @var{expression} immediately for syntactic correctness, and to | |
2640 | determine whether symbols in it have referents in the context of your | |
2641 | breakpoint. | |
29a2b744 | 2642 | @c FIXME so what does GDB do if there is no referent? Moreover, what |
4906534f | 2643 | @c about watchpoints? |
18fae2a8 | 2644 | @value{GDBN} does |
70b88761 | 2645 | not actually evaluate @var{expression} at the time the @code{condition} |
1041a570 | 2646 | command is given, however. @xref{Expressions, ,Expressions}. |
70b88761 RP |
2647 | |
2648 | @item condition @var{bnum} | |
2649 | Remove the condition from breakpoint number @var{bnum}. It becomes | |
2650 | an ordinary unconditional breakpoint. | |
2651 | @end table | |
2652 | ||
2653 | @cindex ignore count (of breakpoint) | |
2654 | A special case of a breakpoint condition is to stop only when the | |
2655 | breakpoint has been reached a certain number of times. This is so | |
2656 | useful that there is a special way to do it, using the @dfn{ignore | |
2657 | count} of the breakpoint. Every breakpoint has an ignore count, which | |
2658 | is an integer. Most of the time, the ignore count is zero, and | |
29a2b744 | 2659 | therefore has no effect. But if your program reaches a breakpoint whose |
70b88761 RP |
2660 | ignore count is positive, then instead of stopping, it just decrements |
2661 | the ignore count by one and continues. As a result, if the ignore count | |
9a27b06e RP |
2662 | value is @var{n}, the breakpoint does not stop the next @var{n} times |
2663 | your program reaches it. | |
70b88761 RP |
2664 | |
2665 | @table @code | |
70b88761 | 2666 | @kindex ignore |
af215b1a | 2667 | @item ignore @var{bnum} @var{count} |
70b88761 RP |
2668 | Set the ignore count of breakpoint number @var{bnum} to @var{count}. |
2669 | The next @var{count} times the breakpoint is reached, your program's | |
9a27b06e | 2670 | execution does not stop; other than to decrement the ignore count, @value{GDBN} |
70b88761 RP |
2671 | takes no action. |
2672 | ||
2673 | To make the breakpoint stop the next time it is reached, specify | |
2674 | a count of zero. | |
2675 | ||
d55320a0 RP |
2676 | When you use @code{continue} to resume execution of your program from a |
2677 | breakpoint, you can specify an ignore count directly as an argument to | |
2678 | @code{continue}, rather than using @code{ignore}. @xref{Continuing and | |
2679 | Stepping,,Continuing and stepping}. | |
70b88761 | 2680 | |
9a27b06e RP |
2681 | If a breakpoint has a positive ignore count and a condition, the |
2682 | condition is not checked. Once the ignore count reaches zero, | |
2683 | @value{GDBN} resumes checking the condition. | |
70b88761 | 2684 | |
29a2b744 | 2685 | You could achieve the effect of the ignore count with a condition such |
18fae2a8 | 2686 | as @w{@samp{$foo-- <= 0}} using a debugger convenience variable that |
1041a570 | 2687 | is decremented each time. @xref{Convenience Vars, ,Convenience |
93928b60 | 2688 | variables}. |
d55320a0 | 2689 | @end table |
70b88761 | 2690 | |
4eb4cf57 | 2691 | @node Break Commands |
93928b60 | 2692 | @subsection Breakpoint command lists |
70b88761 RP |
2693 | |
2694 | @cindex breakpoint commands | |
2695 | You can give any breakpoint (or watchpoint) a series of commands to | |
29a2b744 | 2696 | execute when your program stops due to that breakpoint. For example, you |
70b88761 RP |
2697 | might want to print the values of certain expressions, or enable other |
2698 | breakpoints. | |
2699 | ||
2700 | @table @code | |
af215b1a VM |
2701 | @kindex commands |
2702 | @kindex end | |
70b88761 RP |
2703 | @item commands @r{[}@var{bnum}@r{]} |
2704 | @itemx @dots{} @var{command-list} @dots{} | |
2705 | @itemx end | |
70b88761 RP |
2706 | Specify a list of commands for breakpoint number @var{bnum}. The commands |
2707 | themselves appear on the following lines. Type a line containing just | |
2708 | @code{end} to terminate the commands. | |
2709 | ||
203eea5d RP |
2710 | To remove all commands from a breakpoint, type @code{commands} and |
2711 | follow it immediately with @code{end}; that is, give no commands. | |
70b88761 RP |
2712 | |
2713 | With no @var{bnum} argument, @code{commands} refers to the last | |
2714 | breakpoint or watchpoint set (not to the breakpoint most recently | |
2715 | encountered). | |
2716 | @end table | |
2717 | ||
18fae2a8 | 2718 | Pressing @key{RET} as a means of repeating the last @value{GDBN} command is |
70b88761 RP |
2719 | disabled within a @var{command-list}. |
2720 | ||
29a2b744 | 2721 | You can use breakpoint commands to start your program up again. Simply |
70b88761 | 2722 | use the @code{continue} command, or @code{step}, or any other command |
fe715d06 RP |
2723 | that resumes execution. |
2724 | ||
2725 | Any other commands in the command list, after a command that resumes | |
2726 | execution, are ignored. This is because any time you resume execution | |
2727 | (even with a simple @code{next} or @code{step}), you may encounter | |
2728 | another breakpoint---which could have its own command list, leading to | |
2729 | ambiguities about which list to execute. | |
70b88761 RP |
2730 | |
2731 | @kindex silent | |
fe715d06 RP |
2732 | If the first command you specify in a command list is @code{silent}, the |
2733 | usual message about stopping at a breakpoint is not printed. This may | |
2734 | be desirable for breakpoints that are to print a specific message and | |
2735 | then continue. If none of the remaining commands print anything, you | |
9a27b06e | 2736 | see no sign that the breakpoint was reached. @code{silent} is |
fe715d06 | 2737 | meaningful only at the beginning of a breakpoint command list. |
70b88761 | 2738 | |
d55320a0 RP |
2739 | The commands @code{echo}, @code{output}, and @code{printf} allow you to |
2740 | print precisely controlled output, and are often useful in silent | |
2741 | breakpoints. @xref{Output, ,Commands for controlled output}. | |
70b88761 RP |
2742 | |
2743 | For example, here is how you could use breakpoint commands to print the | |
2744 | value of @code{x} at entry to @code{foo} whenever @code{x} is positive. | |
2745 | ||
18fae2a8 | 2746 | @example |
70b88761 RP |
2747 | break foo if x>0 |
2748 | commands | |
2749 | silent | |
d55320a0 | 2750 | printf "x is %d\n",x |
70b88761 RP |
2751 | cont |
2752 | end | |
18fae2a8 | 2753 | @end example |
70b88761 RP |
2754 | |
2755 | One application for breakpoint commands is to compensate for one bug so | |
2756 | you can test for another. Put a breakpoint just after the erroneous line | |
2757 | of code, give it a condition to detect the case in which something | |
2758 | erroneous has been done, and give it commands to assign correct values | |
2759 | to any variables that need them. End with the @code{continue} command | |
29a2b744 | 2760 | so that your program does not stop, and start with the @code{silent} |
70b88761 RP |
2761 | command so that no output is produced. Here is an example: |
2762 | ||
2763 | @example | |
2764 | break 403 | |
2765 | commands | |
2766 | silent | |
2767 | set x = y + 4 | |
2768 | cont | |
2769 | end | |
2770 | @end example | |
2771 | ||
1d7c3357 | 2772 | @ifclear CONLY |
4eb4cf57 | 2773 | @node Breakpoint Menus |
93928b60 | 2774 | @subsection Breakpoint menus |
b80282d5 | 2775 | @cindex overloading |
e251e767 | 2776 | @cindex symbol overloading |
70b88761 RP |
2777 | |
2778 | Some programming languages (notably C++) permit a single function name | |
2779 | to be defined several times, for application in different contexts. | |
2780 | This is called @dfn{overloading}. When a function name is overloaded, | |
18fae2a8 | 2781 | @samp{break @var{function}} is not enough to tell @value{GDBN} where you want |
9a27b06e | 2782 | a breakpoint. If you realize this is a problem, you can use |
6f3ec223 | 2783 | something like @samp{break @var{function}(@var{types})} to specify which |
18fae2a8 | 2784 | particular version of the function you want. Otherwise, @value{GDBN} offers |
6f3ec223 RP |
2785 | you a menu of numbered choices for different possible breakpoints, and |
2786 | waits for your selection with the prompt @samp{>}. The first two | |
2787 | options are always @samp{[0] cancel} and @samp{[1] all}. Typing @kbd{1} | |
2788 | sets a breakpoint at each definition of @var{function}, and typing | |
2789 | @kbd{0} aborts the @code{break} command without setting any new | |
2790 | breakpoints. | |
70b88761 RP |
2791 | |
2792 | For example, the following session excerpt shows an attempt to set a | |
e251e767 | 2793 | breakpoint at the overloaded symbol @code{String::after}. |
70b88761 RP |
2794 | We choose three particular definitions of that function name: |
2795 | ||
6f3ec223 | 2796 | @c FIXME! This is likely to change to show arg type lists, at least |
d55320a0 | 2797 | @smallexample |
18fae2a8 | 2798 | (@value{GDBP}) b String::after |
70b88761 RP |
2799 | [0] cancel |
2800 | [1] all | |
2801 | [2] file:String.cc; line number:867 | |
2802 | [3] file:String.cc; line number:860 | |
2803 | [4] file:String.cc; line number:875 | |
2804 | [5] file:String.cc; line number:853 | |
2805 | [6] file:String.cc; line number:846 | |
2806 | [7] file:String.cc; line number:735 | |
2807 | > 2 4 6 | |
2808 | Breakpoint 1 at 0xb26c: file String.cc, line 867. | |
2809 | Breakpoint 2 at 0xb344: file String.cc, line 875. | |
2810 | Breakpoint 3 at 0xafcc: file String.cc, line 846. | |
2811 | Multiple breakpoints were set. | |
d55320a0 RP |
2812 | Use the "delete" command to delete unwanted |
2813 | breakpoints. | |
18fae2a8 | 2814 | (@value{GDBP}) |
d55320a0 | 2815 | @end smallexample |
1d7c3357 | 2816 | @end ifclear |
70b88761 | 2817 | |
af215b1a VM |
2818 | @c @ifclear BARETARGET |
2819 | @c @node Error in Breakpoints | |
2820 | @c @subsection ``Cannot insert breakpoints'' | |
2821 | @c | |
2822 | @c FIXME!! 14/6/95 Is there a real example of this? Let's use it. | |
2823 | @c | |
2824 | @c Under some operating systems, breakpoints cannot be used in a program if | |
2825 | @c any other process is running that program. In this situation, | |
2826 | @c attempting to run or continue a program with a breakpoint causes | |
2827 | @c @value{GDBN} to stop the other process. | |
2828 | @c | |
2829 | @c When this happens, you have three ways to proceed: | |
2830 | @c | |
2831 | @c @enumerate | |
2832 | @c @item | |
2833 | @c Remove or disable the breakpoints, then continue. | |
2834 | @c | |
2835 | @c @item | |
2836 | @c Suspend @value{GDBN}, and copy the file containing your program to a new | |
2837 | @c name. Resume @value{GDBN} and use the @code{exec-file} command to specify | |
2838 | @c that @value{GDBN} should run your program under that name. | |
2839 | @c Then start your program again. | |
2840 | @c | |
2841 | @c @item | |
2842 | @c Relink your program so that the text segment is nonsharable, using the | |
2843 | @c linker option @samp{-N}. The operating system limitation may not apply | |
2844 | @c to nonsharable executables. | |
2845 | @c @end enumerate | |
2846 | @c @end ifclear | |
70b88761 | 2847 | |
4eb4cf57 | 2848 | @node Continuing and Stepping |
93928b60 | 2849 | @section Continuing and stepping |
70b88761 RP |
2850 | |
2851 | @cindex stepping | |
7463aadd RP |
2852 | @cindex continuing |
2853 | @cindex resuming execution | |
3d3ab540 | 2854 | @dfn{Continuing} means resuming program execution until your program |
cedaf8bc RP |
2855 | completes normally. In contrast, @dfn{stepping} means executing just |
2856 | one more ``step'' of your program, where ``step'' may mean either one | |
2857 | line of source code, or one machine instruction (depending on what | |
2858 | particular command you use). Either when continuing | |
4eb4cf57 | 2859 | or when stepping, your program may stop even sooner, due to |
18fae2a8 | 2860 | @ifset BARETARGET |
4eb4cf57 | 2861 | a breakpoint. |
18fae2a8 RP |
2862 | @end ifset |
2863 | @ifclear BARETARGET | |
6b51acad | 2864 | a breakpoint or a signal. (If due to a signal, you may want to use |
4eb4cf57 RP |
2865 | @code{handle}, or use @samp{signal 0} to resume execution. |
2866 | @xref{Signals, ,Signals}.) | |
18fae2a8 | 2867 | @end ifclear |
3d3ab540 RP |
2868 | |
2869 | @table @code | |
3d3ab540 | 2870 | @kindex continue |
d55320a0 RP |
2871 | @kindex c |
2872 | @kindex fg | |
af215b1a VM |
2873 | @item continue @r{[}@var{ignore-count}@r{]} |
2874 | @itemx c @r{[}@var{ignore-count}@r{]} | |
2875 | @itemx fg @r{[}@var{ignore-count}@r{]} | |
6b51acad RP |
2876 | Resume program execution, at the address where your program last stopped; |
2877 | any breakpoints set at that address are bypassed. The optional argument | |
2878 | @var{ignore-count} allows you to specify a further number of times to | |
2879 | ignore a breakpoint at this location; its effect is like that of | |
2880 | @code{ignore} (@pxref{Conditions, ,Break conditions}). | |
2881 | ||
2882 | The argument @var{ignore-count} is meaningful only when your program | |
d55320a0 RP |
2883 | stopped due to a breakpoint. At other times, the argument to |
2884 | @code{continue} is ignored. | |
2885 | ||
2886 | The synonyms @code{c} and @code{fg} are provided purely for convenience, | |
2887 | and have exactly the same behavior as @code{continue}. | |
2888 | @end table | |
2889 | ||
3d3ab540 | 2890 | To resume execution at a different place, you can use @code{return} |
93928b60 | 2891 | (@pxref{Returning, ,Returning from a function}) to go back to the |
29a2b744 | 2892 | calling function; or @code{jump} (@pxref{Jumping, ,Continuing at a |
93928b60 | 2893 | different address}) to go to an arbitrary location in your program. |
7463aadd RP |
2894 | |
2895 | A typical technique for using stepping is to set a breakpoint | |
93928b60 RP |
2896 | @ifclear CONLY |
2897 | (@pxref{Breakpoints, ,Breakpoints; watchpoints; and exceptions}) | |
2898 | @end ifclear | |
2899 | @ifset CONLY | |
2900 | (@pxref{Breakpoints, ,Breakpoints and watchpoints}) | |
2901 | @end ifset | |
2902 | at the | |
29a2b744 RP |
2903 | beginning of the function or the section of your program where a |
2904 | problem is believed to lie, run your program until it stops at that | |
2905 | breakpoint, and then step through the suspect area, examining the | |
2906 | variables that are interesting, until you see the problem happen. | |
70b88761 RP |
2907 | |
2908 | @table @code | |
70b88761 RP |
2909 | @kindex step |
2910 | @kindex s | |
af215b1a | 2911 | @item step |
29a2b744 | 2912 | Continue running your program until control reaches a different source |
18fae2a8 | 2913 | line, then stop it and return control to @value{GDBN}. This command is |
70b88761 RP |
2914 | abbreviated @code{s}. |
2915 | ||
3d3ab540 | 2916 | @quotation |
068b06f2 JK |
2917 | @c "without debugging information" is imprecise; actually "without line |
2918 | @c numbers in the debugging information". (gcc -g1 has debugging info but | |
2919 | @c not line numbers). But it seems complex to try to make that | |
2920 | @c distinction here. | |
3d3ab540 RP |
2921 | @emph{Warning:} If you use the @code{step} command while control is |
2922 | within a function that was compiled without debugging information, | |
d55320a0 | 2923 | execution proceeds until control reaches a function that does have |
068b06f2 JK |
2924 | debugging information. Likewise, it will not step into a function which |
2925 | is compiled without debugging information. To step through functions | |
2926 | without debugging information, use the @code{stepi} command, described | |
2927 | below. | |
3d3ab540 | 2928 | @end quotation |
70b88761 | 2929 | |
af215b1a VM |
2930 | The @code{step} command now only stops at the first instruction of a |
2931 | source line. This prevents the multiple stops that used to occur in | |
2932 | switch statements, for loops, etc. @code{step} continues to stop if a | |
2933 | function that has debugging information is called within the line. | |
2934 | ||
2935 | Also, the @code{step} command now only enters a subroutine if there is line | |
2936 | number information for the subroutine. Otherwise it acts like the | |
2937 | @code{next} command. This avoids problems when using @code{cc -gl} | |
2938 | on MIPS machines. Previously, @code{step} entered subroutines if there | |
2939 | was any debugging information about the routine. | |
2940 | ||
70b88761 RP |
2941 | @item step @var{count} |
2942 | Continue running as in @code{step}, but do so @var{count} times. If a | |
1d7c3357 RP |
2943 | breakpoint is reached, |
2944 | @ifclear BARETARGET | |
2945 | or a signal not related to stepping occurs before @var{count} steps, | |
2946 | @end ifclear | |
2947 | stepping stops right away. | |
70b88761 | 2948 | |
70b88761 RP |
2949 | @kindex next |
2950 | @kindex n | |
af215b1a | 2951 | @item next @r{[}@var{count}@r{]} |
7463aadd | 2952 | Continue to the next source line in the current (innermost) stack frame. |
af215b1a | 2953 | This is similar to @code{step}, but function calls that appear within the line |
7463aadd | 2954 | of code are executed without stopping. Execution stops when control |
af215b1a VM |
2955 | reaches a different line of code at the original stack level that was |
2956 | executing when you gave the @code{next} command. This command is abbreviated | |
7463aadd | 2957 | @code{n}. |
70b88761 | 2958 | |
7463aadd | 2959 | An argument @var{count} is a repeat count, as for @code{step}. |
70b88761 | 2960 | |
70b88761 | 2961 | |
af215b1a VM |
2962 | @c FIX ME!! Do we delete this, or is there a way it fits in with |
2963 | @c the following paragraph? --- Vctoria | |
2964 | @c | |
2965 | @c @code{next} within a function that lacks debugging information acts like | |
2966 | @c @code{step}, but any function calls appearing within the code of the | |
2967 | @c function are executed without stopping. | |
2968 | ||
2969 | The @code{next} command now only stops at the first instruction of a | |
2970 | source line. This prevents the multiple stops that used to occur in | |
2971 | swtch statements, for loops, etc. | |
2972 | ||
70b88761 | 2973 | @kindex finish |
af215b1a | 2974 | @item finish |
7463aadd RP |
2975 | Continue running until just after function in the selected stack frame |
2976 | returns. Print the returned value (if any). | |
70b88761 | 2977 | |
29a2b744 | 2978 | Contrast this with the @code{return} command (@pxref{Returning, |
93928b60 | 2979 | ,Returning from a function}). |
70b88761 | 2980 | |
70b88761 | 2981 | @kindex until |
6b51acad | 2982 | @itemx u |
70b88761 | 2983 | @kindex u |
af215b1a | 2984 | @item until |
70b88761 RP |
2985 | Continue running until a source line past the current line, in the |
2986 | current stack frame, is reached. This command is used to avoid single | |
2987 | stepping through a loop more than once. It is like the @code{next} | |
2988 | command, except that when @code{until} encounters a jump, it | |
2989 | automatically continues execution until the program counter is greater | |
2990 | than the address of the jump. | |
2991 | ||
2992 | This means that when you reach the end of a loop after single stepping | |
9a27b06e RP |
2993 | though it, @code{until} makes your program continue execution until it |
2994 | exits the loop. In contrast, a @code{next} command at the end of a loop | |
2995 | simply steps back to the beginning of the loop, which forces you to step | |
2996 | through the next iteration. | |
70b88761 | 2997 | |
29a2b744 | 2998 | @code{until} always stops your program if it attempts to exit the current |
70b88761 RP |
2999 | stack frame. |
3000 | ||
3001 | @code{until} may produce somewhat counterintuitive results if the order | |
7463aadd | 3002 | of machine code does not match the order of the source lines. For |
70b88761 RP |
3003 | example, in the following excerpt from a debugging session, the @code{f} |
3004 | (@code{frame}) command shows that execution is stopped at line | |
3005 | @code{206}; yet when we use @code{until}, we get to line @code{195}: | |
3006 | ||
3007 | @example | |
18fae2a8 | 3008 | (@value{GDBP}) f |
70b88761 | 3009 | #0 main (argc=4, argv=0xf7fffae8) at m4.c:206 |
b80282d5 | 3010 | 206 expand_input(); |
18fae2a8 | 3011 | (@value{GDBP}) until |
b80282d5 | 3012 | 195 for ( ; argc > 0; NEXTARG) @{ |
70b88761 RP |
3013 | @end example |
3014 | ||
7463aadd RP |
3015 | This happened because, for execution efficiency, the compiler had |
3016 | generated code for the loop closure test at the end, rather than the | |
3017 | start, of the loop---even though the test in a C @code{for}-loop is | |
3018 | written before the body of the loop. The @code{until} command appeared | |
3019 | to step back to the beginning of the loop when it advanced to this | |
3020 | expression; however, it has not really gone to an earlier | |
3021 | statement---not in terms of the actual machine code. | |
70b88761 RP |
3022 | |
3023 | @code{until} with no argument works by means of single | |
3024 | instruction stepping, and hence is slower than @code{until} with an | |
3025 | argument. | |
3026 | ||
3027 | @item until @var{location} | |
6b51acad | 3028 | @itemx u @var{location} |
29a2b744 RP |
3029 | Continue running your program until either the specified location is |
3030 | reached, or the current stack frame returns. @var{location} is any of | |
3031 | the forms of argument acceptable to @code{break} (@pxref{Set Breaks, | |
93928b60 | 3032 | ,Setting breakpoints}). This form of the command uses breakpoints, |
1041a570 | 3033 | and hence is quicker than @code{until} without an argument. |
70b88761 | 3034 | |
70b88761 RP |
3035 | @kindex stepi |
3036 | @kindex si | |
af215b1a VM |
3037 | @item stepi |
3038 | @itemx si | |
70b88761 RP |
3039 | Execute one machine instruction, then stop and return to the debugger. |
3040 | ||
3041 | It is often useful to do @samp{display/i $pc} when stepping by machine | |
9a27b06e RP |
3042 | instructions. This makes @value{GDBN} automatically display the next |
3043 | instruction to be executed, each time your program stops. @xref{Auto | |
3044 | Display,, Automatic display}. | |
70b88761 RP |
3045 | |
3046 | An argument is a repeat count, as in @code{step}. | |
3047 | ||
ed447b95 | 3048 | @need 750 |
70b88761 RP |
3049 | @kindex nexti |
3050 | @kindex ni | |
af215b1a VM |
3051 | @item nexti |
3052 | @itemx ni | |
70b88761 RP |
3053 | Execute one machine instruction, but if it is a function call, |
3054 | proceed until the function returns. | |
3055 | ||
3056 | An argument is a repeat count, as in @code{next}. | |
70b88761 RP |
3057 | @end table |
3058 | ||
18fae2a8 | 3059 | @ifset POSIX |
4eb4cf57 | 3060 | @node Signals |
70b88761 RP |
3061 | @section Signals |
3062 | @cindex signals | |
3063 | ||
3064 | A signal is an asynchronous event that can happen in a program. The | |
3065 | operating system defines the possible kinds of signals, and gives each | |
3066 | kind a name and a number. For example, in Unix @code{SIGINT} is the | |
3067 | signal a program gets when you type an interrupt (often @kbd{C-c}); | |
3068 | @code{SIGSEGV} is the signal a program gets from referencing a place in | |
3069 | memory far away from all the areas in use; @code{SIGALRM} occurs when | |
29a2b744 | 3070 | the alarm clock timer goes off (which happens only if your program has |
70b88761 RP |
3071 | requested an alarm). |
3072 | ||
3073 | @cindex fatal signals | |
3074 | Some signals, including @code{SIGALRM}, are a normal part of the | |
29a2b744 RP |
3075 | functioning of your program. Others, such as @code{SIGSEGV}, indicate |
3076 | errors; these signals are @dfn{fatal} (kill your program immediately) if the | |
70b88761 | 3077 | program has not specified in advance some other way to handle the signal. |
29a2b744 | 3078 | @code{SIGINT} does not indicate an error in your program, but it is normally |
70b88761 RP |
3079 | fatal so it can carry out the purpose of the interrupt: to kill the program. |
3080 | ||
18fae2a8 RP |
3081 | @value{GDBN} has the ability to detect any occurrence of a signal in your |
3082 | program. You can tell @value{GDBN} in advance what to do for each kind of | |
29a2b744 | 3083 | signal. |
70b88761 RP |
3084 | |
3085 | @cindex handling signals | |
18fae2a8 | 3086 | Normally, @value{GDBN} is set up to ignore non-erroneous signals like @code{SIGALRM} |
29a2b744 RP |
3087 | (so as not to interfere with their role in the functioning of your program) |
3088 | but to stop your program immediately whenever an error signal happens. | |
70b88761 RP |
3089 | You can change these settings with the @code{handle} command. |
3090 | ||
3091 | @table @code | |
70b88761 | 3092 | @kindex info signals |
af215b1a | 3093 | @item info signals |
18fae2a8 | 3094 | Print a table of all the kinds of signals and how @value{GDBN} has been told to |
70b88761 RP |
3095 | handle each one. You can use this to see the signal numbers of all |
3096 | the defined types of signals. | |
3097 | ||
af215b1a VM |
3098 | @code{info handle} is the new alias for @code{info signals}. |
3099 | ||
70b88761 | 3100 | @kindex handle |
af215b1a VM |
3101 | @item handle @var{signal} @var{keywords}@dots{} |
3102 | Change the way @value{GDBN} handles signal @var{signal}. @var{signal} can | |
3103 | be the number of a signal or its name (with or without the @samp{SIG} at the | |
70b88761 RP |
3104 | beginning). The @var{keywords} say what change to make. |
3105 | @end table | |
3106 | ||
3107 | @c @group | |
3108 | The keywords allowed by the @code{handle} command can be abbreviated. | |
3109 | Their full names are: | |
3110 | ||
3111 | @table @code | |
3112 | @item nostop | |
18fae2a8 | 3113 | @value{GDBN} should not stop your program when this signal happens. It may |
70b88761 RP |
3114 | still print a message telling you that the signal has come in. |
3115 | ||
3116 | @item stop | |
18fae2a8 | 3117 | @value{GDBN} should stop your program when this signal happens. This implies |
70b88761 RP |
3118 | the @code{print} keyword as well. |
3119 | ||
3120 | @item print | |
18fae2a8 | 3121 | @value{GDBN} should print a message when this signal happens. |
70b88761 RP |
3122 | |
3123 | @item noprint | |
18fae2a8 | 3124 | @value{GDBN} should not mention the occurrence of the signal at all. This |
70b88761 RP |
3125 | implies the @code{nostop} keyword as well. |
3126 | ||
3127 | @item pass | |
9a27b06e RP |
3128 | @value{GDBN} should allow your program to see this signal; your program |
3129 | can handle the signal, or else it may terminate if the signal is fatal | |
70b88761 RP |
3130 | and not handled. |
3131 | ||
3132 | @item nopass | |
18fae2a8 | 3133 | @value{GDBN} should not allow your program to see this signal. |
70b88761 RP |
3134 | @end table |
3135 | @c @end group | |
3136 | ||
ed447b95 | 3137 | When a signal stops your program, the signal is not visible until you |
9a27b06e | 3138 | continue. Your program sees the signal then, if @code{pass} is in |
ed447b95 RP |
3139 | effect for the signal in question @emph{at that time}. In other words, |
3140 | after @value{GDBN} reports a signal, you can use the @code{handle} | |
9a27b06e RP |
3141 | command with @code{pass} or @code{nopass} to control whether your |
3142 | program sees that signal when you continue. | |
70b88761 | 3143 | |
29a2b744 | 3144 | You can also use the @code{signal} command to prevent your program from |
70b88761 | 3145 | seeing a signal, or cause it to see a signal it normally would not see, |
29a2b744 | 3146 | or to give it any signal at any time. For example, if your program stopped |
7463aadd RP |
3147 | due to some sort of memory reference error, you might store correct |
3148 | values into the erroneous variables and continue, hoping to see more | |
29a2b744 RP |
3149 | execution; but your program would probably terminate immediately as |
3150 | a result of the fatal signal once it saw the signal. To prevent this, | |
3151 | you can continue with @samp{signal 0}. @xref{Signaling, ,Giving your | |
93928b60 | 3152 | program a signal}. |
18fae2a8 | 3153 | @end ifset |
70b88761 | 3154 | |
0cb95a9c RP |
3155 | @ifclear BARETARGET |
3156 | @node Thread Stops | |
3157 | @section Stopping and starting multi-thread programs | |
3158 | ||
3159 | When your program has multiple threads (@pxref{Threads,, Debugging | |
3160 | programs with multiple threads}), you can choose whether to set | |
3161 | breakpoints on all threads, or on a particular thread. | |
3162 | ||
3163 | @table @code | |
22b5dba5 RP |
3164 | @cindex breakpoints and threads |
3165 | @cindex thread breakpoints | |
0cb95a9c RP |
3166 | @kindex break @dots{} thread @var{threadno} |
3167 | @item break @var{linespec} thread @var{threadno} | |
3168 | @itemx break @var{linespec} thread @var{threadno} if @dots{} | |
af215b1a VM |
3169 | @var{linespec} specifies source lines; there are several ways of |
3170 | writing them, but the effect is always to specify some source line. | |
3171 | ||
0cb95a9c RP |
3172 | Use the qualifier @samp{thread @var{threadno}} with a breakpoint command |
3173 | to specify that you only want @value{GDBN} to stop the program when a | |
22b5dba5 RP |
3174 | particular thread reaches this breakpoint. @var{threadno} is one of the |
3175 | numeric thread identifiers assigned by @value{GDBN}, shown in the first | |
3176 | column of the @samp{info threads} display. | |
0cb95a9c RP |
3177 | |
3178 | If you do not specify @samp{thread @var{threadno}} when you set a | |
3179 | breakpoint, the breakpoint applies to @emph{all} threads of your | |
3180 | program. | |
22b5dba5 RP |
3181 | |
3182 | You can use the @code{thread} qualifier on conditional breakpoints as | |
3183 | well; in this case, place @samp{thread @var{threadno}} before the | |
3184 | breakpoint condition, like this: | |
3185 | ||
3186 | @smallexample | |
3187 | (gdb) break frik.c:13 thread 28 if bartab > lim | |
3188 | @end smallexample | |
af215b1a | 3189 | |
0cb95a9c RP |
3190 | @end table |
3191 | ||
3192 | @cindex stopped threads | |
3193 | @cindex threads, stopped | |
3194 | Whenever your program stops under @value{GDBN} for any reason, | |
3195 | @emph{all} threads of execution stop, not just the current thread. This | |
3196 | allows you to examine the overall state of the program, including | |
3197 | switching between threads, without worrying that things may change | |
3198 | underfoot. | |
3199 | ||
3200 | @cindex continuing threads | |
3201 | @cindex threads, continuing | |
3202 | Conversely, whenever you restart the program, @emph{all} threads start | |
3203 | executing. @emph{This is true even when single-stepping} with commands | |
3204 | like @code{step} or @code{next}. | |
3205 | ||
3206 | In particular, @value{GDBN} cannot single-step all threads in lockstep. | |
22b5dba5 RP |
3207 | Since thread scheduling is up to your debugging target's operating |
3208 | system (not controlled by @value{GDBN}), other threads may | |
3209 | execute more than one statement while the current thread completes a | |
3210 | single step. Moreover, in general other threads stop in the middle of a | |
3211 | statement, rather than at a clean statement boundary, when the program | |
3212 | stops. | |
0cb95a9c RP |
3213 | |
3214 | You might even find your program stopped in another thread after | |
3215 | continuing or even single-stepping. This happens whenever some other | |
3216 | thread runs into a breakpoint, a signal, or an exception before the | |
3217 | first thread completes whatever you requested. | |
3218 | @end ifclear | |
3219 | ||
4eb4cf57 | 3220 | @node Stack |
70b88761 RP |
3221 | @chapter Examining the Stack |
3222 | ||
3223 | When your program has stopped, the first thing you need to know is where it | |
3224 | stopped and how it got there. | |
3225 | ||
3226 | @cindex call stack | |
af215b1a VM |
3227 | Each time your program performs a function call, information about the call |
3228 | is generated. | |
3229 | That information includes the location of the call in your program, | |
3230 | the arguments of the call, | |
3231 | and the local variables of the function being called. | |
3232 | The information is saved in a block of data called a @dfn{stack frame}. | |
3233 | The stack frames are allocated in a region of memory called the @dfn{call | |
70b88761 RP |
3234 | stack}. |
3235 | ||
93928b60 RP |
3236 | When your program stops, the @value{GDBN} commands for examining the |
3237 | stack allow you to see all of this information. | |
70b88761 RP |
3238 | |
3239 | @cindex selected frame | |
93928b60 RP |
3240 | One of the stack frames is @dfn{selected} by @value{GDBN} and many |
3241 | @value{GDBN} commands refer implicitly to the selected frame. In | |
3242 | particular, whenever you ask @value{GDBN} for the value of a variable in | |
3243 | your program, the value is found in the selected frame. There are | |
3244 | special @value{GDBN} commands to select whichever frame you are | |
af215b1a | 3245 | interested in. @xref{Selection, ,Selecting a frame}. |
70b88761 | 3246 | |
93928b60 | 3247 | When your program stops, @value{GDBN} automatically selects the |
af215b1a VM |
3248 | currently executing frame and describes it briefly, similar to the |
3249 | @code{frame} command (@pxref{Frame Info, ,Information about a frame}). | |
70b88761 RP |
3250 | |
3251 | @menu | |
ed447b95 | 3252 | * Frames:: Stack frames |
b80282d5 | 3253 | * Backtrace:: Backtraces |
ed447b95 RP |
3254 | * Selection:: Selecting a frame |
3255 | * Frame Info:: Information on a frame | |
572867a8 RP |
3256 | @ifset MIPS |
3257 | * MIPS Stack:: MIPS machines and the function stack | |
3258 | @end ifset | |
70b88761 RP |
3259 | @end menu |
3260 | ||
4eb4cf57 | 3261 | @node Frames |
93928b60 | 3262 | @section Stack frames |
70b88761 RP |
3263 | |
3264 | @cindex frame | |
3265 | @cindex stack frame | |
3266 | The call stack is divided up into contiguous pieces called @dfn{stack | |
3267 | frames}, or @dfn{frames} for short; each frame is the data associated | |
3268 | with one call to one function. The frame contains the arguments given | |
3269 | to the function, the function's local variables, and the address at | |
3270 | which the function is executing. | |
3271 | ||
3272 | @cindex initial frame | |
3273 | @cindex outermost frame | |
3274 | @cindex innermost frame | |
3275 | When your program is started, the stack has only one frame, that of the | |
3276 | function @code{main}. This is called the @dfn{initial} frame or the | |
3277 | @dfn{outermost} frame. Each time a function is called, a new frame is | |
3278 | made. Each time a function returns, the frame for that function invocation | |
3279 | is eliminated. If a function is recursive, there can be many frames for | |
3280 | the same function. The frame for the function in which execution is | |
3281 | actually occurring is called the @dfn{innermost} frame. This is the most | |
3282 | recently created of all the stack frames that still exist. | |
3283 | ||
3284 | @cindex frame pointer | |
3285 | Inside your program, stack frames are identified by their addresses. A | |
3286 | stack frame consists of many bytes, each of which has its own address; each | |
af215b1a | 3287 | kind of computer has a convention for choosing one byte whose |
70b88761 RP |
3288 | address serves as the address of the frame. Usually this address is kept |
3289 | in a register called the @dfn{frame pointer register} while execution is | |
3290 | going on in that frame. | |
3291 | ||
3292 | @cindex frame number | |
18fae2a8 | 3293 | @value{GDBN} assigns numbers to all existing stack frames, starting with |
70b88761 RP |
3294 | zero for the innermost frame, one for the frame that called it, |
3295 | and so on upward. These numbers do not really exist in your program; | |
18fae2a8 RP |
3296 | they are assigned by @value{GDBN} to give you a way of designating stack |
3297 | frames in @value{GDBN} commands. | |
70b88761 | 3298 | |
6b51acad | 3299 | @c below produces an acceptable overful hbox. --mew 13aug1993 |
70b88761 | 3300 | @cindex frameless execution |
8c69096b | 3301 | Some compilers provide a way to compile functions so that they operate |
18fae2a8 | 3302 | without stack frames. (For example, the @code{@value{GCC}} option |
9a27b06e | 3303 | @samp{-fomit-frame-pointer} generates functions without a frame.) |
70b88761 | 3304 | This is occasionally done with heavily used library functions to save |
8c69096b RP |
3305 | the frame setup time. @value{GDBN} has limited facilities for dealing |
3306 | with these function invocations. If the innermost function invocation | |
9a27b06e | 3307 | has no stack frame, @value{GDBN} nevertheless regards it as though |
8c69096b RP |
3308 | it had a separate frame, which is numbered zero as usual, allowing |
3309 | correct tracing of the function call chain. However, @value{GDBN} has | |
3310 | no provision for frameless functions elsewhere in the stack. | |
70b88761 | 3311 | |
af215b1a VM |
3312 | @table @code |
3313 | @kindex frame | |
3314 | @item frame @var{args} | |
3315 | The @code{frame} command allows you to move from one stack frame to another, | |
3316 | and to print the stack frame you select. @var{args} may be either the | |
271fef25 | 3317 | address of the frame or the stack frame number. Without an argument, |
af215b1a VM |
3318 | @code{frame} prints the current stack frame. |
3319 | ||
3320 | @kindex select-frame | |
3321 | @item select-frame | |
3322 | The @code{select-frame} command allows you to move from one stack frame | |
3323 | to another without printing the frame. This is the silent version of | |
3324 | @code{frame}. | |
3325 | @end table | |
3326 | ||
4eb4cf57 | 3327 | @node Backtrace |
70b88761 RP |
3328 | @section Backtraces |
3329 | ||
29a2b744 | 3330 | A backtrace is a summary of how your program got where it is. It shows one |
70b88761 RP |
3331 | line per frame, for many frames, starting with the currently executing |
3332 | frame (frame zero), followed by its caller (frame one), and on up the | |
3333 | stack. | |
3334 | ||
3335 | @table @code | |
70b88761 RP |
3336 | @kindex backtrace |
3337 | @kindex bt | |
af215b1a VM |
3338 | @item backtrace |
3339 | @itemx bt | |
70b88761 RP |
3340 | Print a backtrace of the entire stack: one line per frame for all |
3341 | frames in the stack. | |
3342 | ||
3343 | You can stop the backtrace at any time by typing the system interrupt | |
3344 | character, normally @kbd{C-c}. | |
3345 | ||
3346 | @item backtrace @var{n} | |
3347 | @itemx bt @var{n} | |
3348 | Similar, but print only the innermost @var{n} frames. | |
3349 | ||
3350 | @item backtrace -@var{n} | |
3351 | @itemx bt -@var{n} | |
3352 | Similar, but print only the outermost @var{n} frames. | |
3353 | @end table | |
3354 | ||
3355 | @kindex where | |
3356 | @kindex info stack | |
3357 | @kindex info s | |
3358 | The names @code{where} and @code{info stack} (abbreviated @code{info s}) | |
3359 | are additional aliases for @code{backtrace}. | |
3360 | ||
3361 | Each line in the backtrace shows the frame number and the function name. | |
3362 | The program counter value is also shown---unless you use @code{set | |
3363 | print address off}. The backtrace also shows the source file name and | |
3364 | line number, as well as the arguments to the function. The program | |
3365 | counter value is omitted if it is at the beginning of the code for that | |
3366 | line number. | |
3367 | ||
3368 | Here is an example of a backtrace. It was made with the command | |
3369 | @samp{bt 3}, so it shows the innermost three frames. | |
3370 | ||
3371 | @smallexample | |
3372 | @group | |
203eea5d RP |
3373 | #0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8) |
3374 | at builtin.c:993 | |
70b88761 RP |
3375 | #1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242 |
3376 | #2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08) | |
3377 | at macro.c:71 | |
3378 | (More stack frames follow...) | |
3379 | @end group | |
3380 | @end smallexample | |
3381 | ||
3382 | @noindent | |
29a2b744 RP |
3383 | The display for frame zero does not begin with a program counter |
3384 | value, indicating that your program has stopped at the beginning of the | |
70b88761 RP |
3385 | code for line @code{993} of @code{builtin.c}. |
3386 | ||
4eb4cf57 | 3387 | @node Selection |
93928b60 | 3388 | @section Selecting a frame |
70b88761 | 3389 | |
29a2b744 | 3390 | Most commands for examining the stack and other data in your program work on |
70b88761 RP |
3391 | whichever stack frame is selected at the moment. Here are the commands for |
3392 | selecting a stack frame; all of them finish by printing a brief description | |
3393 | of the stack frame just selected. | |
3394 | ||
3395 | @table @code | |
70b88761 RP |
3396 | @kindex frame |
3397 | @kindex f | |
af215b1a VM |
3398 | @item frame @var{n} |
3399 | @itemx f @var{n} | |
70b88761 RP |
3400 | Select frame number @var{n}. Recall that frame zero is the innermost |
3401 | (currently executing) frame, frame one is the frame that called the | |
93918348 RP |
3402 | innermost one, and so on. The highest-numbered frame is the one for |
3403 | @code{main}. | |
70b88761 RP |
3404 | |
3405 | @item frame @var{addr} | |
3406 | @itemx f @var{addr} | |
3407 | Select the frame at address @var{addr}. This is useful mainly if the | |
3408 | chaining of stack frames has been damaged by a bug, making it | |
18fae2a8 | 3409 | impossible for @value{GDBN} to assign numbers properly to all frames. In |
29a2b744 | 3410 | addition, this can be useful when your program has multiple stacks and |
70b88761 RP |
3411 | switches between them. |
3412 | ||
7e17041f | 3413 | @ifclear H8EXCLUSIVE |
70b88761 | 3414 | On the SPARC architecture, @code{frame} needs two addresses to |
e251e767 | 3415 | select an arbitrary frame: a frame pointer and a stack pointer. |
7e17041f JK |
3416 | |
3417 | On the MIPS and Alpha architecture, it needs two addresses: a stack | |
3418 | pointer and a program counter. | |
3419 | ||
3420 | On the 29k architecture, it needs three addresses: a register stack | |
3421 | pointer, a program counter, and a memory stack pointer. | |
70b88761 | 3422 | @c note to future updaters: this is conditioned on a flag |
7e17041f JK |
3423 | @c SETUP_ARBITRARY_FRAME in the tm-*.h files. The above is up to date |
3424 | @c as of 27 Jan 1994. | |
3425 | @end ifclear | |
70b88761 | 3426 | |
70b88761 | 3427 | @kindex up |
af215b1a | 3428 | @item up @var{n} |
70b88761 RP |
3429 | Move @var{n} frames up the stack. For positive numbers @var{n}, this |
3430 | advances toward the outermost frame, to higher frame numbers, to frames | |
3431 | that have existed longer. @var{n} defaults to one. | |
3432 | ||
70b88761 RP |
3433 | @kindex down |
3434 | @kindex do | |
af215b1a | 3435 | @item down @var{n} |
70b88761 RP |
3436 | Move @var{n} frames down the stack. For positive numbers @var{n}, this |
3437 | advances toward the innermost frame, to lower frame numbers, to frames | |
3438 | that were created more recently. @var{n} defaults to one. You may | |
3439 | abbreviate @code{down} as @code{do}. | |
3440 | @end table | |
3441 | ||
3442 | All of these commands end by printing two lines of output describing the | |
3443 | frame. The first line shows the frame number, the function name, the | |
3444 | arguments, and the source file and line number of execution in that | |
ed447b95 | 3445 | frame. The second line shows the text of that source line. |
70b88761 | 3446 | |
b1955f0b | 3447 | @need 1000 |
ed447b95 | 3448 | For example: |
b1955f0b | 3449 | |
70b88761 | 3450 | @smallexample |
29a2b744 | 3451 | @group |
18fae2a8 | 3452 | (@value{GDBP}) up |
203eea5d RP |
3453 | #1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc) |
3454 | at env.c:10 | |
70b88761 | 3455 | 10 read_input_file (argv[i]); |
29a2b744 | 3456 | @end group |
70b88761 RP |
3457 | @end smallexample |
3458 | ||
9a27b06e RP |
3459 | After such a printout, the @code{list} command with no arguments |
3460 | prints ten lines centered on the point of execution in the frame. | |
93928b60 | 3461 | @xref{List, ,Printing source lines}. |
70b88761 RP |
3462 | |
3463 | @table @code | |
70b88761 RP |
3464 | @kindex down-silently |
3465 | @kindex up-silently | |
af215b1a VM |
3466 | @item up-silently @var{n} |
3467 | @itemx down-silently @var{n} | |
70b88761 RP |
3468 | These two commands are variants of @code{up} and @code{down}, |
3469 | respectively; they differ in that they do their work silently, without | |
3470 | causing display of the new frame. They are intended primarily for use | |
18fae2a8 | 3471 | in @value{GDBN} command scripts, where the output might be unnecessary and |
e251e767 | 3472 | distracting. |
70b88761 RP |
3473 | @end table |
3474 | ||
4eb4cf57 | 3475 | @node Frame Info |
93928b60 | 3476 | @section Information about a frame |
70b88761 RP |
3477 | |
3478 | There are several other commands to print information about the selected | |
3479 | stack frame. | |
3480 | ||
3481 | @table @code | |
3482 | @item frame | |
3483 | @itemx f | |
29a2b744 RP |
3484 | When used without any argument, this command does not change which |
3485 | frame is selected, but prints a brief description of the currently | |
70b88761 | 3486 | selected stack frame. It can be abbreviated @code{f}. With an |
ed447b95 | 3487 | argument, this command is used to select a stack frame. |
93928b60 | 3488 | @xref{Selection, ,Selecting a frame}. |
70b88761 | 3489 | |
29a2b744 | 3490 | @kindex info frame |
70b88761 | 3491 | @kindex info f |
af215b1a VM |
3492 | @item info frame |
3493 | @itemx info f | |
70b88761 | 3494 | This command prints a verbose description of the selected stack frame, |
af215b1a VM |
3495 | including: |
3496 | ||
d056cc31 | 3497 | @itemize @bullet |
af215b1a VM |
3498 | @item |
3499 | the address of the frame | |
3500 | @item | |
3501 | the address of the next frame down (called by this frame) | |
3502 | @item | |
3503 | the address of the next frame up (caller of this frame) | |
3504 | @item | |
3505 | the language in which the source code corresponding to this frame is written | |
3506 | @item | |
3507 | the address of the frame's arguments | |
3508 | @item | |
3509 | the program counter saved in it (the address of execution in the caller frame) | |
3510 | @item | |
3511 | which registers were saved in the frame | |
3512 | @end itemize | |
3513 | ||
3514 | @noindent The verbose description is useful when | |
70b88761 RP |
3515 | something has gone wrong that has made the stack format fail to fit |
3516 | the usual conventions. | |
3517 | ||
3518 | @item info frame @var{addr} | |
3519 | @itemx info f @var{addr} | |
7e17041f JK |
3520 | Print a verbose description of the frame at address @var{addr}, without |
3521 | selecting that frame. The selected frame remains unchanged by this | |
3522 | command. This requires the same kind of address (more than one for some | |
3523 | architectures) that you specify in the @code{frame} command. | |
3524 | @xref{Selection, ,Selecting a frame}. | |
70b88761 | 3525 | |
70b88761 | 3526 | @kindex info args |
af215b1a | 3527 | @item info args |
70b88761 RP |
3528 | Print the arguments of the selected frame, each on a separate line. |
3529 | ||
3530 | @item info locals | |
3531 | @kindex info locals | |
3532 | Print the local variables of the selected frame, each on a separate | |
ed447b95 RP |
3533 | line. These are all variables (declared either static or automatic) |
3534 | accessible at the point of execution of the selected frame. | |
70b88761 | 3535 | |
1d7c3357 | 3536 | @ifclear CONLY |
70b88761 RP |
3537 | @kindex info catch |
3538 | @cindex catch exceptions | |
3539 | @cindex exception handlers | |
af215b1a | 3540 | @item info catch |
70b88761 RP |
3541 | Print a list of all the exception handlers that are active in the |
3542 | current stack frame at the current point of execution. To see other | |
3543 | exception handlers, visit the associated frame (using the @code{up}, | |
3544 | @code{down}, or @code{frame} commands); then type @code{info catch}. | |
93928b60 | 3545 | @xref{Exception Handling, ,Breakpoints and exceptions}. |
1d7c3357 | 3546 | @end ifclear |
70b88761 RP |
3547 | @end table |
3548 | ||
572867a8 RP |
3549 | @ifset MIPS |
3550 | @node MIPS Stack | |
3551 | @section MIPS machines and the function stack | |
3552 | ||
3553 | @cindex stack on MIPS | |
3554 | @cindex MIPS stack | |
3555 | MIPS based computers use an unusual stack frame, which sometimes | |
3556 | requires @value{GDBN} to search backward in the object code to find the | |
3557 | beginning of a function. | |
3558 | ||
3559 | @cindex response time, MIPS debugging | |
3560 | To improve response time (especially for embedded applications, where | |
3561 | @value{GDBN} may be restricted to a slow serial line for this search) | |
3562 | you may want to limit the size of this search, using one of these | |
3563 | commands: | |
572867a8 | 3564 | |
572867a8 | 3565 | @table @code |
af215b1a | 3566 | @cindex @code{heuristic-fence-post} (MIPS) |
572867a8 | 3567 | @item set heuristic-fence-post @var{limit} |
c79890ee | 3568 | Restrict @value{GDBN} to examining at most @var{limit} bytes in its search |
af215b1a VM |
3569 | for the beginning of a function. A value of @var{0} (the default) |
3570 | means there is no limit. However, except for @var{0}, the larger the | |
3571 | limit the more bytes @code{heuristic-fence-post} must search and | |
3572 | therefore the longer it takes to run. | |
572867a8 RP |
3573 | |
3574 | @item show heuristic-fence-post | |
3575 | Display the current limit. | |
3576 | @end table | |
3577 | ||
3578 | @noindent | |
3579 | These commands are available @emph{only} when @value{GDBN} is configured | |
3580 | for debugging programs on MIPS processors. | |
3581 | @end ifset | |
3582 | ||
4eb4cf57 | 3583 | @node Source |
70b88761 RP |
3584 | @chapter Examining Source Files |
3585 | ||
18fae2a8 | 3586 | @value{GDBN} can print parts of your program's source, since the debugging |
ed447b95 | 3587 | information recorded in the program tells @value{GDBN} what source files were |
18fae2a8 | 3588 | used to build it. When your program stops, @value{GDBN} spontaneously prints |
1041a570 | 3589 | the line where it stopped. Likewise, when you select a stack frame |
93928b60 | 3590 | (@pxref{Selection, ,Selecting a frame}), @value{GDBN} prints the line where |
1041a570 RP |
3591 | execution in that frame has stopped. You can print other portions of |
3592 | source files by explicit command. | |
70b88761 | 3593 | |
18fae2a8 | 3594 | @ifclear DOSHOST |
af215b1a VM |
3595 | If you use @value{GDBN} through its @sc{gnu} Emacs interface, you may prefer |
3596 | to use | |
3597 | Emacs facilities to view source; @pxref{Emacs, ,Using @value{GDBN} under @sc{gnu} Emacs}. | |
18fae2a8 | 3598 | @end ifclear |
70b88761 RP |
3599 | |
3600 | @menu | |
ed447b95 | 3601 | * List:: Printing source lines |
18fae2a8 | 3602 | @ifclear DOSHOST |
ed447b95 | 3603 | * Search:: Searching source files |
18fae2a8 | 3604 | @end ifclear |
b0157555 | 3605 | |
ed447b95 RP |
3606 | * Source Path:: Specifying source directories |
3607 | * Machine Code:: Source and machine code | |
70b88761 RP |
3608 | @end menu |
3609 | ||
4eb4cf57 | 3610 | @node List |
93928b60 | 3611 | @section Printing source lines |
70b88761 RP |
3612 | |
3613 | @kindex list | |
3614 | @kindex l | |
3615 | To print lines from a source file, use the @code{list} command | |
af215b1a VM |
3616 | (abbreviated @code{l}). By default, ten lines are printed. |
3617 | There are several ways to specify what part of the file you want to print. | |
70b88761 RP |
3618 | |
3619 | Here are the forms of the @code{list} command most commonly used: | |
3620 | ||
3621 | @table @code | |
3622 | @item list @var{linenum} | |
c338a2fd | 3623 | Print lines centered around line number @var{linenum} in the |
70b88761 RP |
3624 | current source file. |
3625 | ||
3626 | @item list @var{function} | |
c338a2fd | 3627 | Print lines centered around the beginning of function |
70b88761 RP |
3628 | @var{function}. |
3629 | ||
3630 | @item list | |
c338a2fd RP |
3631 | Print more lines. If the last lines printed were printed with a |
3632 | @code{list} command, this prints lines following the last lines | |
70b88761 | 3633 | printed; however, if the last line printed was a solitary line printed |
29a2b744 | 3634 | as part of displaying a stack frame (@pxref{Stack, ,Examining the |
1041a570 | 3635 | Stack}), this prints lines centered around that line. |
70b88761 RP |
3636 | |
3637 | @item list - | |
c338a2fd RP |
3638 | Print lines just before the lines last printed. |
3639 | @end table | |
3640 | ||
18fae2a8 | 3641 | By default, @value{GDBN} prints ten source lines with any of these forms of |
c338a2fd RP |
3642 | the @code{list} command. You can change this using @code{set listsize}: |
3643 | ||
3644 | @table @code | |
c338a2fd | 3645 | @kindex set listsize |
af215b1a | 3646 | @item set listsize @var{count} |
c338a2fd RP |
3647 | Make the @code{list} command display @var{count} source lines (unless |
3648 | the @code{list} argument explicitly specifies some other number). | |
3649 | ||
c338a2fd | 3650 | @kindex show listsize |
af215b1a | 3651 | @item show listsize |
9a27b06e | 3652 | Display the number of lines that @code{list} prints. |
70b88761 RP |
3653 | @end table |
3654 | ||
3655 | Repeating a @code{list} command with @key{RET} discards the argument, | |
3656 | so it is equivalent to typing just @code{list}. This is more useful | |
3657 | than listing the same lines again. An exception is made for an | |
3658 | argument of @samp{-}; that argument is preserved in repetition so that | |
3659 | each repetition moves up in the source file. | |
3660 | ||
3661 | @cindex linespec | |
3662 | In general, the @code{list} command expects you to supply zero, one or two | |
3663 | @dfn{linespecs}. Linespecs specify source lines; there are several ways | |
3664 | of writing them but the effect is always to specify some source line. | |
3665 | Here is a complete description of the possible arguments for @code{list}: | |
3666 | ||
3667 | @table @code | |
3668 | @item list @var{linespec} | |
c338a2fd | 3669 | Print lines centered around the line specified by @var{linespec}. |
70b88761 RP |
3670 | |
3671 | @item list @var{first},@var{last} | |
3672 | Print lines from @var{first} to @var{last}. Both arguments are | |
3673 | linespecs. | |
3674 | ||
3675 | @item list ,@var{last} | |
c338a2fd | 3676 | Print lines ending with @var{last}. |
70b88761 RP |
3677 | |
3678 | @item list @var{first}, | |
c338a2fd | 3679 | Print lines starting with @var{first}. |
70b88761 RP |
3680 | |
3681 | @item list + | |
c338a2fd | 3682 | Print lines just after the lines last printed. |
70b88761 RP |
3683 | |
3684 | @item list - | |
c338a2fd | 3685 | Print lines just before the lines last printed. |
70b88761 RP |
3686 | |
3687 | @item list | |
3688 | As described in the preceding table. | |
3689 | @end table | |
3690 | ||
3691 | Here are the ways of specifying a single source line---all the | |
3692 | kinds of linespec. | |
3693 | ||
3694 | @table @code | |
3695 | @item @var{number} | |
3696 | Specifies line @var{number} of the current source file. | |
3697 | When a @code{list} command has two linespecs, this refers to | |
3698 | the same source file as the first linespec. | |
3699 | ||
3700 | @item +@var{offset} | |
3701 | Specifies the line @var{offset} lines after the last line printed. | |
3702 | When used as the second linespec in a @code{list} command that has | |
3703 | two, this specifies the line @var{offset} lines down from the | |
3704 | first linespec. | |
3705 | ||
3706 | @item -@var{offset} | |
3707 | Specifies the line @var{offset} lines before the last line printed. | |
3708 | ||
3709 | @item @var{filename}:@var{number} | |
3710 | Specifies line @var{number} in the source file @var{filename}. | |
3711 | ||
3712 | @item @var{function} | |
af215b1a VM |
3713 | Specifies the line that begins the body of the function @var{function}. |
3714 | For example: in C, this is the line with the open brace. | |
70b88761 RP |
3715 | |
3716 | @item @var{filename}:@var{function} | |
3717 | Specifies the line of the open-brace that begins the body of the | |
3718 | function @var{function} in the file @var{filename}. You only need the | |
3719 | file name with a function name to avoid ambiguity when there are | |
3720 | identically named functions in different source files. | |
3721 | ||
3722 | @item *@var{address} | |
3723 | Specifies the line containing the program address @var{address}. | |
3724 | @var{address} may be any expression. | |
3725 | @end table | |
3726 | ||
18fae2a8 | 3727 | @ifclear DOSHOST |
4eb4cf57 | 3728 | @node Search |
93928b60 | 3729 | @section Searching source files |
70b88761 RP |
3730 | @cindex searching |
3731 | @kindex reverse-search | |
3732 | ||
3733 | There are two commands for searching through the current source file for a | |
3734 | regular expression. | |
3735 | ||
3736 | @table @code | |
70b88761 RP |
3737 | @kindex search |
3738 | @kindex forward-search | |
af215b1a VM |
3739 | @item forward-search @var{regexp} |
3740 | @itemx search @var{regexp} | |
1041a570 RP |
3741 | The command @samp{forward-search @var{regexp}} checks each line, |
3742 | starting with the one following the last line listed, for a match for | |
af215b1a | 3743 | @var{regexp}. It lists the line that is found. You can use the |
1041a570 RP |
3744 | synonym @samp{search @var{regexp}} or abbreviate the command name as |
3745 | @code{fo}. | |
70b88761 RP |
3746 | |
3747 | @item reverse-search @var{regexp} | |
3748 | The command @samp{reverse-search @var{regexp}} checks each line, starting | |
3749 | with the one before the last line listed and going backward, for a match | |
3750 | for @var{regexp}. It lists the line that is found. You can abbreviate | |
3751 | this command as @code{rev}. | |
3752 | @end table | |
18fae2a8 | 3753 | @end ifclear |
70b88761 | 3754 | |
4eb4cf57 | 3755 | @node Source Path |
93928b60 | 3756 | @section Specifying source directories |
70b88761 RP |
3757 | |
3758 | @cindex source path | |
3759 | @cindex directories for source files | |
3760 | Executable programs sometimes do not record the directories of the source | |
3761 | files from which they were compiled, just the names. Even when they do, | |
3762 | the directories could be moved between the compilation and your debugging | |
18fae2a8 RP |
3763 | session. @value{GDBN} has a list of directories to search for source files; |
3764 | this is called the @dfn{source path}. Each time @value{GDBN} wants a source file, | |
70b88761 RP |
3765 | it tries all the directories in the list, in the order they are present |
3766 | in the list, until it finds a file with the desired name. Note that | |
3767 | the executable search path is @emph{not} used for this purpose. Neither is | |
3768 | the current working directory, unless it happens to be in the source | |
3769 | path. | |
3770 | ||
9a27b06e RP |
3771 | If @value{GDBN} cannot find a source file in the source path, and the |
3772 | object program records a directory, @value{GDBN} tries that directory | |
3773 | too. If the source path is empty, and there is no record of the | |
3774 | compilation directory, @value{GDBN} looks in the current directory as a | |
3775 | last resort. | |
70b88761 | 3776 | |
9a27b06e | 3777 | Whenever you reset or rearrange the source path, @value{GDBN} clears out |
b1955f0b RP |
3778 | any information it has cached about where source files are found and where |
3779 | each line is in the file. | |
70b88761 RP |
3780 | |
3781 | @kindex directory | |
af215b1a | 3782 | @kindex dir |
18fae2a8 | 3783 | When you start @value{GDBN}, its source path is empty. |
70b88761 RP |
3784 | To add other directories, use the @code{directory} command. |
3785 | ||
3786 | @table @code | |
3787 | @item directory @var{dirname} @dots{} | |
af215b1a | 3788 | @item dir @var{dirname} @dots{} |
70b88761 RP |
3789 | Add directory @var{dirname} to the front of the source path. Several |
3790 | directory names may be given to this command, separated by @samp{:} or | |
3791 | whitespace. You may specify a directory that is already in the source | |
9a27b06e | 3792 | path; this moves it forward, so @value{GDBN} searches it sooner. |
7463aadd | 3793 | |
fa6df1a7 RP |
3794 | @kindex cdir |
3795 | @kindex cwd | |
a88ec213 RP |
3796 | @kindex $cdir |
3797 | @kindex $cwd | |
fa6df1a7 RP |
3798 | @cindex compilation directory |
3799 | @cindex current directory | |
3800 | @cindex working directory | |
3801 | @cindex directory, current | |
3802 | @cindex directory, compilation | |
7463aadd RP |
3803 | You can use the string @samp{$cdir} to refer to the compilation |
3804 | directory (if one is recorded), and @samp{$cwd} to refer to the current | |
3805 | working directory. @samp{$cwd} is not the same as @samp{.}---the former | |
18fae2a8 | 3806 | tracks the current working directory as it changes during your @value{GDBN} |
7463aadd RP |
3807 | session, while the latter is immediately expanded to the current |
3808 | directory at the time you add an entry to the source path. | |
70b88761 RP |
3809 | |
3810 | @item directory | |
3811 | Reset the source path to empty again. This requires confirmation. | |
3812 | ||
3813 | @c RET-repeat for @code{directory} is explicitly disabled, but since | |
29a2b744 | 3814 | @c repeating it would be a no-op we do not say that. (thanks to RMS) |
70b88761 RP |
3815 | |
3816 | @item show directories | |
3817 | @kindex show directories | |
3818 | Print the source path: show which directories it contains. | |
3819 | @end table | |
3820 | ||
3821 | If your source path is cluttered with directories that are no longer of | |
18fae2a8 | 3822 | interest, @value{GDBN} may sometimes cause confusion by finding the wrong |
70b88761 RP |
3823 | versions of source. You can correct the situation as follows: |
3824 | ||
3825 | @enumerate | |
3826 | @item | |
3827 | Use @code{directory} with no argument to reset the source path to empty. | |
3828 | ||
3829 | @item | |
3830 | Use @code{directory} with suitable arguments to reinstall the | |
3831 | directories you want in the source path. You can add all the | |
3832 | directories in one command. | |
3833 | @end enumerate | |
3834 | ||
4eb4cf57 | 3835 | @node Machine Code |
93928b60 | 3836 | @section Source and machine code |
1041a570 | 3837 | |
70b88761 | 3838 | You can use the command @code{info line} to map source lines to program |
ed447b95 | 3839 | addresses (and vice versa), and the command @code{disassemble} to display |
af215b1a VM |
3840 | a range of addresses as machine instructions. When run under @sc{gnu} Emacs |
3841 | mode, the @code{info line} command now causes the arrow to point to the | |
3842 | line specified. Also, @code{info line} prints addresses in symbolic form as | |
3843 | well as hex. | |
70b88761 RP |
3844 | |
3845 | @table @code | |
70b88761 | 3846 | @kindex info line |
af215b1a | 3847 | @item info line @var{linespec} |
70b88761 | 3848 | Print the starting and ending addresses of the compiled code for |
1041a570 RP |
3849 | source line @var{linespec}. You can specify source lines in any of |
3850 | the ways understood by the @code{list} command (@pxref{List, ,Printing | |
93928b60 | 3851 | source lines}). |
70b88761 RP |
3852 | @end table |
3853 | ||
1041a570 RP |
3854 | For example, we can use @code{info line} to discover the location of |
3855 | the object code for the first line of function | |
3856 | @code{m4_changequote}: | |
3857 | ||
70b88761 | 3858 | @smallexample |
18fae2a8 | 3859 | (@value{GDBP}) info line m4_changecom |
70b88761 RP |
3860 | Line 895 of "builtin.c" starts at pc 0x634c and ends at 0x6350. |
3861 | @end smallexample | |
3862 | ||
3863 | @noindent | |
3864 | We can also inquire (using @code{*@var{addr}} as the form for | |
3865 | @var{linespec}) what source line covers a particular address: | |
3866 | @smallexample | |
18fae2a8 | 3867 | (@value{GDBP}) info line *0x63ff |
70b88761 RP |
3868 | Line 926 of "builtin.c" starts at pc 0x63e4 and ends at 0x6404. |
3869 | @end smallexample | |
3870 | ||
c338a2fd | 3871 | @cindex @code{$_} and @code{info line} |
29a2b744 RP |
3872 | After @code{info line}, the default address for the @code{x} command |
3873 | is changed to the starting address of the line, so that @samp{x/i} is | |
3874 | sufficient to begin examining the machine code (@pxref{Memory, | |
93928b60 | 3875 | ,Examining memory}). Also, this address is saved as the value of the |
29a2b744 | 3876 | convenience variable @code{$_} (@pxref{Convenience Vars, ,Convenience |
93928b60 | 3877 | variables}). |
70b88761 RP |
3878 | |
3879 | @table @code | |
3880 | @kindex disassemble | |
c5f69ff8 RP |
3881 | @cindex assembly instructions |
3882 | @cindex instructions, assembly | |
3883 | @cindex machine instructions | |
3884 | @cindex listing machine instructions | |
af215b1a | 3885 | @item disassemble |
e94b4a2b RP |
3886 | This specialized command dumps a range of memory as machine |
3887 | instructions. The default memory range is the function surrounding the | |
3888 | program counter of the selected frame. A single argument to this | |
9a27b06e RP |
3889 | command is a program counter value; @value{GDBN} dumps the function |
3890 | surrounding this value. Two arguments specify a range of addresses | |
3891 | (first inclusive, second exclusive) to dump. | |
70b88761 RP |
3892 | @end table |
3893 | ||
a64a6c2b | 3894 | @ifclear H8EXCLUSIVE |
70b88761 | 3895 | We can use @code{disassemble} to inspect the object code |
4eb4cf57 RP |
3896 | range shown in the last @code{info line} example (the example |
3897 | shows SPARC machine instructions): | |
70b88761 | 3898 | |
18fae2a8 | 3899 | |
70b88761 | 3900 | @smallexample |
18fae2a8 | 3901 | (@value{GDBP}) disas 0x63e4 0x6404 |
70b88761 | 3902 | Dump of assembler code from 0x63e4 to 0x6404: |
b80282d5 RP |
3903 | 0x63e4 <builtin_init+5340>: ble 0x63f8 <builtin_init+5360> |
3904 | 0x63e8 <builtin_init+5344>: sethi %hi(0x4c00), %o0 | |
3905 | 0x63ec <builtin_init+5348>: ld [%i1+4], %o0 | |
3906 | 0x63f0 <builtin_init+5352>: b 0x63fc <builtin_init+5364> | |
3907 | 0x63f4 <builtin_init+5356>: ld [%o0+4], %o0 | |
3908 | 0x63f8 <builtin_init+5360>: or %o0, 0x1a4, %o0 | |
3909 | 0x63fc <builtin_init+5364>: call 0x9288 <path_search> | |
e251e767 | 3910 | 0x6400 <builtin_init+5368>: nop |
70b88761 | 3911 | End of assembler dump. |
70b88761 | 3912 | @end smallexample |
18fae2a8 | 3913 | @end ifclear |
4eb4cf57 | 3914 | |
a64a6c2b | 3915 | @ifset H8EXCLUSIVE |
4eb4cf57 RP |
3916 | For example, here is the beginning of the output for the |
3917 | disassembly of a function @code{fact}: | |
70b88761 | 3918 | |
18fae2a8 | 3919 | |
4eb4cf57 | 3920 | @smallexample |
18fae2a8 | 3921 | (@value{GDBP}) disas fact |
4eb4cf57 RP |
3922 | Dump of assembler code for function fact: |
3923 | to 0x808c: | |
3924 | 0x802c <fact>: 6d f2 mov.w r2,@@-r7 | |
3925 | 0x802e <fact+2>: 6d f3 mov.w r3,@@-r7 | |
3926 | 0x8030 <fact+4>: 6d f6 mov.w r6,@@-r7 | |
3927 | 0x8032 <fact+6>: 0d 76 mov.w r7,r6 | |
3928 | 0x8034 <fact+8>: 6f 70 00 08 mov.w @@(0x8,r7),r0 | |
3929 | 0x8038 <fact+12> 19 11 sub.w r1,r1 | |
3930 | . | |
3931 | . | |
3932 | . | |
3933 | @end smallexample | |
18fae2a8 | 3934 | @end ifset |
4eb4cf57 | 3935 | |
892d7e9f SG |
3936 | @table @code |
3937 | @kindex set assembly-language | |
3938 | @cindex assembly instructions | |
3939 | @cindex instructions, assembly | |
3940 | @cindex machine instructions | |
3941 | @cindex listing machine instructions | |
3942 | @item set assembly-language @var{instruction-set} | |
3943 | This command selects the instruction set to use when disassembling the program via the | |
3944 | @code{disassemble} or @code{x/i} commands. It is useful for architectures that | |
3945 | have more than one native instruction set. | |
3946 | ||
3947 | Currently it is only defined for the Intel x86 family. You can set @var{instruction-set} | |
3948 | to either @code{i386} or @code{i8086}. The default is @code{i386}. | |
3949 | @end table | |
3950 | ||
3951 | ||
4eb4cf57 | 3952 | @node Data |
70b88761 RP |
3953 | @chapter Examining Data |
3954 | ||
3955 | @cindex printing data | |
3956 | @cindex examining data | |
3957 | @kindex print | |
3958 | @kindex inspect | |
1041a570 | 3959 | @c "inspect" is not quite a synonym if you are using Epoch, which we do not |
29a2b744 | 3960 | @c document because it is nonstandard... Under Epoch it displays in a |
70b88761 RP |
3961 | @c different window or something like that. |
3962 | The usual way to examine data in your program is with the @code{print} | |
4eb4cf57 | 3963 | command (abbreviated @code{p}), or its synonym @code{inspect}. |
18fae2a8 | 3964 | @ifclear CONLY |
4eb4cf57 | 3965 | It evaluates and prints the value of an expression of the language your |
18fae2a8 | 3966 | program is written in (@pxref{Languages, ,Using @value{GDBN} with Different |
4eb4cf57 | 3967 | Languages}). |
18fae2a8 | 3968 | @end ifclear |
70b88761 | 3969 | |
e0dacfd1 RP |
3970 | @table @code |
3971 | @item print @var{exp} | |
3972 | @itemx print /@var{f} @var{exp} | |
93928b60 RP |
3973 | @var{exp} is an expression (in the source language). By default the |
3974 | value of @var{exp} is printed in a format appropriate to its data type; | |
3975 | you can choose a different format by specifying @samp{/@var{f}}, where | |
3976 | @var{f} is a letter specifying the format; @pxref{Output Formats,,Output | |
3977 | formats}. | |
e0dacfd1 RP |
3978 | |
3979 | @item print | |
3980 | @itemx print /@var{f} | |
18fae2a8 | 3981 | If you omit @var{exp}, @value{GDBN} displays the last value again (from the |
93928b60 | 3982 | @dfn{value history}; @pxref{Value History, ,Value history}). This allows you to |
e0dacfd1 RP |
3983 | conveniently inspect the same value in an alternative format. |
3984 | @end table | |
70b88761 RP |
3985 | |
3986 | A more low-level way of examining data is with the @code{x} command. | |
3987 | It examines data in memory at a specified address and prints it in a | |
93928b60 | 3988 | specified format. @xref{Memory, ,Examining memory}. |
70b88761 | 3989 | |
29a2b744 | 3990 | If you are interested in information about types, or about how the fields |
1d7c3357 RP |
3991 | of a struct |
3992 | @ifclear CONLY | |
3993 | or class | |
18fae2a8 | 3994 | @end ifclear |
1d7c3357 RP |
3995 | are declared, use the @code{ptype @var{exp}} |
3996 | command rather than @code{print}. @xref{Symbols, ,Examining the Symbol Table}. | |
18fae2a8 | 3997 | |
70b88761 | 3998 | @menu |
b80282d5 | 3999 | * Expressions:: Expressions |
ed447b95 RP |
4000 | * Variables:: Program variables |
4001 | * Arrays:: Artificial arrays | |
eb7faec1 | 4002 | * Output Formats:: Output formats |
ed447b95 RP |
4003 | * Memory:: Examining memory |
4004 | * Auto Display:: Automatic display | |
4005 | * Print Settings:: Print settings | |
4006 | * Value History:: Value history | |
4007 | * Convenience Vars:: Convenience variables | |
b80282d5 | 4008 | * Registers:: Registers |
a64a6c2b | 4009 | @ifclear HAVE-FLOAT |
ed447b95 | 4010 | * Floating Point Hardware:: Floating point hardware |
18fae2a8 | 4011 | @end ifclear |
18fae2a8 | 4012 | @end menu |
70b88761 | 4013 | |
4eb4cf57 | 4014 | @node Expressions |
70b88761 RP |
4015 | @section Expressions |
4016 | ||
4017 | @cindex expressions | |
18fae2a8 | 4018 | @code{print} and many other @value{GDBN} commands accept an expression and |
70b88761 | 4019 | compute its value. Any kind of constant, variable or operator defined |
fe715d06 | 4020 | by the programming language you are using is valid in an expression in |
18fae2a8 | 4021 | @value{GDBN}. This includes conditional expressions, function calls, casts |
70b88761 | 4022 | and string constants. It unfortunately does not include symbols defined |
b80282d5 | 4023 | by preprocessor @code{#define} commands. |
70b88761 | 4024 | |
af215b1a | 4025 | @value{GDBN} now supports array constants in expressions input by |
fdfd6134 FF |
4026 | the user. The syntax is @var{@{element, element@dots{}@}}. For example, |
4027 | you can now use the command @code{print @{1, 2, 3@}} to build up an array in | |
af215b1a VM |
4028 | memory that is malloc'd in the target program. |
4029 | ||
18fae2a8 | 4030 | @ifclear CONLY |
c2bbbb22 | 4031 | Because C is so widespread, most of the expressions shown in examples in |
18fae2a8 | 4032 | this manual are in C. @xref{Languages, , Using @value{GDBN} with Different |
c2bbbb22 | 4033 | Languages}, for information on how to use expressions in other |
e251e767 | 4034 | languages. |
c2bbbb22 | 4035 | |
18fae2a8 | 4036 | In this section, we discuss operators that you can use in @value{GDBN} |
e251e767 | 4037 | expressions regardless of your programming language. |
c2bbbb22 | 4038 | |
70b88761 | 4039 | Casts are supported in all languages, not just in C, because it is so |
af215b1a | 4040 | useful to cast a number into a pointer in order to examine a structure |
70b88761 | 4041 | at that address in memory. |
c2bbbb22 | 4042 | @c FIXME: casts supported---Mod2 true? |
18fae2a8 | 4043 | @end ifclear |
70b88761 | 4044 | |
af215b1a VM |
4045 | @value{GDBN} supports these operators, in addition to those common |
4046 | to programming languages: | |
70b88761 RP |
4047 | |
4048 | @table @code | |
4049 | @item @@ | |
4050 | @samp{@@} is a binary operator for treating parts of memory as arrays. | |
93928b60 | 4051 | @xref{Arrays, ,Artificial arrays}, for more information. |
70b88761 RP |
4052 | |
4053 | @item :: | |
4054 | @samp{::} allows you to specify a variable in terms of the file or | |
93928b60 | 4055 | function where it is defined. @xref{Variables, ,Program variables}. |
70b88761 | 4056 | |
fe715d06 RP |
4057 | @cindex @{@var{type}@} |
4058 | @cindex type casting memory | |
4059 | @cindex memory, viewing as typed object | |
4060 | @cindex casts, to view memory | |
af215b1a | 4061 | @item @{@var{type}@} @var{addr} |
70b88761 RP |
4062 | Refers to an object of type @var{type} stored at address @var{addr} in |
4063 | memory. @var{addr} may be any expression whose value is an integer or | |
4064 | pointer (but parentheses are required around binary operators, just as in | |
4065 | a cast). This construct is allowed regardless of what kind of data is | |
1041a570 | 4066 | normally supposed to reside at @var{addr}. |
70b88761 RP |
4067 | @end table |
4068 | ||
4eb4cf57 | 4069 | @node Variables |
93928b60 | 4070 | @section Program variables |
70b88761 RP |
4071 | |
4072 | The most common kind of expression to use is the name of a variable | |
4073 | in your program. | |
4074 | ||
4075 | Variables in expressions are understood in the selected stack frame | |
af215b1a VM |
4076 | (@pxref{Selection, ,Selecting a frame}); they must be either: |
4077 | ||
d056cc31 | 4078 | @itemize @bullet |
af215b1a VM |
4079 | @item |
4080 | global (or static) | |
4081 | @end itemize | |
4082 | ||
4083 | @noindent or | |
4084 | ||
d056cc31 | 4085 | @itemize @bullet |
af215b1a VM |
4086 | @item |
4087 | visible according to the scope rules of the | |
4088 | programming language from the point of execution in that frame | |
4089 | @end itemize | |
4090 | ||
4091 | @noindent This means that in the function | |
70b88761 RP |
4092 | |
4093 | @example | |
4094 | foo (a) | |
4095 | int a; | |
4096 | @{ | |
4097 | bar (a); | |
4098 | @{ | |
4099 | int b = test (); | |
4100 | bar (b); | |
4101 | @} | |
4102 | @} | |
4103 | @end example | |
4104 | ||
4105 | @noindent | |
ed447b95 RP |
4106 | you can examine and use the variable @code{a} whenever your program is |
4107 | executing within the function @code{foo}, but you can only use or | |
4108 | examine the variable @code{b} while your program is executing inside | |
4109 | the block where @code{b} is declared. | |
70b88761 RP |
4110 | |
4111 | @cindex variable name conflict | |
4112 | There is an exception: you can refer to a variable or function whose | |
4113 | scope is a single source file even if the current execution point is not | |
4114 | in this file. But it is possible to have more than one such variable or | |
6ca72cc6 RP |
4115 | function with the same name (in different source files). If that |
4116 | happens, referring to that name has unpredictable effects. If you wish, | |
4117 | you can specify a static variable in a particular function or file, | |
4118 | using the colon-colon notation: | |
70b88761 RP |
4119 | |
4120 | @cindex colon-colon | |
a6d0b6d3 | 4121 | @iftex |
29a2b744 | 4122 | @c info cannot cope with a :: index entry, but why deprive hard copy readers? |
70b88761 | 4123 | @kindex :: |
a6d0b6d3 | 4124 | @end iftex |
70b88761 RP |
4125 | @example |
4126 | @var{file}::@var{variable} | |
6ca72cc6 | 4127 | @var{function}::@var{variable} |
70b88761 RP |
4128 | @end example |
4129 | ||
4130 | @noindent | |
6ca72cc6 | 4131 | Here @var{file} or @var{function} is the name of the context for the |
6c380b13 | 4132 | static @var{variable}. In the case of file names, you can use quotes to |
18fae2a8 | 4133 | make sure @value{GDBN} parses the file name as a single word---for example, |
6c380b13 RP |
4134 | to print a global value of @code{x} defined in @file{f2.c}: |
4135 | ||
4136 | @example | |
18fae2a8 | 4137 | (@value{GDBP}) p 'f2.c'::x |
6c380b13 | 4138 | @end example |
70b88761 | 4139 | |
18fae2a8 | 4140 | @ifclear CONLY |
c2bbbb22 | 4141 | @cindex C++ scope resolution |
70b88761 | 4142 | This use of @samp{::} is very rarely in conflict with the very similar |
18fae2a8 RP |
4143 | use of the same notation in C++. @value{GDBN} also supports use of the C++ |
4144 | scope resolution operator in @value{GDBN} expressions. | |
ed447b95 RP |
4145 | @c FIXME: Um, so what happens in one of those rare cases where it's in |
4146 | @c conflict?? --mew | |
18fae2a8 | 4147 | @end ifclear |
70b88761 | 4148 | |
3d3ab540 RP |
4149 | @cindex wrong values |
4150 | @cindex variable values, wrong | |
4151 | @quotation | |
4152 | @emph{Warning:} Occasionally, a local variable may appear to have the | |
b0157555 RP |
4153 | wrong value at certain points in a function---just after entry to a new |
4154 | scope, and just before exit. | |
3d3ab540 | 4155 | @end quotation |
b0157555 | 4156 | You may see this problem when you are stepping by machine instructions. |
af215b1a | 4157 | This is because, on most machines, it takes more than one instruction to |
b0157555 RP |
4158 | set up a stack frame (including local variable definitions); if you are |
4159 | stepping by machine instructions, variables may appear to have the wrong | |
4160 | values until the stack frame is completely built. On exit, it usually | |
4161 | also takes more than one machine instruction to destroy a stack frame; | |
4162 | after you begin stepping through that group of instructions, local | |
4163 | variable definitions may be gone. | |
3d3ab540 | 4164 | |
4eb4cf57 | 4165 | @node Arrays |
93928b60 | 4166 | @section Artificial arrays |
70b88761 RP |
4167 | |
4168 | @cindex artificial array | |
4169 | @kindex @@ | |
4170 | It is often useful to print out several successive objects of the | |
4171 | same type in memory; a section of an array, or an array of | |
4172 | dynamically determined size for which only a pointer exists in the | |
4173 | program. | |
4174 | ||
fe715d06 RP |
4175 | You can do this by referring to a contiguous span of memory as an |
4176 | @dfn{artificial array}, using the binary operator @samp{@@}. The left | |
af215b1a VM |
4177 | operand of @samp{@@} should be the first element of the desired array |
4178 | and be an individual object. The right operand should be the desired length | |
fe715d06 RP |
4179 | of the array. The result is an array value whose elements are all of |
4180 | the type of the left argument. The first element is actually the left | |
4181 | argument; the second element comes from bytes of memory immediately | |
4182 | following those that hold the first element, and so on. Here is an | |
4183 | example. If a program says | |
70b88761 RP |
4184 | |
4185 | @example | |
4186 | int *array = (int *) malloc (len * sizeof (int)); | |
4187 | @end example | |
4188 | ||
4189 | @noindent | |
4190 | you can print the contents of @code{array} with | |
4191 | ||
4192 | @example | |
4193 | p *array@@len | |
4194 | @end example | |
4195 | ||
4196 | The left operand of @samp{@@} must reside in memory. Array values made | |
4197 | with @samp{@@} in this way behave just like other arrays in terms of | |
4198 | subscripting, and are coerced to pointers when used in expressions. | |
4199 | Artificial arrays most often appear in expressions via the value history | |
7640fe71 | 4200 | (@pxref{Value History, ,Value history}), after printing one out. |
70b88761 | 4201 | |
27648f26 PB |
4202 | Another way to create an artificial array is to use a cast. |
4203 | This re-interprets a value as if it were an array. | |
4204 | The value need not be in memory: | |
4205 | @example | |
4206 | (@value{GDBP}) p/x (short[2])0x12345678 | |
4207 | $1 = @{0x1234, 0x5678@} | |
4208 | @end example | |
4209 | ||
4210 | As a convenience, if you leave the array length out (as in | |
4211 | @samp{(@var{type})[])@var{value}}) gdb calculates the size to fill | |
4212 | the value (as @samp{sizeof(@var{value})/sizeof(@var{type})}: | |
4213 | @example | |
4214 | (@value{GDBP}) p/x (short[])0x12345678 | |
4215 | $2 = @{0x1234, 0x5678@} | |
4216 | @end example | |
4217 | ||
1041a570 | 4218 | Sometimes the artificial array mechanism is not quite enough; in |
3d3ab540 | 4219 | moderately complex data structures, the elements of interest may not |
1041a570 RP |
4220 | actually be adjacent---for example, if you are interested in the values |
4221 | of pointers in an array. One useful work-around in this situation is | |
4222 | to use a convenience variable (@pxref{Convenience Vars, ,Convenience | |
93928b60 | 4223 | variables}) as a counter in an expression that prints the first |
1041a570 RP |
4224 | interesting value, and then repeat that expression via @key{RET}. For |
4225 | instance, suppose you have an array @code{dtab} of pointers to | |
4226 | structures, and you are interested in the values of a field @code{fv} | |
4227 | in each structure. Here is an example of what you might type: | |
4228 | ||
3d3ab540 RP |
4229 | @example |
4230 | set $i = 0 | |
4231 | p dtab[$i++]->fv | |
4232 | @key{RET} | |
4233 | @key{RET} | |
4234 | @dots{} | |
4235 | @end example | |
4236 | ||
ed447b95 | 4237 | @node Output Formats |
70b88761 RP |
4238 | @section Output formats |
4239 | ||
4240 | @cindex formatted output | |
4241 | @cindex output formats | |
18fae2a8 | 4242 | By default, @value{GDBN} prints a value according to its data type. Sometimes |
70b88761 RP |
4243 | this is not what you want. For example, you might want to print a number |
4244 | in hex, or a pointer in decimal. Or you might want to view data in memory | |
4245 | at a certain address as a character string or as an instruction. To do | |
4246 | these things, specify an @dfn{output format} when you print a value. | |
4247 | ||
4248 | The simplest use of output formats is to say how to print a value | |
4249 | already computed. This is done by starting the arguments of the | |
4250 | @code{print} command with a slash and a format letter. The format | |
4251 | letters supported are: | |
4252 | ||
4253 | @table @code | |
4254 | @item x | |
4255 | Regard the bits of the value as an integer, and print the integer in | |
4256 | hexadecimal. | |
4257 | ||
4258 | @item d | |
4259 | Print as integer in signed decimal. | |
4260 | ||
4261 | @item u | |
4262 | Print as integer in unsigned decimal. | |
4263 | ||
4264 | @item o | |
4265 | Print as integer in octal. | |
4266 | ||
4267 | @item t | |
4268 | Print as integer in binary. The letter @samp{t} stands for ``two''. | |
fe715d06 RP |
4269 | @footnote{@samp{b} cannot be used because these format letters are also |
4270 | used with the @code{x} command, where @samp{b} stands for ``byte''; | |
4271 | @pxref{Memory,,Examining memory}.} | |
70b88761 RP |
4272 | |
4273 | @item a | |
9a27b06e RP |
4274 | @cindex unknown address, locating |
4275 | Print as an address, both absolute in hexadecimal and as an offset from | |
4276 | the nearest preceding symbol. You can use this format used to discover | |
4277 | where (in what function) an unknown address is located: | |
1041a570 | 4278 | |
70b88761 | 4279 | @example |
18fae2a8 RP |
4280 | (@value{GDBP}) p/a 0x54320 |
4281 | $3 = 0x54320 <_initialize_vx+396> | |
70b88761 RP |
4282 | @end example |
4283 | ||
70b88761 RP |
4284 | @item c |
4285 | Regard as an integer and print it as a character constant. | |
4286 | ||
4287 | @item f | |
4288 | Regard the bits of the value as a floating point number and print | |
4289 | using typical floating point syntax. | |
4290 | @end table | |
4291 | ||
4292 | For example, to print the program counter in hex (@pxref{Registers}), type | |
4293 | ||
4294 | @example | |
4295 | p/x $pc | |
4296 | @end example | |
4297 | ||
4298 | @noindent | |
4299 | Note that no space is required before the slash; this is because command | |
18fae2a8 | 4300 | names in @value{GDBN} cannot contain a slash. |
70b88761 RP |
4301 | |
4302 | To reprint the last value in the value history with a different format, | |
4303 | you can use the @code{print} command with just a format and no | |
4304 | expression. For example, @samp{p/x} reprints the last value in hex. | |
4305 | ||
4eb4cf57 | 4306 | @node Memory |
93928b60 | 4307 | @section Examining memory |
70b88761 | 4308 | |
1041a570 RP |
4309 | You can use the command @code{x} (for ``examine'') to examine memory in |
4310 | any of several formats, independently of your program's data types. | |
4311 | ||
70b88761 RP |
4312 | @cindex examining memory |
4313 | @table @code | |
4314 | @kindex x | |
cedaf8bc RP |
4315 | @item x/@var{nfu} @var{addr} |
4316 | @itemx x @var{addr} | |
4317 | @itemx x | |
ed447b95 | 4318 | Use the @code{x} command to examine memory. |
1041a570 RP |
4319 | @end table |
4320 | ||
4321 | @var{n}, @var{f}, and @var{u} are all optional parameters that specify how | |
4322 | much memory to display and how to format it; @var{addr} is an | |
cedaf8bc RP |
4323 | expression giving the address where you want to start displaying memory. |
4324 | If you use defaults for @var{nfu}, you need not type the slash @samp{/}. | |
4325 | Several commands set convenient defaults for @var{addr}. | |
70b88761 | 4326 | |
1041a570 RP |
4327 | @table @r |
4328 | @item @var{n}, the repeat count | |
4329 | The repeat count is a decimal integer; the default is 1. It specifies | |
4330 | how much memory (counting by units @var{u}) to display. | |
cedaf8bc RP |
4331 | @c This really is **decimal**; unaffected by 'set radix' as of GDB |
4332 | @c 4.1.2. | |
70b88761 | 4333 | |
1041a570 RP |
4334 | @item @var{f}, the display format |
4335 | The display format is one of the formats used by @code{print}, | |
af215b1a VM |
4336 | @samp{s} (null-terminated string), or @samp{i} (machine instruction). |
4337 | The default is @samp{x} (hexadecimal) initially. | |
4338 | The default changes each time you use either @code{x} or @code{print}. | |
70b88761 | 4339 | |
1041a570 RP |
4340 | @item @var{u}, the unit size |
4341 | The unit size is any of | |
ed447b95 | 4342 | |
70b88761 RP |
4343 | @table @code |
4344 | @item b | |
cedaf8bc | 4345 | Bytes. |
70b88761 | 4346 | @item h |
cedaf8bc | 4347 | Halfwords (two bytes). |
70b88761 | 4348 | @item w |
cedaf8bc | 4349 | Words (four bytes). This is the initial default. |
70b88761 | 4350 | @item g |
cedaf8bc | 4351 | Giant words (eight bytes). |
70b88761 RP |
4352 | @end table |
4353 | ||
cedaf8bc RP |
4354 | Each time you specify a unit size with @code{x}, that size becomes the |
4355 | default unit the next time you use @code{x}. (For the @samp{s} and | |
4356 | @samp{i} formats, the unit size is ignored and is normally not written.) | |
4357 | ||
1041a570 | 4358 | @item @var{addr}, starting display address |
18fae2a8 | 4359 | @var{addr} is the address where you want @value{GDBN} to begin displaying |
cedaf8bc RP |
4360 | memory. The expression need not have a pointer value (though it may); |
4361 | it is always interpreted as an integer address of a byte of memory. | |
1041a570 | 4362 | @xref{Expressions, ,Expressions}, for more information on expressions. The default for |
cedaf8bc RP |
4363 | @var{addr} is usually just after the last address examined---but several |
4364 | other commands also set the default address: @code{info breakpoints} (to | |
4365 | the address of the last breakpoint listed), @code{info line} (to the | |
4366 | starting address of a line), and @code{print} (if you use it to display | |
4367 | a value from memory). | |
1041a570 | 4368 | @end table |
70b88761 | 4369 | |
cedaf8bc RP |
4370 | For example, @samp{x/3uh 0x54320} is a request to display three halfwords |
4371 | (@code{h}) of memory, formatted as unsigned decimal integers (@samp{u}), | |
4372 | starting at address @code{0x54320}. @samp{x/4xw $sp} prints the four | |
4373 | words (@samp{w}) of memory above the stack pointer (here, @samp{$sp}; | |
4374 | @pxref{Registers}) in hexadecimal (@samp{x}). | |
70b88761 | 4375 | |
cedaf8bc | 4376 | Since the letters indicating unit sizes are all distinct from the |
29a2b744 | 4377 | letters specifying output formats, you do not have to remember whether |
9a27b06e | 4378 | unit size or format comes first; either order works. The output |
cedaf8bc | 4379 | specifications @samp{4xw} and @samp{4wx} mean exactly the same thing. |
9a27b06e | 4380 | (However, the count @var{n} must come first; @samp{wx4} does not work.) |
cedaf8bc RP |
4381 | |
4382 | Even though the unit size @var{u} is ignored for the formats @samp{s} | |
4383 | and @samp{i}, you might still want to use a count @var{n}; for example, | |
4384 | @samp{3i} specifies that you want to see three machine instructions, | |
4385 | including any operands. The command @code{disassemble} gives an | |
4386 | alternative way of inspecting machine instructions; @pxref{Machine | |
93928b60 | 4387 | Code,,Source and machine code}. |
cedaf8bc RP |
4388 | |
4389 | All the defaults for the arguments to @code{x} are designed to make it | |
4390 | easy to continue scanning memory with minimal specifications each time | |
1041a570 | 4391 | you use @code{x}. For example, after you have inspected three machine |
cedaf8bc RP |
4392 | instructions with @samp{x/3i @var{addr}}, you can inspect the next seven |
4393 | with just @samp{x/7}. If you use @key{RET} to repeat the @code{x} command, | |
4394 | the repeat count @var{n} is used again; the other arguments default as | |
4395 | for successive uses of @code{x}. | |
70b88761 | 4396 | |
c338a2fd | 4397 | @cindex @code{$_}, @code{$__}, and value history |
cedaf8bc | 4398 | The addresses and contents printed by the @code{x} command are not saved |
70b88761 | 4399 | in the value history because there is often too much of them and they |
18fae2a8 | 4400 | would get in the way. Instead, @value{GDBN} makes these values available for |
70b88761 RP |
4401 | subsequent use in expressions as values of the convenience variables |
4402 | @code{$_} and @code{$__}. After an @code{x} command, the last address | |
4403 | examined is available for use in expressions in the convenience variable | |
4404 | @code{$_}. The contents of that address, as examined, are available in | |
4405 | the convenience variable @code{$__}. | |
4406 | ||
4407 | If the @code{x} command has a repeat count, the address and contents saved | |
4408 | are from the last memory unit printed; this is not the same as the last | |
4409 | address printed if several units were printed on the last line of output. | |
4410 | ||
4eb4cf57 | 4411 | @node Auto Display |
93928b60 | 4412 | @section Automatic display |
70b88761 RP |
4413 | @cindex automatic display |
4414 | @cindex display of expressions | |
4415 | ||
4416 | If you find that you want to print the value of an expression frequently | |
4417 | (to see how it changes), you might want to add it to the @dfn{automatic | |
9a27b06e | 4418 | display list} so that @value{GDBN} prints its value each time your program stops. |
70b88761 RP |
4419 | Each expression added to the list is given a number to identify it; |
4420 | to remove an expression from the list, you specify that number. | |
4421 | The automatic display looks like this: | |
4422 | ||
4423 | @example | |
4424 | 2: foo = 38 | |
4425 | 3: bar[5] = (struct hack *) 0x3804 | |
4426 | @end example | |
4427 | ||
4428 | @noindent | |
ed447b95 | 4429 | This display shows item numbers, expressions and their current values. As with |
70b88761 RP |
4430 | displays you request manually using @code{x} or @code{print}, you can |
4431 | specify the output format you prefer; in fact, @code{display} decides | |
4432 | whether to use @code{print} or @code{x} depending on how elaborate your | |
4433 | format specification is---it uses @code{x} if you specify a unit size, | |
4434 | or one of the two formats (@samp{i} and @samp{s}) that are only | |
4435 | supported by @code{x}; otherwise it uses @code{print}. | |
4436 | ||
4437 | @table @code | |
70b88761 | 4438 | @kindex display |
af215b1a | 4439 | @item display @var{exp} |
70b88761 | 4440 | Add the expression @var{exp} to the list of expressions to display |
1041a570 | 4441 | each time your program stops. @xref{Expressions, ,Expressions}. |
70b88761 | 4442 | |
9a27b06e | 4443 | @code{display} does not repeat if you press @key{RET} again after using it. |
70b88761 RP |
4444 | |
4445 | @item display/@var{fmt} @var{exp} | |
4446 | For @var{fmt} specifying only a display format and not a size or | |
4447 | count, add the expression @var{exp} to the auto-display list but | |
7640fe71 | 4448 | arrange to display it each time in the specified format @var{fmt}. |
ed447b95 | 4449 | @xref{Output Formats,,Output formats}. |
70b88761 RP |
4450 | |
4451 | @item display/@var{fmt} @var{addr} | |
4452 | For @var{fmt} @samp{i} or @samp{s}, or including a unit-size or a | |
4453 | number of units, add the expression @var{addr} as a memory address to | |
29a2b744 | 4454 | be examined each time your program stops. Examining means in effect |
93928b60 | 4455 | doing @samp{x/@var{fmt} @var{addr}}. @xref{Memory, ,Examining memory}. |
70b88761 RP |
4456 | @end table |
4457 | ||
4458 | For example, @samp{display/i $pc} can be helpful, to see the machine | |
4459 | instruction about to be executed each time execution stops (@samp{$pc} | |
4460 | is a common name for the program counter; @pxref{Registers}). | |
4461 | ||
4462 | @table @code | |
70b88761 RP |
4463 | @kindex delete display |
4464 | @kindex undisplay | |
af215b1a VM |
4465 | @item undisplay @var{dnums}@dots{} |
4466 | @itemx delete display @var{dnums}@dots{} | |
70b88761 RP |
4467 | Remove item numbers @var{dnums} from the list of expressions to display. |
4468 | ||
9a27b06e | 4469 | @code{undisplay} does not repeat if you press @key{RET} after using it. |
70b88761 RP |
4470 | (Otherwise you would just get the error @samp{No display number @dots{}}.) |
4471 | ||
70b88761 | 4472 | @kindex disable display |
af215b1a | 4473 | @item disable display @var{dnums}@dots{} |
70b88761 RP |
4474 | Disable the display of item numbers @var{dnums}. A disabled display |
4475 | item is not printed automatically, but is not forgotten. It may be | |
4476 | enabled again later. | |
4477 | ||
70b88761 | 4478 | @kindex enable display |
af215b1a | 4479 | @item enable display @var{dnums}@dots{} |
70b88761 RP |
4480 | Enable display of item numbers @var{dnums}. It becomes effective once |
4481 | again in auto display of its expression, until you specify otherwise. | |
4482 | ||
4483 | @item display | |
4484 | Display the current values of the expressions on the list, just as is | |
29a2b744 | 4485 | done when your program stops. |
70b88761 | 4486 | |
70b88761 | 4487 | @kindex info display |
af215b1a | 4488 | @item info display |
70b88761 RP |
4489 | Print the list of expressions previously set up to display |
4490 | automatically, each one with its item number, but without showing the | |
4491 | values. This includes disabled expressions, which are marked as such. | |
4492 | It also includes expressions which would not be displayed right now | |
4493 | because they refer to automatic variables not currently available. | |
4494 | @end table | |
4495 | ||
4496 | If a display expression refers to local variables, then it does not make | |
4497 | sense outside the lexical context for which it was set up. Such an | |
4498 | expression is disabled when execution enters a context where one of its | |
4499 | variables is not defined. For example, if you give the command | |
4500 | @code{display last_char} while inside a function with an argument | |
9a27b06e | 4501 | @code{last_char}, @value{GDBN} displays this argument while your program |
70b88761 | 4502 | continues to stop inside that function. When it stops elsewhere---where |
9a27b06e RP |
4503 | there is no variable @code{last_char}---the display is disabled |
4504 | automatically. The next time your program stops where @code{last_char} | |
4505 | is meaningful, you can enable the display expression once again. | |
70b88761 | 4506 | |
4eb4cf57 | 4507 | @node Print Settings |
93928b60 | 4508 | @section Print settings |
70b88761 RP |
4509 | |
4510 | @cindex format options | |
4511 | @cindex print settings | |
18fae2a8 | 4512 | @value{GDBN} provides the following ways to control how arrays, structures, |
e251e767 | 4513 | and symbols are printed. |
70b88761 RP |
4514 | |
4515 | @noindent | |
4516 | These settings are useful for debugging programs in any language: | |
4517 | ||
4518 | @table @code | |
af215b1a | 4519 | @kindex set print address |
70b88761 | 4520 | @item set print address |
6b51acad | 4521 | @itemx set print address on |
9a27b06e | 4522 | @value{GDBN} prints memory addresses showing the location of stack |
70b88761 RP |
4523 | traces, structure values, pointer values, breakpoints, and so forth, |
4524 | even when it also displays the contents of those addresses. The default | |
af215b1a | 4525 | is @code{on}. For example, this is what a stack frame display looks like with |
70b88761 | 4526 | @code{set print address on}: |
1041a570 | 4527 | |
70b88761 | 4528 | @smallexample |
1041a570 | 4529 | @group |
18fae2a8 | 4530 | (@value{GDBP}) f |
e251e767 | 4531 | #0 set_quotes (lq=0x34c78 "<<", rq=0x34c88 ">>") |
70b88761 | 4532 | at input.c:530 |
b80282d5 | 4533 | 530 if (lquote != def_lquote) |
1041a570 | 4534 | @end group |
70b88761 RP |
4535 | @end smallexample |
4536 | ||
4537 | @item set print address off | |
4538 | Do not print addresses when displaying their contents. For example, | |
4539 | this is the same stack frame displayed with @code{set print address off}: | |
1041a570 | 4540 | |
d55320a0 | 4541 | @smallexample |
1041a570 | 4542 | @group |
18fae2a8 RP |
4543 | (@value{GDBP}) set print addr off |
4544 | (@value{GDBP}) f | |
70b88761 | 4545 | #0 set_quotes (lq="<<", rq=">>") at input.c:530 |
b80282d5 | 4546 | 530 if (lquote != def_lquote) |
1041a570 | 4547 | @end group |
d55320a0 | 4548 | @end smallexample |
70b88761 | 4549 | |
fe715d06 RP |
4550 | You can use @samp{set print address off} to eliminate all machine |
4551 | dependent displays from the @value{GDBN} interface. For example, with | |
4552 | @code{print address off}, you should get the same text for backtraces on | |
4553 | all machines---whether or not they involve pointer arguments. | |
4554 | ||
70b88761 | 4555 | @kindex show print address |
af215b1a | 4556 | @item show print address |
70b88761 | 4557 | Show whether or not addresses are to be printed. |
14621224 JK |
4558 | @end table |
4559 | ||
4560 | When @value{GDBN} prints a symbolic address, it normally prints the | |
4561 | closest earlier symbol plus an offset. If that symbol does not uniquely | |
4562 | identify the address (for example, it is a name whose scope is a single | |
af215b1a | 4563 | source file), you may need to clarify. One way to do this is with |
9a27b06e | 4564 | @code{info line}, for example @samp{info line *0x4537}. Alternately, |
14621224 JK |
4565 | you can set @value{GDBN} to print the source file and line number when |
4566 | it prints a symbolic address: | |
4567 | ||
4568 | @table @code | |
14621224 | 4569 | @kindex set print symbol-filename |
af215b1a | 4570 | @item set print symbol-filename on |
14621224 JK |
4571 | Tell @value{GDBN} to print the source file name and line number of a |
4572 | symbol in the symbolic form of an address. | |
4573 | ||
4574 | @item set print symbol-filename off | |
4575 | Do not print source file name and line number of a symbol. This is the | |
4576 | default. | |
4577 | ||
14621224 | 4578 | @kindex show print symbol-filename |
af215b1a | 4579 | @item show print symbol-filename |
14621224 JK |
4580 | Show whether or not @value{GDBN} will print the source file name and |
4581 | line number of a symbol in the symbolic form of an address. | |
4582 | @end table | |
4583 | ||
9a27b06e RP |
4584 | Another situation where it is helpful to show symbol filenames and line |
4585 | numbers is when disassembling code; @value{GDBN} shows you the line | |
5986c8ea JG |
4586 | number and source file that corresponds to each instruction. |
4587 | ||
14621224 JK |
4588 | Also, you may wish to see the symbolic form only if the address being |
4589 | printed is reasonably close to the closest earlier symbol: | |
4590 | ||
4591 | @table @code | |
14621224 | 4592 | @kindex set print max-symbolic-offset |
af215b1a | 4593 | @item set print max-symbolic-offset @var{max-offset} |
14621224 JK |
4594 | Tell @value{GDBN} to only display the symbolic form of an address if the |
4595 | offset between the closest earlier symbol and the address is less than | |
af215b1a VM |
4596 | @var{max-offset}. The default is 0, which tells @value{GDBN} |
4597 | to always print the symbolic form of an address if any symbol precedes it. | |
14621224 | 4598 | |
14621224 | 4599 | @kindex show print max-symbolic-offset |
af215b1a | 4600 | @item show print max-symbolic-offset |
9a27b06e | 4601 | Ask how large the maximum offset is that @value{GDBN} prints in a |
14621224 JK |
4602 | symbolic address. |
4603 | @end table | |
70b88761 | 4604 | |
9a27b06e RP |
4605 | @cindex wild pointer, interpreting |
4606 | @cindex pointer, finding referent | |
4607 | If you have a pointer and you are not sure where it points, try | |
ec35141c JK |
4608 | @samp{set print symbol-filename on}. Then you can determine the name |
4609 | and source file location of the variable where it points, using | |
4610 | @samp{p/a @var{pointer}}. This interprets the address in symbolic form. | |
4611 | For example, here @value{GDBN} shows that a variable @code{ptt} points | |
4612 | at another variable @code{t}, defined in @file{hi2.c}: | |
9a27b06e RP |
4613 | |
4614 | @example | |
9a27b06e RP |
4615 | (@value{GDBP}) set print symbol-filename on |
4616 | (@value{GDBP}) p/a ptt | |
4617 | $4 = 0xe008 <t in hi2.c> | |
4618 | @end example | |
4619 | ||
4620 | @quotation | |
4621 | @emph{Warning:} For pointers that point to a local variable, @samp{p/a} | |
4622 | does not show the symbol name and filename of the referent, even with | |
4623 | the appropriate @code{set print} options turned on. | |
4624 | @end quotation | |
4625 | ||
5986c8ea JG |
4626 | Other settings control how different kinds of objects are printed: |
4627 | ||
14621224 | 4628 | @table @code |
af215b1a | 4629 | @kindex set print array |
70b88761 RP |
4630 | @item set print array |
4631 | @itemx set print array on | |
af215b1a | 4632 | Pretty print arrays. This format is more convenient to read, |
70b88761 RP |
4633 | but uses more space. The default is off. |
4634 | ||
fe715d06 | 4635 | @item set print array off |
70b88761 RP |
4636 | Return to compressed format for arrays. |
4637 | ||
70b88761 | 4638 | @kindex show print array |
af215b1a | 4639 | @item show print array |
70b88761 | 4640 | Show whether compressed or pretty format is selected for displaying |
e251e767 | 4641 | arrays. |
70b88761 | 4642 | |
70b88761 | 4643 | @kindex set print elements |
af215b1a VM |
4644 | @item set print elements @var{number-of-elements} |
4645 | Set a limit on how many elements of an array @value{GDBN} will print. | |
9a27b06e | 4646 | If @value{GDBN} is printing a large array, it stops printing after it has |
70b88761 RP |
4647 | printed the number of elements set by the @code{set print elements} command. |
4648 | This limit also applies to the display of strings. | |
af215b1a | 4649 | Setting @var{number-of-elements} to zero means that the printing is unlimited. |
70b88761 | 4650 | |
70b88761 | 4651 | @kindex show print elements |
af215b1a VM |
4652 | @item show print elements |
4653 | Display the number of elements of a large array that @value{GDBN} will print. | |
4654 | If the number is 0, then the printing is unlimited. | |
4655 | ||
4656 | @kindex set print null-stop | |
4657 | @item set print null-stop | |
4658 | Cause @value{GDBN} to stop printing the characters of an array when the first | |
4659 | @sc{NULL} is encountered. This is useful when large arrays actually | |
4660 | contain only short strings. | |
70b88761 | 4661 | |
70b88761 | 4662 | @kindex set print pretty |
af215b1a VM |
4663 | @item set print pretty on |
4664 | Cause @value{GDBN} to print structures in an indented format with one member | |
4665 | per line, like this: | |
70b88761 | 4666 | |
d55320a0 | 4667 | @smallexample |
1041a570 | 4668 | @group |
70b88761 RP |
4669 | $1 = @{ |
4670 | next = 0x0, | |
4671 | flags = @{ | |
4672 | sweet = 1, | |
4673 | sour = 1 | |
4674 | @}, | |
4675 | meat = 0x54 "Pork" | |
4676 | @} | |
1041a570 | 4677 | @end group |
d55320a0 | 4678 | @end smallexample |
70b88761 RP |
4679 | |
4680 | @item set print pretty off | |
18fae2a8 | 4681 | Cause @value{GDBN} to print structures in a compact format, like this: |
70b88761 RP |
4682 | |
4683 | @smallexample | |
1041a570 | 4684 | @group |
38962738 RP |
4685 | $1 = @{next = 0x0, flags = @{sweet = 1, sour = 1@}, \ |
4686 | meat = 0x54 "Pork"@} | |
1041a570 | 4687 | @end group |
70b88761 RP |
4688 | @end smallexample |
4689 | ||
4690 | @noindent | |
4691 | This is the default format. | |
4692 | ||
70b88761 | 4693 | @kindex show print pretty |
af215b1a | 4694 | @item show print pretty |
9a27b06e | 4695 | Show which format @value{GDBN} is using to print structures. |
70b88761 | 4696 | |
f2857bd9 | 4697 | @kindex set print sevenbit-strings |
af215b1a | 4698 | @item set print sevenbit-strings on |
e251e767 | 4699 | Print using only seven-bit characters; if this option is set, |
9a27b06e RP |
4700 | @value{GDBN} displays any eight-bit characters (in strings or |
4701 | character values) using the notation @code{\}@var{nnn}. This setting is | |
4702 | best if you are working in English (@sc{ascii}) and you use the | |
4703 | high-order bit of characters as a marker or ``meta'' bit. | |
70b88761 RP |
4704 | |
4705 | @item set print sevenbit-strings off | |
9a27b06e RP |
4706 | Print full eight-bit characters. This allows the use of more |
4707 | international character sets, and is the default. | |
70b88761 | 4708 | |
f2857bd9 | 4709 | @kindex show print sevenbit-strings |
af215b1a | 4710 | @item show print sevenbit-strings |
9a27b06e | 4711 | Show whether or not @value{GDBN} is printing only seven-bit characters. |
70b88761 | 4712 | |
70b88761 | 4713 | @kindex set print union |
af215b1a VM |
4714 | @item set print union on |
4715 | Tell @value{GDBN} to print unions which are contained in structures. This | |
4716 | is the default setting. | |
70b88761 RP |
4717 | |
4718 | @item set print union off | |
18fae2a8 | 4719 | Tell @value{GDBN} not to print unions which are contained in structures. |
70b88761 | 4720 | |
70b88761 | 4721 | @kindex show print union |
af215b1a | 4722 | @item show print union |
18fae2a8 | 4723 | Ask @value{GDBN} whether or not it will print unions which are contained in |
e251e767 | 4724 | structures. |
70b88761 RP |
4725 | |
4726 | For example, given the declarations | |
4727 | ||
4728 | @smallexample | |
4729 | typedef enum @{Tree, Bug@} Species; | |
4730 | typedef enum @{Big_tree, Acorn, Seedling@} Tree_forms; | |
203eea5d RP |
4731 | typedef enum @{Caterpillar, Cocoon, Butterfly@} |
4732 | Bug_forms; | |
70b88761 RP |
4733 | |
4734 | struct thing @{ | |
4735 | Species it; | |
4736 | union @{ | |
4737 | Tree_forms tree; | |
4738 | Bug_forms bug; | |
4739 | @} form; | |
4740 | @}; | |
4741 | ||
4742 | struct thing foo = @{Tree, @{Acorn@}@}; | |
4743 | @end smallexample | |
4744 | ||
4745 | @noindent | |
4746 | with @code{set print union on} in effect @samp{p foo} would print | |
4747 | ||
4748 | @smallexample | |
4749 | $1 = @{it = Tree, form = @{tree = Acorn, bug = Cocoon@}@} | |
4750 | @end smallexample | |
4751 | ||
4752 | @noindent | |
4753 | and with @code{set print union off} in effect it would print | |
4754 | ||
4755 | @smallexample | |
4756 | $1 = @{it = Tree, form = @{...@}@} | |
4757 | @end smallexample | |
4758 | @end table | |
4759 | ||
1d7c3357 | 4760 | @ifclear CONLY |
d55320a0 | 4761 | @need 1000 |
70b88761 RP |
4762 | @noindent |
4763 | These settings are of interest when debugging C++ programs: | |
4764 | ||
4765 | @table @code | |
af215b1a VM |
4766 | @cindex demangling |
4767 | @kindex set print demangle | |
e251e767 RP |
4768 | @item set print demangle |
4769 | @itemx set print demangle on | |
fe715d06 RP |
4770 | Print C++ names in their source form rather than in the encoded |
4771 | (``mangled'') form passed to the assembler and linker for type-safe | |
4772 | linkage. The default is @samp{on}. | |
70b88761 | 4773 | |
70b88761 | 4774 | @kindex show print demangle |
af215b1a | 4775 | @item show print demangle |
9a27b06e | 4776 | Show whether C++ names are printed in mangled or demangled form. |
70b88761 | 4777 | |
af215b1a | 4778 | @kindex set print asm-demangle |
e251e767 RP |
4779 | @item set print asm-demangle |
4780 | @itemx set print asm-demangle on | |
70b88761 RP |
4781 | Print C++ names in their source form rather than their mangled form, even |
4782 | in assembler code printouts such as instruction disassemblies. | |
4783 | The default is off. | |
4784 | ||
70b88761 | 4785 | @kindex show print asm-demangle |
af215b1a | 4786 | @item show print asm-demangle |
9a27b06e | 4787 | Show whether C++ names in assembly listings are printed in mangled |
70b88761 RP |
4788 | or demangled form. |
4789 | ||
fe715d06 RP |
4790 | @kindex set demangle-style |
4791 | @cindex C++ symbol decoding style | |
4792 | @cindex symbol decoding style, C++ | |
af215b1a | 4793 | @item set demangle-style @var{style} |
fe715d06 RP |
4794 | Choose among several encoding schemes used by different compilers to |
4795 | represent C++ names. The choices for @var{style} are currently: | |
4796 | ||
4797 | @table @code | |
4798 | @item auto | |
4799 | Allow @value{GDBN} to choose a decoding style by inspecting your program. | |
4800 | ||
4801 | @item gnu | |
af215b1a VM |
4802 | Decode based on the @sc{gnu} C++ compiler (@code{g++}) encoding algorithm. |
4803 | This is the default. | |
fe715d06 RP |
4804 | |
4805 | @item lucid | |
4806 | Decode based on the Lucid C++ compiler (@code{lcc}) encoding algorithm. | |
4807 | ||
a1eff6c2 | 4808 | @item arm |
fe715d06 | 4809 | Decode using the algorithm in the @cite{C++ Annotated Reference Manual}. |
a1eff6c2 RP |
4810 | @strong{Warning:} this setting alone is not sufficient to allow |
4811 | debugging @code{cfront}-generated executables. @value{GDBN} would | |
4812 | require further enhancement to permit that. | |
af215b1a VM |
4813 | |
4814 | @item foo | |
4815 | Show the list of formats. | |
fe715d06 RP |
4816 | @end table |
4817 | ||
fe715d06 | 4818 | @kindex show demangle-style |
af215b1a | 4819 | @item show demangle-style |
fe715d06 RP |
4820 | Display the encoding style currently in use for decoding C++ symbols. |
4821 | ||
af215b1a | 4822 | @kindex set print object |
70b88761 RP |
4823 | @item set print object |
4824 | @itemx set print object on | |
70b88761 RP |
4825 | When displaying a pointer to an object, identify the @emph{actual} |
4826 | (derived) type of the object rather than the @emph{declared} type, using | |
4827 | the virtual function table. | |
4828 | ||
4829 | @item set print object off | |
4830 | Display only the declared type of objects, without reference to the | |
4831 | virtual function table. This is the default setting. | |
4832 | ||
70b88761 | 4833 | @kindex show print object |
af215b1a | 4834 | @item show print object |
9a27b06e | 4835 | Show whether actual, or declared, object types are displayed. |
70b88761 | 4836 | |
be255497 PS |
4837 | @kindex set print static-members |
4838 | @item set print static-members | |
4839 | @itemx set print static-members on | |
4840 | Print static members when displaying a C++ object. The default is on. | |
4841 | ||
4842 | @item set print static-members off | |
4843 | Do not print static members when displaying a C++ object. | |
4844 | ||
4845 | @kindex show print static-members | |
4846 | @item show print static-members | |
4847 | Show whether C++ static members are printed, or not. | |
4848 | ||
af215b1a | 4849 | @kindex set print vtbl |
e251e767 RP |
4850 | @item set print vtbl |
4851 | @itemx set print vtbl on | |
70b88761 RP |
4852 | Pretty print C++ virtual function tables. The default is off. |
4853 | ||
4854 | @item set print vtbl off | |
4855 | Do not pretty print C++ virtual function tables. | |
4856 | ||
70b88761 | 4857 | @kindex show print vtbl |
af215b1a | 4858 | @item show print vtbl |
70b88761 | 4859 | Show whether C++ virtual function tables are pretty printed, or not. |
70b88761 | 4860 | @end table |
1d7c3357 | 4861 | @end ifclear |
70b88761 | 4862 | |
4eb4cf57 | 4863 | @node Value History |
93928b60 | 4864 | @section Value history |
70b88761 RP |
4865 | |
4866 | @cindex value history | |
af215b1a VM |
4867 | Values printed by the @code{print} command are saved in the @value{GDBN} |
4868 | @dfn{value history}. This allows you to refer to them in other expressions. | |
4869 | Values are kept until the symbol table is re-read or discarded | |
4870 | (for example with the @code{file} or @code{symbol-file} commands). | |
4871 | When the symbol table changes, the value history is discarded, | |
4872 | since the values may contain pointers back to the types defined in the | |
4873 | symbol table. | |
70b88761 RP |
4874 | |
4875 | @cindex @code{$} | |
4876 | @cindex @code{$$} | |
4877 | @cindex history number | |
6b51acad RP |
4878 | The values printed are given @dfn{history numbers} by which you can |
4879 | refer to them. These are successive integers starting with one. | |
4880 | @code{print} shows you the history number assigned to a value by | |
4881 | printing @samp{$@var{num} = } before the value; here @var{num} is the | |
4882 | history number. | |
70b88761 RP |
4883 | |
4884 | To refer to any previous value, use @samp{$} followed by the value's | |
4885 | history number. The way @code{print} labels its output is designed to | |
4886 | remind you of this. Just @code{$} refers to the most recent value in | |
4887 | the history, and @code{$$} refers to the value before that. | |
4888 | @code{$$@var{n}} refers to the @var{n}th value from the end; @code{$$2} | |
4889 | is the value just prior to @code{$$}, @code{$$1} is equivalent to | |
4890 | @code{$$}, and @code{$$0} is equivalent to @code{$}. | |
4891 | ||
4892 | For example, suppose you have just printed a pointer to a structure and | |
4893 | want to see the contents of the structure. It suffices to type | |
4894 | ||
4895 | @example | |
4896 | p *$ | |
4897 | @end example | |
4898 | ||
4899 | If you have a chain of structures where the component @code{next} points | |
4900 | to the next one, you can print the contents of the next one with this: | |
4901 | ||
4902 | @example | |
4903 | p *$.next | |
4904 | @end example | |
4905 | ||
4906 | @noindent | |
4907 | You can print successive links in the chain by repeating this | |
4908 | command---which you can do by just typing @key{RET}. | |
4909 | ||
4910 | Note that the history records values, not expressions. If the value of | |
4911 | @code{x} is 4 and you type these commands: | |
4912 | ||
4913 | @example | |
4914 | print x | |
4915 | set x=5 | |
4916 | @end example | |
4917 | ||
4918 | @noindent | |
4919 | then the value recorded in the value history by the @code{print} command | |
4920 | remains 4 even though the value of @code{x} has changed. | |
4921 | ||
4922 | @table @code | |
4923 | @kindex show values | |
4924 | @item show values | |
4925 | Print the last ten values in the value history, with their item numbers. | |
4926 | This is like @samp{p@ $$9} repeated ten times, except that @code{show | |
4927 | values} does not change the history. | |
4928 | ||
4929 | @item show values @var{n} | |
4930 | Print ten history values centered on history item number @var{n}. | |
4931 | ||
4932 | @item show values + | |
4933 | Print ten history values just after the values last printed. If no more | |
af215b1a | 4934 | values are available, @code{show values +} produces no display. |
70b88761 RP |
4935 | @end table |
4936 | ||
4937 | Pressing @key{RET} to repeat @code{show values @var{n}} has exactly the | |
e251e767 | 4938 | same effect as @samp{show values +}. |
70b88761 | 4939 | |
4eb4cf57 | 4940 | @node Convenience Vars |
93928b60 | 4941 | @section Convenience variables |
70b88761 RP |
4942 | |
4943 | @cindex convenience variables | |
18fae2a8 RP |
4944 | @value{GDBN} provides @dfn{convenience variables} that you can use within |
4945 | @value{GDBN} to hold on to a value and refer to it later. These variables | |
4946 | exist entirely within @value{GDBN}; they are not part of your program, and | |
70b88761 | 4947 | setting a convenience variable has no direct effect on further execution |
1041a570 | 4948 | of your program. That is why you can use them freely. |
70b88761 RP |
4949 | |
4950 | Convenience variables are prefixed with @samp{$}. Any name preceded by | |
4951 | @samp{$} can be used for a convenience variable, unless it is one of | |
4952 | the predefined machine-specific register names (@pxref{Registers}). | |
4953 | (Value history references, in contrast, are @emph{numbers} preceded | |
93928b60 | 4954 | by @samp{$}. @xref{Value History, ,Value history}.) |
70b88761 RP |
4955 | |
4956 | You can save a value in a convenience variable with an assignment | |
ed447b95 RP |
4957 | expression, just as you would set a variable in your program. |
4958 | For example: | |
70b88761 RP |
4959 | |
4960 | @example | |
4961 | set $foo = *object_ptr | |
4962 | @end example | |
4963 | ||
4964 | @noindent | |
4965 | would save in @code{$foo} the value contained in the object pointed to by | |
4966 | @code{object_ptr}. | |
4967 | ||
6b51acad RP |
4968 | Using a convenience variable for the first time creates it, but its |
4969 | value is @code{void} until you assign a new value. You can alter the | |
4970 | value with another assignment at any time. | |
70b88761 RP |
4971 | |
4972 | Convenience variables have no fixed types. You can assign a convenience | |
4973 | variable any type of value, including structures and arrays, even if | |
4974 | that variable already has a value of a different type. The convenience | |
4975 | variable, when used as an expression, has the type of its current value. | |
4976 | ||
4977 | @table @code | |
70b88761 | 4978 | @kindex show convenience |
af215b1a | 4979 | @item show convenience |
70b88761 RP |
4980 | Print a list of convenience variables used so far, and their values. |
4981 | Abbreviated @code{show con}. | |
4982 | @end table | |
4983 | ||
4984 | One of the ways to use a convenience variable is as a counter to be | |
4985 | incremented or a pointer to be advanced. For example, to print | |
4986 | a field from successive elements of an array of structures: | |
4987 | ||
18fae2a8 | 4988 | @example |
70b88761 RP |
4989 | set $i = 0 |
4990 | print bar[$i++]->contents | |
18fae2a8 | 4991 | @end example |
70b88761 | 4992 | |
af215b1a VM |
4993 | @noindent Repeat that command by typing @key{RET}. |
4994 | ||
18fae2a8 | 4995 | Some convenience variables are created automatically by @value{GDBN} and given |
70b88761 RP |
4996 | values likely to be useful. |
4997 | ||
4998 | @table @code | |
c338a2fd | 4999 | @kindex $_ |
af215b1a | 5000 | @item $_ |
70b88761 | 5001 | The variable @code{$_} is automatically set by the @code{x} command to |
93928b60 | 5002 | the last address examined (@pxref{Memory, ,Examining memory}). Other |
29a2b744 RP |
5003 | commands which provide a default address for @code{x} to examine also |
5004 | set @code{$_} to that address; these commands include @code{info line} | |
5005 | and @code{info breakpoint}. The type of @code{$_} is @code{void *} | |
5006 | except when set by the @code{x} command, in which case it is a pointer | |
5007 | to the type of @code{$__}. | |
70b88761 | 5008 | |
c338a2fd | 5009 | @kindex $__ |
af215b1a | 5010 | @item $__ |
70b88761 | 5011 | The variable @code{$__} is automatically set by the @code{x} command |
c2bbbb22 RP |
5012 | to the value found in the last address examined. Its type is chosen |
5013 | to match the format in which the data was printed. | |
f94cadf9 SS |
5014 | |
5015 | @item $_exitcode | |
5016 | @kindex $_exitcode | |
5017 | The variable @code{$_exitcode} is automatically set to the exit code when | |
5018 | the program being debugged terminates. | |
70b88761 RP |
5019 | @end table |
5020 | ||
4eb4cf57 | 5021 | @node Registers |
70b88761 RP |
5022 | @section Registers |
5023 | ||
5024 | @cindex registers | |
b80282d5 | 5025 | You can refer to machine register contents, in expressions, as variables |
70b88761 RP |
5026 | with names starting with @samp{$}. The names of registers are different |
5027 | for each machine; use @code{info registers} to see the names used on | |
e251e767 | 5028 | your machine. |
70b88761 RP |
5029 | |
5030 | @table @code | |
70b88761 | 5031 | @kindex info registers |
af215b1a | 5032 | @item info registers |
b80282d5 RP |
5033 | Print the names and values of all registers except floating-point |
5034 | registers (in the selected stack frame). | |
5035 | ||
b80282d5 RP |
5036 | @kindex info all-registers |
5037 | @cindex floating point registers | |
af215b1a | 5038 | @item info all-registers |
b80282d5 RP |
5039 | Print the names and values of all registers, including floating-point |
5040 | registers. | |
70b88761 | 5041 | |
4eb4cf57 | 5042 | @item info registers @var{regname} @dots{} |
af215b1a VM |
5043 | Print the @dfn{relativized} value of each specified register @var{regname}. |
5044 | As discussed in detail below, register values are normally relative to | |
5045 | the selected stack frame. @var{regname} may be any register name valid on | |
5046 | the machine you are using, with or without the initial @samp{$}. | |
70b88761 RP |
5047 | @end table |
5048 | ||
18fae2a8 | 5049 | @value{GDBN} has four ``standard'' register names that are available (in |
29a2b744 | 5050 | expressions) on most machines---whenever they do not conflict with an |
09267865 RP |
5051 | architecture's canonical mnemonics for registers. The register names |
5052 | @code{$pc} and @code{$sp} are used for the program counter register and | |
5053 | the stack pointer. @code{$fp} is used for a register that contains a | |
5054 | pointer to the current stack frame, and @code{$ps} is used for a | |
5055 | register that contains the processor status. For example, | |
70b88761 | 5056 | you could print the program counter in hex with |
1041a570 | 5057 | |
70b88761 RP |
5058 | @example |
5059 | p/x $pc | |
5060 | @end example | |
5061 | ||
5062 | @noindent | |
5063 | or print the instruction to be executed next with | |
1041a570 | 5064 | |
70b88761 RP |
5065 | @example |
5066 | x/i $pc | |
5067 | @end example | |
5068 | ||
5069 | @noindent | |
ed447b95 | 5070 | or add four to the stack pointer@footnote{This is a way of removing |
29a2b744 RP |
5071 | one word from the stack, on machines where stacks grow downward in |
5072 | memory (most machines, nowadays). This assumes that the innermost | |
5073 | stack frame is selected; setting @code{$sp} is not allowed when other | |
5074 | stack frames are selected. To pop entire frames off the stack, | |
5075 | regardless of machine architecture, use @code{return}; | |
93928b60 | 5076 | @pxref{Returning, ,Returning from a function}.} with |
1041a570 | 5077 | |
70b88761 RP |
5078 | @example |
5079 | set $sp += 4 | |
5080 | @end example | |
5081 | ||
09267865 RP |
5082 | Whenever possible, these four standard register names are available on |
5083 | your machine even though the machine has different canonical mnemonics, | |
5084 | so long as there is no conflict. The @code{info registers} command | |
5085 | shows the canonical names. For example, on the SPARC, @code{info | |
70b88761 RP |
5086 | registers} displays the processor status register as @code{$psr} but you |
5087 | can also refer to it as @code{$ps}. | |
5088 | ||
18fae2a8 | 5089 | @value{GDBN} always considers the contents of an ordinary register as an |
70b88761 RP |
5090 | integer when the register is examined in this way. Some machines have |
5091 | special registers which can hold nothing but floating point; these | |
5092 | registers are considered to have floating point values. There is no way | |
5093 | to refer to the contents of an ordinary register as floating point value | |
5094 | (although you can @emph{print} it as a floating point value with | |
5095 | @samp{print/f $@var{regname}}). | |
5096 | ||
5097 | Some registers have distinct ``raw'' and ``virtual'' data formats. This | |
5098 | means that the data format in which the register contents are saved by | |
5099 | the operating system is not the same one that your program normally | |
5100 | sees. For example, the registers of the 68881 floating point | |
5101 | coprocessor are always saved in ``extended'' (raw) format, but all C | |
5102 | programs expect to work with ``double'' (virtual) format. In such | |
af215b1a VM |
5103 | cases, @value{GDBN} normally works with the virtual format only (the format |
5104 | that makes sense for your program), but the @code{info registers} command | |
70b88761 RP |
5105 | prints the data in both formats. |
5106 | ||
5107 | Normally, register values are relative to the selected stack frame | |
93928b60 | 5108 | (@pxref{Selection, ,Selecting a frame}). This means that you get the |
29a2b744 RP |
5109 | value that the register would contain if all stack frames farther in |
5110 | were exited and their saved registers restored. In order to see the | |
5111 | true contents of hardware registers, you must select the innermost | |
5112 | frame (with @samp{frame 0}). | |
70b88761 | 5113 | |
18fae2a8 | 5114 | However, @value{GDBN} must deduce where registers are saved, from the machine |
70b88761 | 5115 | code generated by your compiler. If some registers are not saved, or if |
18fae2a8 | 5116 | @value{GDBN} is unable to locate the saved registers, the selected stack |
9a27b06e | 5117 | frame makes no difference. |
70b88761 | 5118 | |
a64a6c2b | 5119 | @ifset AMD29K |
03a77779 | 5120 | @table @code |
d8a68b28 | 5121 | @kindex set rstack_high_address |
03a77779 RP |
5122 | @cindex AMD 29K register stack |
5123 | @cindex register stack, AMD29K | |
af215b1a | 5124 | @item set rstack_high_address @var{address} |
03a77779 | 5125 | On AMD 29000 family processors, registers are saved in a separate |
18fae2a8 RP |
5126 | ``register stack''. There is no way for @value{GDBN} to determine the extent |
5127 | of this stack. Normally, @value{GDBN} just assumes that the stack is ``large | |
5128 | enough''. This may result in @value{GDBN} referencing memory locations that | |
93918348 | 5129 | do not exist. If necessary, you can get around this problem by |
03a77779 RP |
5130 | specifying the ending address of the register stack with the @code{set |
5131 | rstack_high_address} command. The argument should be an address, which | |
9a27b06e | 5132 | you probably want to precede with @samp{0x} to specify in |
03a77779 | 5133 | hexadecimal. |
d8a68b28 | 5134 | |
d8a68b28 | 5135 | @kindex show rstack_high_address |
af215b1a | 5136 | @item show rstack_high_address |
03a77779 RP |
5137 | Display the current limit of the register stack, on AMD 29000 family |
5138 | processors. | |
5139 | @end table | |
18fae2a8 | 5140 | @end ifset |
d8a68b28 | 5141 | |
a64a6c2b | 5142 | @ifclear HAVE-FLOAT |
4eb4cf57 | 5143 | @node Floating Point Hardware |
93928b60 | 5144 | @section Floating point hardware |
70b88761 | 5145 | @cindex floating point |
1041a570 | 5146 | |
f886dc0f | 5147 | Depending on the configuration, @value{GDBN} may be able to give |
70b88761 RP |
5148 | you more information about the status of the floating point hardware. |
5149 | ||
5150 | @table @code | |
70b88761 | 5151 | @kindex info float |
af215b1a | 5152 | @item info float |
8c69096b | 5153 | Display hardware-dependent information about the floating |
70b88761 | 5154 | point unit. The exact contents and layout vary depending on the |
af215b1a VM |
5155 | floating point chip. Currently, @samp{info float} is supported on |
5156 | the ARM and x86 machines. | |
70b88761 | 5157 | @end table |
18fae2a8 | 5158 | @end ifclear |
70b88761 | 5159 | |
18fae2a8 | 5160 | @ifclear CONLY |
4eb4cf57 | 5161 | @node Languages |
18fae2a8 | 5162 | @chapter Using @value{GDBN} with Different Languages |
c2bbbb22 RP |
5163 | @cindex languages |
5164 | ||
09934a2b | 5165 | @ifset MOD2 |
c2bbbb22 RP |
5166 | Although programming languages generally have common aspects, they are |
5167 | rarely expressed in the same manner. For instance, in ANSI C, | |
5168 | dereferencing a pointer @code{p} is accomplished by @code{*p}, but in | |
5169 | Modula-2, it is accomplished by @code{p^}. Values can also be | |
af215b1a VM |
5170 | represented (and displayed) differently. Hex numbers in C appear as |
5171 | @samp{0x1ae}, while in Modula-2 they appear as @samp{1AEH}. | |
09934a2b | 5172 | @end ifset |
c2bbbb22 RP |
5173 | |
5174 | @cindex working language | |
18fae2a8 | 5175 | Language-specific information is built into @value{GDBN} for some languages, |
29a2b744 | 5176 | allowing you to express operations like the above in your program's |
18fae2a8 | 5177 | native language, and allowing @value{GDBN} to output values in a manner |
29a2b744 | 5178 | consistent with the syntax of your program's native language. The |
af215b1a VM |
5179 | language you use to build expressions is called the @dfn{working |
5180 | language}. | |
c2bbbb22 RP |
5181 | |
5182 | @menu | |
5183 | * Setting:: Switching between source languages | |
5184 | * Show:: Displaying the language | |
09934a2b | 5185 | @ifset MOD2 |
ed447b95 | 5186 | * Checks:: Type and range checks |
09934a2b | 5187 | @end ifset |
da374d80 | 5188 | |
c2bbbb22 RP |
5189 | * Support:: Supported languages |
5190 | @end menu | |
5191 | ||
4eb4cf57 | 5192 | @node Setting |
c2bbbb22 RP |
5193 | @section Switching between source languages |
5194 | ||
18fae2a8 | 5195 | There are two ways to control the working language---either have @value{GDBN} |
c2bbbb22 | 5196 | set it automatically, or select it manually yourself. You can use the |
18fae2a8 | 5197 | @code{set language} command for either purpose. On startup, @value{GDBN} |
d05baf08 JK |
5198 | defaults to setting the language automatically. The working language is |
5199 | used to determine how expressions you type are interpreted, how values | |
5200 | are printed, etc. | |
5201 | ||
af215b1a | 5202 | In addition to the working language, every source file that |
d05baf08 JK |
5203 | @value{GDBN} knows about has its own working language. For some object |
5204 | file formats, the compiler might indicate which language a particular | |
af215b1a | 5205 | source file is in. However, most of the time @value{GDBN} infers the |
d05baf08 JK |
5206 | language from the name of the file. The language of a source file |
5207 | controls whether C++ names are demangled---this way @code{backtrace} can | |
5208 | show each frame appropriately for its own language. There is no way to | |
af215b1a VM |
5209 | set the language of a source file from within @value{GDBN}. |
5210 | ||
5211 | This is most commonly a problem when you use a program, such | |
5212 | as @code{cfront} or @code{f2c}, that generates C but is written in | |
5213 | another language. In that case, make the | |
d05baf08 | 5214 | program use @code{#line} directives in its C output; that way |
af215b1a VM |
5215 | @value{GDBN} will know the correct language of the source code of the original |
5216 | program, and will display that source code, not the generated C code. | |
c2bbbb22 RP |
5217 | |
5218 | @menu | |
d05baf08 | 5219 | * Filenames:: Filename extensions and languages. |
c2bbbb22 | 5220 | * Manually:: Setting the working language manually |
18fae2a8 | 5221 | * Automatically:: Having @value{GDBN} infer the source language |
c2bbbb22 RP |
5222 | @end menu |
5223 | ||
d05baf08 JK |
5224 | @node Filenames |
5225 | @subsection List of filename extensions and languages | |
5226 | ||
5227 | If a source file name ends in one of the following extensions, then | |
5228 | @value{GDBN} infers that its language is the one indicated. | |
5229 | ||
5230 | @table @file | |
5231 | @ifset MOD2 | |
5232 | @item .mod | |
5233 | Modula-2 source file | |
5234 | @end ifset | |
5235 | ||
5236 | @item .c | |
5237 | C source file | |
5238 | ||
5239 | @item .C | |
5240 | @itemx .cc | |
5241 | @itemx .cxx | |
5242 | @itemx .cpp | |
5243 | @itemx .cp | |
5244 | @itemx .c++ | |
5245 | C++ source file | |
5246 | ||
5247 | @item .ch | |
5248 | @itemx .c186 | |
5249 | @itemx .c286 | |
5250 | CHILL source file. | |
5251 | ||
5252 | @item .s | |
5253 | @itemx .S | |
5254 | Assembler source file. This actually behaves almost like C, but | |
5255 | @value{GDBN} does not skip over function prologues when stepping. | |
5256 | @end table | |
5257 | ||
4eb4cf57 | 5258 | @node Manually |
c2bbbb22 RP |
5259 | @subsection Setting the working language |
5260 | ||
ed447b95 RP |
5261 | If you allow @value{GDBN} to set the language automatically, |
5262 | expressions are interpreted the same way in your debugging session and | |
5263 | your program. | |
5264 | ||
c2bbbb22 | 5265 | @kindex set language |
ed447b95 RP |
5266 | If you wish, you may set the language manually. To do this, issue the |
5267 | command @samp{set language @var{lang}}, where @var{lang} is the name of | |
09934a2b RP |
5268 | a language, such as |
5269 | @ifclear MOD2 | |
5270 | @code{c}. | |
5271 | @end ifclear | |
5272 | @ifset MOD2 | |
5273 | @code{c} or @code{modula-2}. | |
5274 | @end ifset | |
5275 | For a list of the supported languages, type @samp{set language}. | |
c2bbbb22 | 5276 | |
09934a2b | 5277 | @ifset MOD2 |
18fae2a8 | 5278 | Setting the language manually prevents @value{GDBN} from updating the working |
c2bbbb22 RP |
5279 | language automatically. This can lead to confusion if you try |
5280 | to debug a program when the working language is not the same as the | |
5281 | source language, when an expression is acceptable to both | |
5282 | languages---but means different things. For instance, if the current | |
18fae2a8 | 5283 | source file were written in C, and @value{GDBN} was parsing Modula-2, a |
c2bbbb22 RP |
5284 | command such as: |
5285 | ||
5286 | @example | |
5287 | print a = b + c | |
5288 | @end example | |
5289 | ||
5290 | @noindent | |
5291 | might not have the effect you intended. In C, this means to add | |
5292 | @code{b} and @code{c} and place the result in @code{a}. The result | |
5293 | printed would be the value of @code{a}. In Modula-2, this means to compare | |
5294 | @code{a} to the result of @code{b+c}, yielding a @code{BOOLEAN} value. | |
09934a2b | 5295 | @end ifset |
c2bbbb22 | 5296 | |
4eb4cf57 | 5297 | @node Automatically |
18fae2a8 | 5298 | @subsection Having @value{GDBN} infer the source language |
c2bbbb22 | 5299 | |
d05baf08 JK |
5300 | To have @value{GDBN} set the working language automatically, use |
5301 | @samp{set language local} or @samp{set language auto}. @value{GDBN} | |
5302 | then infers the working language. That is, when your program stops in a | |
5303 | frame (usually by encountering a breakpoint), @value{GDBN} sets the | |
5304 | working language to the language recorded for the function in that | |
5305 | frame. If the language for a frame is unknown (that is, if the function | |
5306 | or block corresponding to the frame was defined in a source file that | |
5307 | does not have a recognized extension), the current working language is | |
5308 | not changed, and @value{GDBN} issues a warning. | |
c2bbbb22 RP |
5309 | |
5310 | This may not seem necessary for most programs, which are written | |
5311 | entirely in one source language. However, program modules and libraries | |
5312 | written in one source language can be used by a main program written in | |
5313 | a different source language. Using @samp{set language auto} in this | |
5314 | case frees you from having to set the working language manually. | |
5315 | ||
4eb4cf57 | 5316 | @node Show |
c2bbbb22 RP |
5317 | @section Displaying the language |
5318 | ||
9a27b06e | 5319 | The following commands help you find out which language is the |
c2bbbb22 RP |
5320 | working language, and also what language source files were written in. |
5321 | ||
5322 | @kindex show language | |
5323 | @kindex info frame | |
5324 | @kindex info source | |
5325 | @table @code | |
5326 | @item show language | |
5327 | Display the current working language. This is the | |
5328 | language you can use with commands such as @code{print} to | |
29a2b744 | 5329 | build and compute expressions that may involve variables in your program. |
c2bbbb22 RP |
5330 | |
5331 | @item info frame | |
af215b1a VM |
5332 | Display the source language for this frame. This language becomes the |
5333 | working language if you use an identifier from this frame. | |
5334 | @xref{Frame Info, ,Information about a frame}, to identify the other | |
5335 | information listed here. | |
c2bbbb22 RP |
5336 | |
5337 | @item info source | |
af215b1a VM |
5338 | Display the source language of this source file. |
5339 | @xref{Symbols, ,Examining the Symbol Table}, to identify the other | |
5340 | information listed here. | |
c2bbbb22 RP |
5341 | @end table |
5342 | ||
09934a2b | 5343 | @ifset MOD2 |
4eb4cf57 | 5344 | @node Checks |
93928b60 | 5345 | @section Type and range checking |
c2bbbb22 RP |
5346 | |
5347 | @quotation | |
18fae2a8 | 5348 | @emph{Warning:} In this release, the @value{GDBN} commands for type and range |
c2bbbb22 RP |
5349 | checking are included, but they do not yet have any effect. This |
5350 | section documents the intended facilities. | |
5351 | @end quotation | |
5352 | @c FIXME remove warning when type/range code added | |
5353 | ||
5354 | Some languages are designed to guard you against making seemingly common | |
5355 | errors through a series of compile- and run-time checks. These include | |
5356 | checking the type of arguments to functions and operators, and making | |
5357 | sure mathematical overflows are caught at run time. Checks such as | |
5358 | these help to ensure a program's correctness once it has been compiled | |
5359 | by eliminating type mismatches, and providing active checks for range | |
29a2b744 | 5360 | errors when your program is running. |
c2bbbb22 | 5361 | |
18fae2a8 | 5362 | @value{GDBN} can check for conditions like the above if you wish. |
9a27b06e | 5363 | Although @value{GDBN} does not check the statements in your program, it |
18fae2a8 | 5364 | can check expressions entered directly into @value{GDBN} for evaluation via |
1041a570 | 5365 | the @code{print} command, for example. As with the working language, |
18fae2a8 | 5366 | @value{GDBN} can also decide whether or not to check automatically based on |
93928b60 | 5367 | your program's source language. @xref{Support, ,Supported languages}, |
1041a570 | 5368 | for the default settings of supported languages. |
c2bbbb22 RP |
5369 | |
5370 | @menu | |
5371 | * Type Checking:: An overview of type checking | |
5372 | * Range Checking:: An overview of range checking | |
5373 | @end menu | |
5374 | ||
5375 | @cindex type checking | |
5376 | @cindex checks, type | |
4eb4cf57 | 5377 | @node Type Checking |
c2bbbb22 RP |
5378 | @subsection An overview of type checking |
5379 | ||
5380 | Some languages, such as Modula-2, are strongly typed, meaning that the | |
5381 | arguments to operators and functions have to be of the correct type, | |
5382 | otherwise an error occurs. These checks prevent type mismatch | |
5383 | errors from ever causing any run-time problems. For example, | |
5384 | ||
af215b1a | 5385 | @smallexample |
c2bbbb22 | 5386 | 1 + 2 @result{} 3 |
1041a570 | 5387 | @exdent but |
c2bbbb22 | 5388 | @error{} 1 + 2.3 |
af215b1a | 5389 | @end smallexample |
c2bbbb22 RP |
5390 | |
5391 | The second example fails because the @code{CARDINAL} 1 is not | |
5392 | type-compatible with the @code{REAL} 2.3. | |
5393 | ||
af215b1a VM |
5394 | For the expressions you use in @value{GDBN} commands, you can tell the |
5395 | @value{GDBN} type checker to skip checking; | |
5396 | to treat any mismatches as errors and abandon the expression; | |
5397 | or to only issue warnings when type mismatches occur, | |
5398 | but evaluate the expression anyway. When you choose the last of | |
18fae2a8 | 5399 | these, @value{GDBN} evaluates expressions like the second example above, but |
c2bbbb22 RP |
5400 | also issues a warning. |
5401 | ||
af215b1a VM |
5402 | Even if you turn type checking off, there may be other reasons |
5403 | related to type that prevent @value{GDBN} from evaluating an expression. | |
5404 | For instance, @value{GDBN} does not know how to add an @code{int} and | |
5405 | a @code{struct foo}. These particular type errors have nothing to do | |
5406 | with the language in use, and usually arise from expressions, such as | |
5407 | the one described above, which make little sense to evaluate anyway. | |
c2bbbb22 RP |
5408 | |
5409 | Each language defines to what degree it is strict about type. For | |
5410 | instance, both Modula-2 and C require the arguments to arithmetical | |
5411 | operators to be numbers. In C, enumerated types and pointers can be | |
5412 | represented as numbers, so that they are valid arguments to mathematical | |
93928b60 | 5413 | operators. @xref{Support, ,Supported languages}, for further |
c2bbbb22 RP |
5414 | details on specific languages. |
5415 | ||
18fae2a8 | 5416 | @value{GDBN} provides some additional commands for controlling the type checker: |
c2bbbb22 RP |
5417 | |
5418 | @kindex set check | |
5419 | @kindex set check type | |
5420 | @kindex show check type | |
5421 | @table @code | |
5422 | @item set check type auto | |
e251e767 | 5423 | Set type checking on or off based on the current working language. |
93928b60 | 5424 | @xref{Support, ,Supported languages}, for the default settings for |
c2bbbb22 RP |
5425 | each language. |
5426 | ||
5427 | @item set check type on | |
5428 | @itemx set check type off | |
5429 | Set type checking on or off, overriding the default setting for the | |
5430 | current working language. Issue a warning if the setting does not | |
93918348 | 5431 | match the language default. If any type mismatches occur in |
18fae2a8 | 5432 | evaluating an expression while typechecking is on, @value{GDBN} prints a |
c2bbbb22 RP |
5433 | message and aborts evaluation of the expression. |
5434 | ||
5435 | @item set check type warn | |
5436 | Cause the type checker to issue warnings, but to always attempt to | |
5437 | evaluate the expression. Evaluating the expression may still | |
18fae2a8 | 5438 | be impossible for other reasons. For example, @value{GDBN} cannot add |
c2bbbb22 RP |
5439 | numbers and structures. |
5440 | ||
5441 | @item show type | |
af215b1a VM |
5442 | Show the current setting of the type checker, and whether or not @value{GDBN} |
5443 | is setting it automatically. | |
c2bbbb22 RP |
5444 | @end table |
5445 | ||
5446 | @cindex range checking | |
5447 | @cindex checks, range | |
4eb4cf57 | 5448 | @node Range Checking |
ed447b95 | 5449 | @subsection An overview of range checking |
c2bbbb22 RP |
5450 | |
5451 | In some languages (such as Modula-2), it is an error to exceed the | |
5452 | bounds of a type; this is enforced with run-time checks. Such range | |
5453 | checking is meant to ensure program correctness by making sure | |
5454 | computations do not overflow, or indices on an array element access do | |
5455 | not exceed the bounds of the array. | |
5456 | ||
ed447b95 RP |
5457 | For expressions you use in @value{GDBN} commands, you can tell |
5458 | @value{GDBN} to treat range errors in one of three ways: ignore them, | |
5459 | always treat them as errors and abandon the expression, or issue | |
5460 | warnings but evaluate the expression anyway. | |
c2bbbb22 RP |
5461 | |
5462 | A range error can result from numerical overflow, from exceeding an | |
ed447b95 | 5463 | array index bound, or when you type a constant that is not a member |
c2bbbb22 RP |
5464 | of any type. Some languages, however, do not treat overflows as an |
5465 | error. In many implementations of C, mathematical overflow causes the | |
5466 | result to ``wrap around'' to lower values---for example, if @var{m} is | |
5467 | the largest integer value, and @var{s} is the smallest, then | |
1041a570 | 5468 | |
c2bbbb22 RP |
5469 | @example |
5470 | @var{m} + 1 @result{} @var{s} | |
5471 | @end example | |
5472 | ||
5473 | This, too, is specific to individual languages, and in some cases | |
1041a570 | 5474 | specific to individual compilers or machines. @xref{Support, , |
93928b60 | 5475 | Supported languages}, for further details on specific languages. |
c2bbbb22 | 5476 | |
18fae2a8 | 5477 | @value{GDBN} provides some additional commands for controlling the range checker: |
c2bbbb22 RP |
5478 | |
5479 | @kindex set check | |
5480 | @kindex set check range | |
5481 | @kindex show check range | |
5482 | @table @code | |
5483 | @item set check range auto | |
e251e767 | 5484 | Set range checking on or off based on the current working language. |
93928b60 | 5485 | @xref{Support, ,Supported languages}, for the default settings for |
c2bbbb22 RP |
5486 | each language. |
5487 | ||
5488 | @item set check range on | |
5489 | @itemx set check range off | |
5490 | Set range checking on or off, overriding the default setting for the | |
5491 | current working language. A warning is issued if the setting does not | |
93918348 | 5492 | match the language default. If a range error occurs, then a message |
c2bbbb22 RP |
5493 | is printed and evaluation of the expression is aborted. |
5494 | ||
5495 | @item set check range warn | |
18fae2a8 | 5496 | Output messages when the @value{GDBN} range checker detects a range error, |
c2bbbb22 RP |
5497 | but attempt to evaluate the expression anyway. Evaluating the |
5498 | expression may still be impossible for other reasons, such as accessing | |
6b51acad | 5499 | memory that the process does not own (a typical example from many Unix |
c2bbbb22 RP |
5500 | systems). |
5501 | ||
5502 | @item show range | |
e251e767 | 5503 | Show the current setting of the range checker, and whether or not it is |
18fae2a8 | 5504 | being set automatically by @value{GDBN}. |
c2bbbb22 | 5505 | @end table |
09934a2b | 5506 | @end ifset |
c2bbbb22 | 5507 | |
4eb4cf57 | 5508 | @node Support |
93928b60 | 5509 | @section Supported languages |
c2bbbb22 | 5510 | |
09934a2b RP |
5511 | @ifset MOD2 |
5512 | @value{GDBN} 4 supports C, C++, and Modula-2. | |
5513 | @end ifset | |
5514 | @ifclear MOD2 | |
5515 | @value{GDBN} 4 supports C, and C++. | |
5516 | @end ifclear | |
5517 | Some @value{GDBN} features may be used in expressions regardless of the | |
5518 | language you use: the @value{GDBN} @code{@@} and @code{::} operators, | |
5519 | and the @samp{@{type@}addr} construct (@pxref{Expressions, | |
5520 | ,Expressions}) can be used with the constructs of any supported | |
5521 | language. | |
5522 | ||
5523 | The following sections detail to what degree each source language is | |
5524 | supported by @value{GDBN}. These sections are not meant to be language | |
5525 | tutorials or references, but serve only as a reference guide to what the | |
9a27b06e | 5526 | @value{GDBN} expression parser accepts, and what input and output |
09934a2b RP |
5527 | formats should look like for different languages. There are many good |
5528 | books written on each of these languages; please look to these for a | |
5529 | language reference or tutorial. | |
5530 | ||
5531 | @ifset MOD2 | |
c2bbbb22 RP |
5532 | @menu |
5533 | * C:: C and C++ | |
5534 | * Modula-2:: Modula-2 | |
5535 | @end menu | |
5536 | ||
4eb4cf57 | 5537 | @node C |
c2bbbb22 RP |
5538 | @subsection C and C++ |
5539 | @cindex C and C++ | |
c2bbbb22 | 5540 | @cindex expressions in C or C++ |
0f153e74 | 5541 | |
18fae2a8 | 5542 | Since C and C++ are so closely related, many features of @value{GDBN} apply |
af215b1a | 5543 | to both languages. Whenever this is the case, we discuss those languages |
5a2c1d85 | 5544 | together. |
09934a2b RP |
5545 | @end ifset |
5546 | @ifclear MOD2 | |
5547 | @c Cancel this below, under same condition, at end of this chapter! | |
6370267a | 5548 | @raisesections |
09934a2b | 5549 | @end ifclear |
b80282d5 RP |
5550 | |
5551 | @cindex C++ | |
5552 | @kindex g++ | |
af215b1a VM |
5553 | @cindex @sc{gnu} C++ |
5554 | The C++ debugging facilities are jointly implemented by the @sc{gnu} C++ | |
22b5dba5 | 5555 | compiler and @value{GDBN}. Therefore, to debug your C++ code |
af215b1a | 5556 | effectively, you must compile your C++ programs with the @sc{gnu} C++ |
22b5dba5 RP |
5557 | compiler, @code{g++}. |
5558 | ||
5559 | For best results when debugging C++ programs, use the stabs debugging | |
5560 | format. You can select that format explicitly with the @code{g++} | |
5561 | command-line options @samp{-gstabs} or @samp{-gstabs+}. See | |
af215b1a VM |
5562 | @ref{Debugging Options,,Options for Debugging Your Program or @sc{gnu} CC, |
5563 | gcc.info, Using @sc{gnu} CC}, for more information. | |
18fae2a8 RP |
5564 | @end ifclear |
5565 | @ifset CONLY | |
0f153e74 RP |
5566 | @node C |
5567 | @chapter C Language Support | |
5568 | @cindex C language | |
5569 | @cindex expressions in C | |
5570 | ||
18fae2a8 RP |
5571 | Information specific to the C language is built into @value{GDBN} so that you |
5572 | can use C expressions while degugging. This also permits @value{GDBN} to | |
0f153e74 | 5573 | output values in a manner consistent with C conventions. |
c2bbbb22 | 5574 | |
0f153e74 | 5575 | @menu |
ed447b95 RP |
5576 | * C Operators:: C operators |
5577 | * C Constants:: C constants | |
18fae2a8 | 5578 | * Debugging C:: @value{GDBN} and C |
0f153e74 | 5579 | @end menu |
18fae2a8 RP |
5580 | @end ifset |
5581 | @ifclear CONLY | |
b80282d5 | 5582 | @menu |
ed447b95 RP |
5583 | * C Operators:: C and C++ operators |
5584 | * C Constants:: C and C++ constants | |
5585 | * Cplus expressions:: C++ expressions | |
c2bbbb22 | 5586 | * C Defaults:: Default settings for C and C++ |
09934a2b | 5587 | @ifset MOD2 |
ed447b95 | 5588 | * C Checks:: C and C++ type and range checks |
09934a2b | 5589 | @end ifset |
da374d80 | 5590 | |
18fae2a8 | 5591 | * Debugging C:: @value{GDBN} and C |
c2bbbb22 | 5592 | * Debugging C plus plus:: Special features for C++ |
b80282d5 | 5593 | @end menu |
18fae2a8 | 5594 | @end ifclear |
b80282d5 | 5595 | |
18fae2a8 | 5596 | @ifclear CONLY |
c2bbbb22 | 5597 | @cindex C and C++ operators |
4eb4cf57 | 5598 | @node C Operators |
93928b60 | 5599 | @subsubsection C and C++ operators |
18fae2a8 RP |
5600 | @end ifclear |
5601 | @ifset CONLY | |
0f153e74 RP |
5602 | @cindex C operators |
5603 | @node C Operators | |
93928b60 | 5604 | @section C operators |
18fae2a8 | 5605 | @end ifset |
c2bbbb22 RP |
5606 | |
5607 | Operators must be defined on values of specific types. For instance, | |
5608 | @code{+} is defined on numbers, but not on structures. Operators are | |
0f153e74 RP |
5609 | often defined on groups of types. |
5610 | ||
18fae2a8 | 5611 | @ifclear CONLY |
0f153e74 | 5612 | For the purposes of C and C++, the following definitions hold: |
18fae2a8 | 5613 | @end ifclear |
c2bbbb22 RP |
5614 | |
5615 | @itemize @bullet | |
e251e767 | 5616 | @item |
c2bbbb22 | 5617 | @emph{Integral types} include @code{int} with any of its storage-class |
9aa964da | 5618 | specifiers; @code{char}; and @code{enum}. |
c2bbbb22 RP |
5619 | |
5620 | @item | |
5621 | @emph{Floating-point types} include @code{float} and @code{double}. | |
5622 | ||
5623 | @item | |
5624 | @emph{Pointer types} include all types defined as @code{(@var{type} | |
5625 | *)}. | |
5626 | ||
e251e767 | 5627 | @item |
c2bbbb22 | 5628 | @emph{Scalar types} include all of the above. |
c2bbbb22 RP |
5629 | @end itemize |
5630 | ||
5631 | @noindent | |
5632 | The following operators are supported. They are listed here | |
5633 | in order of increasing precedence: | |
5634 | ||
5635 | @table @code | |
18fae2a8 | 5636 | @item , |
c2bbbb22 RP |
5637 | The comma or sequencing operator. Expressions in a comma-separated list |
5638 | are evaluated from left to right, with the result of the entire | |
5639 | expression being the last expression evaluated. | |
5640 | ||
5641 | @item = | |
5642 | Assignment. The value of an assignment expression is the value | |
5643 | assigned. Defined on scalar types. | |
5644 | ||
5645 | @item @var{op}= | |
1041a570 RP |
5646 | Used in an expression of the form @w{@code{@var{a} @var{op}= @var{b}}}, |
5647 | and translated to @w{@code{@var{a} = @var{a op b}}}. | |
5648 | @w{@code{@var{op}=}} and @code{=} have the same precendence. | |
5649 | @var{op} is any one of the operators @code{|}, @code{^}, @code{&}, | |
5650 | @code{<<}, @code{>>}, @code{+}, @code{-}, @code{*}, @code{/}, @code{%}. | |
c2bbbb22 RP |
5651 | |
5652 | @item ?: | |
5653 | The ternary operator. @code{@var{a} ? @var{b} : @var{c}} can be thought | |
5654 | of as: if @var{a} then @var{b} else @var{c}. @var{a} should be of an | |
5655 | integral type. | |
5656 | ||
5657 | @item || | |
1041a570 | 5658 | Logical @sc{or}. Defined on integral types. |
c2bbbb22 RP |
5659 | |
5660 | @item && | |
1041a570 | 5661 | Logical @sc{and}. Defined on integral types. |
c2bbbb22 RP |
5662 | |
5663 | @item | | |
1041a570 | 5664 | Bitwise @sc{or}. Defined on integral types. |
c2bbbb22 RP |
5665 | |
5666 | @item ^ | |
1041a570 | 5667 | Bitwise exclusive-@sc{or}. Defined on integral types. |
c2bbbb22 RP |
5668 | |
5669 | @item & | |
1041a570 | 5670 | Bitwise @sc{and}. Defined on integral types. |
c2bbbb22 RP |
5671 | |
5672 | @item ==@r{, }!= | |
5673 | Equality and inequality. Defined on scalar types. The value of these | |
5674 | expressions is 0 for false and non-zero for true. | |
5675 | ||
5676 | @item <@r{, }>@r{, }<=@r{, }>= | |
5677 | Less than, greater than, less than or equal, greater than or equal. | |
5678 | Defined on scalar types. The value of these expressions is 0 for false | |
5679 | and non-zero for true. | |
5680 | ||
5681 | @item <<@r{, }>> | |
18fae2a8 | 5682 | left shift, and right shift. Defined on integral types. |
c2bbbb22 | 5683 | |
e251e767 | 5684 | @item @@ |
18fae2a8 | 5685 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). |
c2bbbb22 RP |
5686 | |
5687 | @item +@r{, }- | |
5688 | Addition and subtraction. Defined on integral types, floating-point types and | |
e251e767 | 5689 | pointer types. |
c2bbbb22 RP |
5690 | |
5691 | @item *@r{, }/@r{, }% | |
5692 | Multiplication, division, and modulus. Multiplication and division are | |
5693 | defined on integral and floating-point types. Modulus is defined on | |
5694 | integral types. | |
5695 | ||
5696 | @item ++@r{, }-- | |
5697 | Increment and decrement. When appearing before a variable, the | |
5698 | operation is performed before the variable is used in an expression; | |
5699 | when appearing after it, the variable's value is used before the | |
5700 | operation takes place. | |
5701 | ||
5702 | @item * | |
5703 | Pointer dereferencing. Defined on pointer types. Same precedence as | |
5704 | @code{++}. | |
5705 | ||
5706 | @item & | |
5707 | Address operator. Defined on variables. Same precedence as @code{++}. | |
5708 | ||
18fae2a8 | 5709 | @ifclear CONLY |
93918348 | 5710 | For debugging C++, @value{GDBN} implements a use of @samp{&} beyond what is |
6ca72cc6 | 5711 | allowed in the C++ language itself: you can use @samp{&(&@var{ref})} |
7640fe71 | 5712 | (or, if you prefer, simply @samp{&&@var{ref}}) to examine the address |
6ca72cc6 RP |
5713 | where a C++ reference variable (declared with @samp{&@var{ref}}) is |
5714 | stored. | |
18fae2a8 | 5715 | @end ifclear |
6ca72cc6 | 5716 | |
c2bbbb22 RP |
5717 | @item - |
5718 | Negative. Defined on integral and floating-point types. Same | |
5719 | precedence as @code{++}. | |
5720 | ||
5721 | @item ! | |
5722 | Logical negation. Defined on integral types. Same precedence as | |
5723 | @code{++}. | |
5724 | ||
5725 | @item ~ | |
5726 | Bitwise complement operator. Defined on integral types. Same precedence as | |
5727 | @code{++}. | |
5728 | ||
18fae2a8 | 5729 | |
c2bbbb22 RP |
5730 | @item .@r{, }-> |
5731 | Structure member, and pointer-to-structure member. For convenience, | |
18fae2a8 | 5732 | @value{GDBN} regards the two as equivalent, choosing whether to dereference a |
e251e767 | 5733 | pointer based on the stored type information. |
9aa964da | 5734 | Defined on @code{struct} and @code{union} data. |
c2bbbb22 RP |
5735 | |
5736 | @item [] | |
5737 | Array indexing. @code{@var{a}[@var{i}]} is defined as | |
5738 | @code{*(@var{a}+@var{i})}. Same precedence as @code{->}. | |
5739 | ||
5740 | @item () | |
18fae2a8 | 5741 | Function parameter list. Same precedence as @code{->}. |
c2bbbb22 | 5742 | |
18fae2a8 | 5743 | @ifclear CONLY |
c2bbbb22 RP |
5744 | @item :: |
5745 | C++ scope resolution operator. Defined on | |
5746 | @code{struct}, @code{union}, and @code{class} types. | |
18fae2a8 | 5747 | @end ifclear |
c2bbbb22 RP |
5748 | |
5749 | @item :: | |
ed447b95 RP |
5750 | Doubled colons |
5751 | @ifclear CONLY | |
5752 | also | |
5753 | @end ifclear | |
5754 | represent the @value{GDBN} scope operator (@pxref{Expressions, | |
5755 | ,Expressions}). | |
18fae2a8 | 5756 | @ifclear CONLY |
0f153e74 | 5757 | Same precedence as @code{::}, above. |
18fae2a8 | 5758 | @end ifclear |
c2bbbb22 RP |
5759 | @end table |
5760 | ||
18fae2a8 | 5761 | @ifclear CONLY |
c2bbbb22 | 5762 | @cindex C and C++ constants |
4eb4cf57 | 5763 | @node C Constants |
93928b60 | 5764 | @subsubsection C and C++ constants |
0f153e74 | 5765 | |
18fae2a8 | 5766 | @value{GDBN} allows you to express the constants of C and C++ in the |
0f153e74 | 5767 | following ways: |
18fae2a8 RP |
5768 | @end ifclear |
5769 | @ifset CONLY | |
0f153e74 RP |
5770 | @cindex C constants |
5771 | @node C Constants | |
93928b60 | 5772 | @section C constants |
c2bbbb22 | 5773 | |
18fae2a8 | 5774 | @value{GDBN} allows you to express the constants of C in the |
c2bbbb22 | 5775 | following ways: |
18fae2a8 | 5776 | @end ifset |
c2bbbb22 RP |
5777 | |
5778 | @itemize @bullet | |
c2bbbb22 RP |
5779 | @item |
5780 | Integer constants are a sequence of digits. Octal constants are | |
af215b1a | 5781 | specified by a leading @samp{0} (i.e. zero), and hexadecimal constants by |
1041a570 | 5782 | a leading @samp{0x} or @samp{0X}. Constants may also end with a letter |
c2bbbb22 RP |
5783 | @samp{l}, specifying that the constant should be treated as a |
5784 | @code{long} value. | |
5785 | ||
5786 | @item | |
5787 | Floating point constants are a sequence of digits, followed by a decimal | |
5788 | point, followed by a sequence of digits, and optionally followed by an | |
5789 | exponent. An exponent is of the form: | |
5790 | @samp{@w{e@r{[[}+@r{]|}-@r{]}@var{nnn}}}, where @var{nnn} is another | |
5791 | sequence of digits. The @samp{+} is optional for positive exponents. | |
5792 | ||
5793 | @item | |
5794 | Enumerated constants consist of enumerated identifiers, or their | |
5795 | integral equivalents. | |
5796 | ||
5797 | @item | |
5798 | Character constants are a single character surrounded by single quotes | |
5799 | (@code{'}), or a number---the ordinal value of the corresponding character | |
5800 | (usually its @sc{ASCII} value). Within quotes, the single character may | |
5801 | be represented by a letter or by @dfn{escape sequences}, which are of | |
5802 | the form @samp{\@var{nnn}}, where @var{nnn} is the octal representation | |
5803 | of the character's ordinal value; or of the form @samp{\@var{x}}, where | |
5804 | @samp{@var{x}} is a predefined special character---for example, | |
5805 | @samp{\n} for newline. | |
5806 | ||
5807 | @item | |
5808 | String constants are a sequence of character constants surrounded | |
5809 | by double quotes (@code{"}). | |
5810 | ||
5811 | @item | |
fe715d06 RP |
5812 | Pointer constants are an integral value. You can also write pointers |
5813 | to constants using the C operator @samp{&}. | |
5814 | ||
5815 | @item | |
5816 | Array constants are comma-separated lists surrounded by braces @samp{@{} | |
5817 | and @samp{@}}; for example, @samp{@{1,2,3@}} is a three-element array of | |
5818 | integers, @samp{@{@{1,2@}, @{3,4@}, @{5,6@}@}} is a three-by-two array, | |
5819 | and @samp{@{&"hi", &"there", &"fred"@}} is a three-element array of pointers. | |
c2bbbb22 RP |
5820 | @end itemize |
5821 | ||
18fae2a8 | 5822 | @ifclear CONLY |
ed447b95 | 5823 | @node Cplus expressions |
93928b60 | 5824 | @subsubsection C++ expressions |
b80282d5 RP |
5825 | |
5826 | @cindex expressions in C++ | |
93918348 | 5827 | @value{GDBN} expression handling has a number of extensions to |
b1385986 RP |
5828 | interpret a significant subset of C++ expressions. |
5829 | ||
5830 | @cindex C++ support, not in @sc{coff} | |
5831 | @cindex @sc{coff} versus C++ | |
5832 | @cindex C++ and object formats | |
5833 | @cindex object formats and C++ | |
5834 | @cindex a.out and C++ | |
5835 | @cindex @sc{ecoff} and C++ | |
5836 | @cindex @sc{xcoff} and C++ | |
5837 | @cindex @sc{elf}/stabs and C++ | |
5838 | @cindex @sc{elf}/@sc{dwarf} and C++ | |
9a27b06e RP |
5839 | @c FIXME!! GDB may eventually be able to debug C++ using DWARF; check |
5840 | @c periodically whether this has happened... | |
b1385986 | 5841 | @quotation |
9a27b06e | 5842 | @emph{Warning:} @value{GDBN} can only debug C++ code if you compile with |
af215b1a | 5843 | the @sc{gnu} C++ compiler. Moreover, C++ debugging depends on the use of |
9a27b06e RP |
5844 | additional debugging information in the symbol table, and thus requires |
5845 | special support. @value{GDBN} has this support @emph{only} with the | |
5846 | stabs debug format. In particular, if your compiler generates a.out, | |
5847 | MIPS @sc{ecoff}, RS/6000 @sc{xcoff}, or @sc{elf} with stabs extensions | |
af215b1a | 5848 | to the symbol table, these facilities are all available. (With @sc{gnu} CC, |
9a27b06e RP |
5849 | you can use the @samp{-gstabs} option to request stabs debugging |
5850 | extensions explicitly.) Where the object code format is standard | |
5851 | @sc{coff} or @sc{dwarf} in @sc{elf}, on the other hand, most of the C++ | |
5852 | support in @value{GDBN} does @emph{not} work. | |
b1385986 | 5853 | @end quotation |
b80282d5 RP |
5854 | |
5855 | @enumerate | |
5856 | ||
5857 | @cindex member functions | |
e251e767 | 5858 | @item |
b80282d5 | 5859 | Member function calls are allowed; you can use expressions like |
1041a570 | 5860 | |
b80282d5 RP |
5861 | @example |
5862 | count = aml->GetOriginal(x, y) | |
5863 | @end example | |
5864 | ||
5865 | @kindex this | |
5866 | @cindex namespace in C++ | |
e251e767 | 5867 | @item |
b80282d5 RP |
5868 | While a member function is active (in the selected stack frame), your |
5869 | expressions have the same namespace available as the member function; | |
18fae2a8 | 5870 | that is, @value{GDBN} allows implicit references to the class instance |
b80282d5 RP |
5871 | pointer @code{this} following the same rules as C++. |
5872 | ||
5873 | @cindex call overloaded functions | |
5874 | @cindex type conversions in C++ | |
e251e767 | 5875 | @item |
9a27b06e | 5876 | You can call overloaded functions; @value{GDBN} resolves the function |
b80282d5 RP |
5877 | call to the right definition, with one restriction---you must use |
5878 | arguments of the type required by the function that you want to call. | |
9a27b06e | 5879 | @value{GDBN} does not perform conversions requiring constructors or |
b80282d5 RP |
5880 | user-defined type operators. |
5881 | ||
5882 | @cindex reference declarations | |
5883 | @item | |
af215b1a VM |
5884 | @value{GDBN} understands variables declared as C++ references; you can use |
5885 | them in expressions just as you do in C++ source---they are automatically | |
e251e767 | 5886 | dereferenced. |
b80282d5 | 5887 | |
18fae2a8 | 5888 | In the parameter list shown when @value{GDBN} displays a frame, the values of |
b80282d5 RP |
5889 | reference variables are not displayed (unlike other variables); this |
5890 | avoids clutter, since references are often used for large structures. | |
5891 | The @emph{address} of a reference variable is always shown, unless | |
1041a570 | 5892 | you have specified @samp{set print address off}. |
b80282d5 RP |
5893 | |
5894 | @item | |
18fae2a8 | 5895 | @value{GDBN} supports the C++ name resolution operator @code{::}---your |
c2bbbb22 RP |
5896 | expressions can use it just as expressions in your program do. Since |
5897 | one scope may be defined in another, you can use @code{::} repeatedly if | |
5898 | necessary, for example in an expression like | |
18fae2a8 | 5899 | @samp{@var{scope1}::@var{scope2}::@var{name}}. @value{GDBN} also allows |
c2bbbb22 | 5900 | resolving name scope by reference to source files, in both C and C++ |
93928b60 | 5901 | debugging (@pxref{Variables, ,Program variables}). |
b80282d5 RP |
5902 | @end enumerate |
5903 | ||
4eb4cf57 | 5904 | @node C Defaults |
93928b60 | 5905 | @subsubsection C and C++ defaults |
c2bbbb22 RP |
5906 | @cindex C and C++ defaults |
5907 | ||
18fae2a8 | 5908 | If you allow @value{GDBN} to set type and range checking automatically, they |
e251e767 | 5909 | both default to @code{off} whenever the working language changes to |
af215b1a VM |
5910 | C or C++. This happens regardless of whether you or @value{GDBN} |
5911 | selects the working language. | |
c2bbbb22 | 5912 | |
af215b1a VM |
5913 | If you allow @value{GDBN} to set the language automatically, it recognizes |
5914 | source files whose names end with @file{.c}, @file{.C}, or @file{.cc}, and | |
5915 | when @value{GDBN} enters code compiled from one of these files, | |
5916 | it sets the working language to C or C++. | |
18fae2a8 | 5917 | @xref{Automatically, ,Having @value{GDBN} infer the source language}, for |
c2bbbb22 RP |
5918 | further details. |
5919 | ||
09934a2b RP |
5920 | @ifset MOD2 |
5921 | @c Type checking is (a) primarily motivated by Modula-2, and (b) | |
5922 | @c unimplemented. If (b) changes, it might make sense to let this node | |
e0d3ace2 | 5923 | @c appear even if Mod-2 does not, but meanwhile ignore it. roland 16jul93. |
4eb4cf57 | 5924 | @node C Checks |
93928b60 | 5925 | @subsubsection C and C++ type and range checks |
c2bbbb22 RP |
5926 | @cindex C and C++ checks |
5927 | ||
18fae2a8 | 5928 | By default, when @value{GDBN} parses C or C++ expressions, type checking |
9a27b06e RP |
5929 | is not used. However, if you turn type checking on, @value{GDBN} |
5930 | considers two variables type equivalent if: | |
c2bbbb22 RP |
5931 | |
5932 | @itemize @bullet | |
5933 | @item | |
5934 | The two variables are structured and have the same structure, union, or | |
5935 | enumerated tag. | |
5936 | ||
e251e767 | 5937 | @item |
af215b1a | 5938 | The two variables have the same type name, or types that have been |
c2bbbb22 RP |
5939 | declared equivalent through @code{typedef}. |
5940 | ||
5941 | @ignore | |
5942 | @c leaving this out because neither J Gilmore nor R Pesch understand it. | |
5943 | @c FIXME--beers? | |
5944 | @item | |
5945 | The two @code{struct}, @code{union}, or @code{enum} variables are | |
5946 | declared in the same declaration. (Note: this may not be true for all C | |
5947 | compilers.) | |
5948 | @end ignore | |
c2bbbb22 RP |
5949 | @end itemize |
5950 | ||
5951 | Range checking, if turned on, is done on mathematical operations. Array | |
5952 | indices are not checked, since they are often used to index a pointer | |
5953 | that is not itself an array. | |
09934a2b | 5954 | @end ifset |
18fae2a8 | 5955 | @end ifclear |
c2bbbb22 | 5956 | |
18fae2a8 | 5957 | @ifclear CONLY |
4eb4cf57 | 5958 | @node Debugging C |
18fae2a8 RP |
5959 | @subsubsection @value{GDBN} and C |
5960 | @end ifclear | |
5961 | @ifset CONLY | |
5962 | @node Debugging C | |
5963 | @section @value{GDBN} and C | |
5964 | @end ifset | |
c2bbbb22 RP |
5965 | |
5966 | The @code{set print union} and @code{show print union} commands apply to | |
5967 | the @code{union} type. When set to @samp{on}, any @code{union} that is | |
1d7c3357 RP |
5968 | inside a @code{struct} |
5969 | @ifclear CONLY | |
5970 | or @code{class} | |
5971 | @end ifclear | |
9a27b06e RP |
5972 | is also printed. |
5973 | Otherwise, it appears as @samp{@{...@}}. | |
c2bbbb22 RP |
5974 | |
5975 | The @code{@@} operator aids in the debugging of dynamic arrays, formed | |
ed447b95 RP |
5976 | with pointers and a memory allocation function. @xref{Expressions, |
5977 | ,Expressions}. | |
c2bbbb22 | 5978 | |
18fae2a8 | 5979 | @ifclear CONLY |
4eb4cf57 | 5980 | @node Debugging C plus plus |
93928b60 | 5981 | @subsubsection @value{GDBN} features for C++ |
b80282d5 RP |
5982 | |
5983 | @cindex commands for C++ | |
18fae2a8 | 5984 | Some @value{GDBN} commands are particularly useful with C++, and some are |
b80282d5 RP |
5985 | designed specifically for use with C++. Here is a summary: |
5986 | ||
5987 | @table @code | |
5988 | @cindex break in overloaded functions | |
5989 | @item @r{breakpoint menus} | |
5990 | When you want a breakpoint in a function whose name is overloaded, | |
93918348 | 5991 | @value{GDBN} breakpoint menus help you specify which function definition |
93928b60 | 5992 | you want. @xref{Breakpoint Menus,,Breakpoint menus}. |
b80282d5 RP |
5993 | |
5994 | @cindex overloading in C++ | |
5995 | @item rbreak @var{regex} | |
5996 | Setting breakpoints using regular expressions is helpful for setting | |
5997 | breakpoints on overloaded functions that are not members of any special | |
e251e767 | 5998 | classes. |
93928b60 | 5999 | @xref{Set Breaks, ,Setting breakpoints}. |
b80282d5 RP |
6000 | |
6001 | @cindex C++ exception handling | |
6002 | @item catch @var{exceptions} | |
6003 | @itemx info catch | |
29a2b744 | 6004 | Debug C++ exception handling using these commands. @xref{Exception |
93928b60 | 6005 | Handling, ,Breakpoints and exceptions}. |
b80282d5 | 6006 | |
e251e767 | 6007 | @cindex inheritance |
b80282d5 RP |
6008 | @item ptype @var{typename} |
6009 | Print inheritance relationships as well as other information for type | |
e251e767 | 6010 | @var{typename}. |
1041a570 | 6011 | @xref{Symbols, ,Examining the Symbol Table}. |
b80282d5 RP |
6012 | |
6013 | @cindex C++ symbol display | |
6014 | @item set print demangle | |
6015 | @itemx show print demangle | |
6016 | @itemx set print asm-demangle | |
6017 | @itemx show print asm-demangle | |
6018 | Control whether C++ symbols display in their source form, both when | |
6019 | displaying code as C++ source and when displaying disassemblies. | |
93928b60 | 6020 | @xref{Print Settings, ,Print settings}. |
b80282d5 RP |
6021 | |
6022 | @item set print object | |
6023 | @itemx show print object | |
e251e767 | 6024 | Choose whether to print derived (actual) or declared types of objects. |
93928b60 | 6025 | @xref{Print Settings, ,Print settings}. |
b80282d5 RP |
6026 | |
6027 | @item set print vtbl | |
6028 | @itemx show print vtbl | |
6029 | Control the format for printing virtual function tables. | |
93928b60 | 6030 | @xref{Print Settings, ,Print settings}. |
6f3ec223 RP |
6031 | |
6032 | @item @r{Overloaded symbol names} | |
6033 | You can specify a particular definition of an overloaded symbol, using | |
93918348 | 6034 | the same notation that is used to declare such symbols in C++: type |
6f3ec223 | 6035 | @code{@var{symbol}(@var{types})} rather than just @var{symbol}. You can |
93918348 | 6036 | also use the @value{GDBN} command-line word completion facilities to list the |
6f3ec223 | 6037 | available choices, or to finish the type list for you. |
93928b60 | 6038 | @xref{Completion,, Command completion}, for details on how to do this. |
b80282d5 | 6039 | @end table |
09934a2b | 6040 | @ifclear MOD2 |
6370267a RP |
6041 | @c cancels "raisesections" under same conditions near bgn of chapter |
6042 | @lowersections | |
09934a2b | 6043 | @end ifclear |
b80282d5 | 6044 | |
09934a2b | 6045 | @ifset MOD2 |
4eb4cf57 | 6046 | @node Modula-2 |
c2bbbb22 RP |
6047 | @subsection Modula-2 |
6048 | @cindex Modula-2 | |
6049 | ||
ed447b95 | 6050 | The extensions made to @value{GDBN} to support Modula-2 only support |
af215b1a | 6051 | output from the @sc{gnu} Modula-2 compiler (which is currently being |
ed447b95 | 6052 | developed). Other Modula-2 compilers are not currently supported, and |
9a27b06e RP |
6053 | attempting to debug executables produced by them is most likely |
6054 | to give an error as @value{GDBN} reads in the executable's symbol | |
ed447b95 | 6055 | table. |
c2bbbb22 RP |
6056 | |
6057 | @cindex expressions in Modula-2 | |
6058 | @menu | |
6059 | * M2 Operators:: Built-in operators | |
ed447b95 RP |
6060 | * Built-In Func/Proc:: Built-in functions and procedures |
6061 | * M2 Constants:: Modula-2 constants | |
c2bbbb22 RP |
6062 | * M2 Defaults:: Default settings for Modula-2 |
6063 | * Deviations:: Deviations from standard Modula-2 | |
ed447b95 | 6064 | * M2 Checks:: Modula-2 type and range checks |
c2bbbb22 | 6065 | * M2 Scope:: The scope operators @code{::} and @code{.} |
18fae2a8 | 6066 | * GDB/M2:: @value{GDBN} and Modula-2 |
c2bbbb22 RP |
6067 | @end menu |
6068 | ||
4eb4cf57 | 6069 | @node M2 Operators |
c2bbbb22 RP |
6070 | @subsubsection Operators |
6071 | @cindex Modula-2 operators | |
6072 | ||
6073 | Operators must be defined on values of specific types. For instance, | |
6074 | @code{+} is defined on numbers, but not on structures. Operators are | |
6075 | often defined on groups of types. For the purposes of Modula-2, the | |
6076 | following definitions hold: | |
6077 | ||
6078 | @itemize @bullet | |
6079 | ||
6080 | @item | |
6081 | @emph{Integral types} consist of @code{INTEGER}, @code{CARDINAL}, and | |
6082 | their subranges. | |
6083 | ||
6084 | @item | |
6085 | @emph{Character types} consist of @code{CHAR} and its subranges. | |
6086 | ||
6087 | @item | |
6088 | @emph{Floating-point types} consist of @code{REAL}. | |
6089 | ||
6090 | @item | |
6091 | @emph{Pointer types} consist of anything declared as @code{POINTER TO | |
6092 | @var{type}}. | |
6093 | ||
6094 | @item | |
6095 | @emph{Scalar types} consist of all of the above. | |
6096 | ||
6097 | @item | |
9aa964da | 6098 | @emph{Set types} consist of @code{SET} and @code{BITSET} types. |
c2bbbb22 RP |
6099 | |
6100 | @item | |
6101 | @emph{Boolean types} consist of @code{BOOLEAN}. | |
c2bbbb22 RP |
6102 | @end itemize |
6103 | ||
6104 | @noindent | |
6105 | The following operators are supported, and appear in order of | |
6106 | increasing precedence: | |
6107 | ||
6108 | @table @code | |
c2bbbb22 RP |
6109 | @item , |
6110 | Function argument or array index separator. | |
18fae2a8 | 6111 | |
c2bbbb22 RP |
6112 | @item := |
6113 | Assignment. The value of @var{var} @code{:=} @var{value} is | |
6114 | @var{value}. | |
6115 | ||
6116 | @item <@r{, }> | |
6117 | Less than, greater than on integral, floating-point, or enumerated | |
6118 | types. | |
6119 | ||
6120 | @item <=@r{, }>= | |
6121 | Less than, greater than, less than or equal to, greater than or equal to | |
6122 | on integral, floating-point and enumerated types, or set inclusion on | |
6123 | set types. Same precedence as @code{<}. | |
6124 | ||
6125 | @item =@r{, }<>@r{, }# | |
6126 | Equality and two ways of expressing inequality, valid on scalar types. | |
18fae2a8 | 6127 | Same precedence as @code{<}. In @value{GDBN} scripts, only @code{<>} is |
c2bbbb22 RP |
6128 | available for inequality, since @code{#} conflicts with the script |
6129 | comment character. | |
6130 | ||
6131 | @item IN | |
6132 | Set membership. Defined on set types and the types of their members. | |
6133 | Same precedence as @code{<}. | |
6134 | ||
6135 | @item OR | |
6136 | Boolean disjunction. Defined on boolean types. | |
6137 | ||
6138 | @item AND@r{, }& | |
6139 | Boolean conjuction. Defined on boolean types. | |
6140 | ||
6141 | @item @@ | |
18fae2a8 | 6142 | The @value{GDBN} ``artificial array'' operator (@pxref{Expressions, ,Expressions}). |
c2bbbb22 RP |
6143 | |
6144 | @item +@r{, }- | |
6145 | Addition and subtraction on integral and floating-point types, or union | |
6146 | and difference on set types. | |
6147 | ||
6148 | @item * | |
6149 | Multiplication on integral and floating-point types, or set intersection | |
6150 | on set types. | |
6151 | ||
6152 | @item / | |
6153 | Division on floating-point types, or symmetric set difference on set | |
6154 | types. Same precedence as @code{*}. | |
6155 | ||
6156 | @item DIV@r{, }MOD | |
6157 | Integer division and remainder. Defined on integral types. Same | |
6158 | precedence as @code{*}. | |
6159 | ||
6160 | @item - | |
9aa964da | 6161 | Negative. Defined on @code{INTEGER} and @code{REAL} data. |
c2bbbb22 RP |
6162 | |
6163 | @item ^ | |
e251e767 | 6164 | Pointer dereferencing. Defined on pointer types. |
c2bbbb22 RP |
6165 | |
6166 | @item NOT | |
6167 | Boolean negation. Defined on boolean types. Same precedence as | |
6168 | @code{^}. | |
6169 | ||
6170 | @item . | |
9aa964da | 6171 | @code{RECORD} field selector. Defined on @code{RECORD} data. Same |
c2bbbb22 RP |
6172 | precedence as @code{^}. |
6173 | ||
6174 | @item [] | |
9aa964da | 6175 | Array indexing. Defined on @code{ARRAY} data. Same precedence as @code{^}. |
c2bbbb22 RP |
6176 | |
6177 | @item () | |
9aa964da | 6178 | Procedure argument list. Defined on @code{PROCEDURE} objects. Same precedence |
c2bbbb22 RP |
6179 | as @code{^}. |
6180 | ||
6181 | @item ::@r{, }. | |
18fae2a8 | 6182 | @value{GDBN} and Modula-2 scope operators. |
c2bbbb22 RP |
6183 | @end table |
6184 | ||
6185 | @quotation | |
18fae2a8 | 6186 | @emph{Warning:} Sets and their operations are not yet supported, so @value{GDBN} |
9a27b06e | 6187 | treats the use of the operator @code{IN}, or the use of operators |
c2bbbb22 RP |
6188 | @code{+}, @code{-}, @code{*}, @code{/}, @code{=}, , @code{<>}, @code{#}, |
6189 | @code{<=}, and @code{>=} on sets as an error. | |
6190 | @end quotation | |
18fae2a8 | 6191 | |
29a2b744 | 6192 | @cindex Modula-2 built-ins |
4eb4cf57 | 6193 | @node Built-In Func/Proc |
93928b60 | 6194 | @subsubsection Built-in functions and procedures |
c2bbbb22 RP |
6195 | |
6196 | Modula-2 also makes available several built-in procedures and functions. | |
6197 | In describing these, the following metavariables are used: | |
6198 | ||
6199 | @table @var | |
6200 | ||
6201 | @item a | |
6202 | represents an @code{ARRAY} variable. | |
6203 | ||
6204 | @item c | |
6205 | represents a @code{CHAR} constant or variable. | |
6206 | ||
6207 | @item i | |
6208 | represents a variable or constant of integral type. | |
6209 | ||
6210 | @item m | |
6211 | represents an identifier that belongs to a set. Generally used in the | |
6212 | same function with the metavariable @var{s}. The type of @var{s} should | |
6b51acad | 6213 | be @code{SET OF @var{mtype}} (where @var{mtype} is the type of @var{m}). |
c2bbbb22 RP |
6214 | |
6215 | @item n | |
6216 | represents a variable or constant of integral or floating-point type. | |
6217 | ||
6218 | @item r | |
6219 | represents a variable or constant of floating-point type. | |
6220 | ||
6221 | @item t | |
6222 | represents a type. | |
6223 | ||
6224 | @item v | |
6225 | represents a variable. | |
6226 | ||
6227 | @item x | |
6228 | represents a variable or constant of one of many types. See the | |
6229 | explanation of the function for details. | |
c2bbbb22 RP |
6230 | @end table |
6231 | ||
6232 | All Modula-2 built-in procedures also return a result, described below. | |
6233 | ||
6234 | @table @code | |
6235 | @item ABS(@var{n}) | |
6236 | Returns the absolute value of @var{n}. | |
6237 | ||
6238 | @item CAP(@var{c}) | |
6239 | If @var{c} is a lower case letter, it returns its upper case | |
6240 | equivalent, otherwise it returns its argument | |
6241 | ||
6242 | @item CHR(@var{i}) | |
6243 | Returns the character whose ordinal value is @var{i}. | |
6244 | ||
6245 | @item DEC(@var{v}) | |
6246 | Decrements the value in the variable @var{v}. Returns the new value. | |
6247 | ||
6248 | @item DEC(@var{v},@var{i}) | |
6249 | Decrements the value in the variable @var{v} by @var{i}. Returns the | |
6250 | new value. | |
6251 | ||
6252 | @item EXCL(@var{m},@var{s}) | |
6253 | Removes the element @var{m} from the set @var{s}. Returns the new | |
6254 | set. | |
6255 | ||
6256 | @item FLOAT(@var{i}) | |
6257 | Returns the floating point equivalent of the integer @var{i}. | |
6258 | ||
6259 | @item HIGH(@var{a}) | |
6260 | Returns the index of the last member of @var{a}. | |
6261 | ||
6262 | @item INC(@var{v}) | |
6263 | Increments the value in the variable @var{v}. Returns the new value. | |
6264 | ||
6265 | @item INC(@var{v},@var{i}) | |
6266 | Increments the value in the variable @var{v} by @var{i}. Returns the | |
6267 | new value. | |
6268 | ||
6269 | @item INCL(@var{m},@var{s}) | |
6270 | Adds the element @var{m} to the set @var{s} if it is not already | |
6271 | there. Returns the new set. | |
6272 | ||
6273 | @item MAX(@var{t}) | |
6274 | Returns the maximum value of the type @var{t}. | |
6275 | ||
6276 | @item MIN(@var{t}) | |
6277 | Returns the minimum value of the type @var{t}. | |
6278 | ||
6279 | @item ODD(@var{i}) | |
6280 | Returns boolean TRUE if @var{i} is an odd number. | |
6281 | ||
6282 | @item ORD(@var{x}) | |
6283 | Returns the ordinal value of its argument. For example, the ordinal | |
6284 | value of a character is its ASCII value (on machines supporting the | |
6285 | ASCII character set). @var{x} must be of an ordered type, which include | |
6286 | integral, character and enumerated types. | |
6287 | ||
6288 | @item SIZE(@var{x}) | |
6289 | Returns the size of its argument. @var{x} can be a variable or a type. | |
6290 | ||
6291 | @item TRUNC(@var{r}) | |
6292 | Returns the integral part of @var{r}. | |
6293 | ||
6294 | @item VAL(@var{t},@var{i}) | |
6295 | Returns the member of the type @var{t} whose ordinal value is @var{i}. | |
6296 | @end table | |
6297 | ||
6298 | @quotation | |
6299 | @emph{Warning:} Sets and their operations are not yet supported, so | |
9a27b06e | 6300 | @value{GDBN} treats the use of procedures @code{INCL} and @code{EXCL} as |
c2bbbb22 RP |
6301 | an error. |
6302 | @end quotation | |
6303 | ||
6304 | @cindex Modula-2 constants | |
4eb4cf57 | 6305 | @node M2 Constants |
c2bbbb22 RP |
6306 | @subsubsection Constants |
6307 | ||
18fae2a8 | 6308 | @value{GDBN} allows you to express the constants of Modula-2 in the following |
c2bbbb22 RP |
6309 | ways: |
6310 | ||
6311 | @itemize @bullet | |
6312 | ||
6313 | @item | |
6314 | Integer constants are simply a sequence of digits. When used in an | |
6315 | expression, a constant is interpreted to be type-compatible with the | |
6316 | rest of the expression. Hexadecimal integers are specified by a | |
6317 | trailing @samp{H}, and octal integers by a trailing @samp{B}. | |
6318 | ||
6319 | @item | |
6320 | Floating point constants appear as a sequence of digits, followed by a | |
6321 | decimal point and another sequence of digits. An optional exponent can | |
6322 | then be specified, in the form @samp{E@r{[}+@r{|}-@r{]}@var{nnn}}, where | |
6323 | @samp{@r{[}+@r{|}-@r{]}@var{nnn}} is the desired exponent. All of the | |
6324 | digits of the floating point constant must be valid decimal (base 10) | |
6325 | digits. | |
6326 | ||
6327 | @item | |
6328 | Character constants consist of a single character enclosed by a pair of | |
6329 | like quotes, either single (@code{'}) or double (@code{"}). They may | |
6330 | also be expressed by their ordinal value (their ASCII value, usually) | |
6331 | followed by a @samp{C}. | |
6332 | ||
6333 | @item | |
1041a570 RP |
6334 | String constants consist of a sequence of characters enclosed by a |
6335 | pair of like quotes, either single (@code{'}) or double (@code{"}). | |
6336 | Escape sequences in the style of C are also allowed. @xref{C | |
93928b60 | 6337 | Constants, ,C and C++ constants}, for a brief explanation of escape |
1041a570 | 6338 | sequences. |
c2bbbb22 RP |
6339 | |
6340 | @item | |
6341 | Enumerated constants consist of an enumerated identifier. | |
6342 | ||
6343 | @item | |
6344 | Boolean constants consist of the identifiers @code{TRUE} and | |
6345 | @code{FALSE}. | |
6346 | ||
6347 | @item | |
6348 | Pointer constants consist of integral values only. | |
6349 | ||
6350 | @item | |
6351 | Set constants are not yet supported. | |
c2bbbb22 RP |
6352 | @end itemize |
6353 | ||
4eb4cf57 | 6354 | @node M2 Defaults |
93928b60 | 6355 | @subsubsection Modula-2 defaults |
c2bbbb22 RP |
6356 | @cindex Modula-2 defaults |
6357 | ||
18fae2a8 | 6358 | If type and range checking are set automatically by @value{GDBN}, they |
e251e767 | 6359 | both default to @code{on} whenever the working language changes to |
18fae2a8 | 6360 | Modula-2. This happens regardless of whether you, or @value{GDBN}, |
c2bbbb22 RP |
6361 | selected the working language. |
6362 | ||
18fae2a8 | 6363 | If you allow @value{GDBN} to set the language automatically, then entering |
9a27b06e | 6364 | code compiled from a file whose name ends with @file{.mod} sets the |
18fae2a8 | 6365 | working language to Modula-2. @xref{Automatically, ,Having @value{GDBN} set |
c2bbbb22 RP |
6366 | the language automatically}, for further details. |
6367 | ||
4eb4cf57 | 6368 | @node Deviations |
93928b60 | 6369 | @subsubsection Deviations from standard Modula-2 |
c2bbbb22 RP |
6370 | @cindex Modula-2, deviations from |
6371 | ||
6372 | A few changes have been made to make Modula-2 programs easier to debug. | |
6373 | This is done primarily via loosening its type strictness: | |
6374 | ||
6375 | @itemize @bullet | |
e251e767 | 6376 | @item |
c2bbbb22 RP |
6377 | Unlike in standard Modula-2, pointer constants can be formed by |
6378 | integers. This allows you to modify pointer variables during | |
6379 | debugging. (In standard Modula-2, the actual address contained in a | |
6380 | pointer variable is hidden from you; it can only be modified | |
6381 | through direct assignment to another pointer variable or expression that | |
6382 | returned a pointer.) | |
6383 | ||
e251e767 | 6384 | @item |
c2bbbb22 | 6385 | C escape sequences can be used in strings and characters to represent |
9a27b06e | 6386 | non-printable characters. @value{GDBN} prints out strings with these |
c2bbbb22 RP |
6387 | escape sequences embedded. Single non-printable characters are |
6388 | printed using the @samp{CHR(@var{nnn})} format. | |
6389 | ||
6390 | @item | |
6391 | The assignment operator (@code{:=}) returns the value of its right-hand | |
6392 | argument. | |
6393 | ||
6394 | @item | |
29a2b744 | 6395 | All built-in procedures both modify @emph{and} return their argument. |
e251e767 | 6396 | @end itemize |
c2bbbb22 | 6397 | |
4eb4cf57 | 6398 | @node M2 Checks |
93928b60 | 6399 | @subsubsection Modula-2 type and range checks |
c2bbbb22 RP |
6400 | @cindex Modula-2 checks |
6401 | ||
6402 | @quotation | |
18fae2a8 | 6403 | @emph{Warning:} in this release, @value{GDBN} does not yet perform type or |
c2bbbb22 RP |
6404 | range checking. |
6405 | @end quotation | |
6406 | @c FIXME remove warning when type/range checks added | |
6407 | ||
18fae2a8 | 6408 | @value{GDBN} considers two Modula-2 variables type equivalent if: |
c2bbbb22 RP |
6409 | |
6410 | @itemize @bullet | |
6411 | @item | |
6412 | They are of types that have been declared equivalent via a @code{TYPE | |
6413 | @var{t1} = @var{t2}} statement | |
6414 | ||
6415 | @item | |
6416 | They have been declared on the same line. (Note: This is true of the | |
af215b1a | 6417 | @sc{gnu} Modula-2 compiler, but it may not be true of other compilers.) |
c2bbbb22 RP |
6418 | @end itemize |
6419 | ||
6420 | As long as type checking is enabled, any attempt to combine variables | |
6421 | whose types are not equivalent is an error. | |
6422 | ||
6423 | Range checking is done on all mathematical operations, assignment, array | |
29a2b744 | 6424 | index bounds, and all built-in functions and procedures. |
c2bbbb22 | 6425 | |
4eb4cf57 | 6426 | @node M2 Scope |
c2bbbb22 RP |
6427 | @subsubsection The scope operators @code{::} and @code{.} |
6428 | @cindex scope | |
6429 | @kindex . | |
e94b4a2b | 6430 | @cindex colon, doubled as scope operator |
1041a570 RP |
6431 | @ifinfo |
6432 | @kindex colon-colon | |
ed447b95 | 6433 | @c Info cannot handle :: but TeX can. |
1041a570 RP |
6434 | @end ifinfo |
6435 | @iftex | |
c2bbbb22 | 6436 | @kindex :: |
1041a570 | 6437 | @end iftex |
c2bbbb22 RP |
6438 | |
6439 | There are a few subtle differences between the Modula-2 scope operator | |
18fae2a8 | 6440 | (@code{.}) and the @value{GDBN} scope operator (@code{::}). The two have |
c2bbbb22 RP |
6441 | similar syntax: |
6442 | ||
6443 | @example | |
6444 | ||
6445 | @var{module} . @var{id} | |
6446 | @var{scope} :: @var{id} | |
c2bbbb22 RP |
6447 | @end example |
6448 | ||
6449 | @noindent | |
6450 | where @var{scope} is the name of a module or a procedure, | |
29a2b744 RP |
6451 | @var{module} the name of a module, and @var{id} is any declared |
6452 | identifier within your program, except another module. | |
c2bbbb22 | 6453 | |
18fae2a8 | 6454 | Using the @code{::} operator makes @value{GDBN} search the scope |
c2bbbb22 | 6455 | specified by @var{scope} for the identifier @var{id}. If it is not |
9a27b06e | 6456 | found in the specified scope, then @value{GDBN} searches all scopes |
c2bbbb22 RP |
6457 | enclosing the one specified by @var{scope}. |
6458 | ||
18fae2a8 | 6459 | Using the @code{.} operator makes @value{GDBN} search the current scope for |
c2bbbb22 RP |
6460 | the identifier specified by @var{id} that was imported from the |
6461 | definition module specified by @var{module}. With this operator, it is | |
6462 | an error if the identifier @var{id} was not imported from definition | |
6463 | module @var{module}, or if @var{id} is not an identifier in | |
6464 | @var{module}. | |
6465 | ||
4eb4cf57 | 6466 | @node GDB/M2 |
18fae2a8 | 6467 | @subsubsection @value{GDBN} and Modula-2 |
c2bbbb22 | 6468 | |
18fae2a8 | 6469 | Some @value{GDBN} commands have little use when debugging Modula-2 programs. |
c2bbbb22 RP |
6470 | Five subcommands of @code{set print} and @code{show print} apply |
6471 | specifically to C and C++: @samp{vtbl}, @samp{demangle}, | |
6472 | @samp{asm-demangle}, @samp{object}, and @samp{union}. The first four | |
93918348 | 6473 | apply to C++, and the last to the C @code{union} type, which has no direct |
c2bbbb22 RP |
6474 | analogue in Modula-2. |
6475 | ||
1041a570 | 6476 | The @code{@@} operator (@pxref{Expressions, ,Expressions}), while available |
c2bbbb22 RP |
6477 | while using any language, is not useful with Modula-2. Its |
6478 | intent is to aid the debugging of @dfn{dynamic arrays}, which cannot be | |
6479 | created in Modula-2 as they can in C or C++. However, because an | |
6480 | address can be specified by an integral constant, the construct | |
1041a570 | 6481 | @samp{@{@var{type}@}@var{adrexp}} is still useful. (@pxref{Expressions, ,Expressions}) |
18fae2a8 | 6482 | |
c2bbbb22 | 6483 | @cindex @code{#} in Modula-2 |
18fae2a8 | 6484 | In @value{GDBN} scripts, the Modula-2 inequality operator @code{#} is |
c2bbbb22 | 6485 | interpreted as the beginning of a comment. Use @code{<>} instead. |
09934a2b | 6486 | @end ifset |
da374d80 | 6487 | @end ifclear |
4eb4cf57 RP |
6488 | |
6489 | @node Symbols | |
70b88761 RP |
6490 | @chapter Examining the Symbol Table |
6491 | ||
6492 | The commands described in this section allow you to inquire about the | |
6493 | symbols (names of variables, functions and types) defined in your | |
6494 | program. This information is inherent in the text of your program and | |
18fae2a8 RP |
6495 | does not change as your program executes. @value{GDBN} finds it in your |
6496 | program's symbol table, in the file indicated when you started @value{GDBN} | |
93928b60 RP |
6497 | (@pxref{File Options, ,Choosing files}), or by one of the |
6498 | file-management commands (@pxref{Files, ,Commands to specify files}). | |
70b88761 | 6499 | |
6c380b13 RP |
6500 | @cindex symbol names |
6501 | @cindex names of symbols | |
6502 | @cindex quoting names | |
6503 | Occasionally, you may need to refer to symbols that contain unusual | |
18fae2a8 | 6504 | characters, which @value{GDBN} ordinarily treats as word delimiters. The |
6c380b13 | 6505 | most frequent case is in referring to static variables in other |
93928b60 | 6506 | source files (@pxref{Variables,,Program variables}). File names |
18fae2a8 | 6507 | are recorded in object files as debugging symbols, but @value{GDBN} would |
6c380b13 | 6508 | ordinarily parse a typical file name, like @file{foo.c}, as the three words |
18fae2a8 | 6509 | @samp{foo} @samp{.} @samp{c}. To allow @value{GDBN} to recognize |
6c380b13 RP |
6510 | @samp{foo.c} as a single symbol, enclose it in single quotes; for example, |
6511 | ||
6512 | @example | |
6513 | p 'foo.c'::x | |
6514 | @end example | |
6515 | ||
6516 | @noindent | |
6517 | looks up the value of @code{x} in the scope of the file @file{foo.c}. | |
6518 | ||
70b88761 | 6519 | @table @code |
70b88761 | 6520 | @kindex info address |
af215b1a | 6521 | @item info address @var{symbol} |
70b88761 RP |
6522 | Describe where the data for @var{symbol} is stored. For a register |
6523 | variable, this says which register it is kept in. For a non-register | |
6524 | local variable, this prints the stack-frame offset at which the variable | |
6525 | is always stored. | |
6526 | ||
6527 | Note the contrast with @samp{print &@var{symbol}}, which does not work | |
6b51acad | 6528 | at all for a register variable, and for a stack local variable prints |
70b88761 RP |
6529 | the exact address of the current instantiation of the variable. |
6530 | ||
70b88761 | 6531 | @kindex whatis |
af215b1a | 6532 | @item whatis @var{exp} |
70b88761 RP |
6533 | Print the data type of expression @var{exp}. @var{exp} is not |
6534 | actually evaluated, and any side-effecting operations (such as | |
6535 | assignments or function calls) inside it do not take place. | |
1041a570 | 6536 | @xref{Expressions, ,Expressions}. |
70b88761 RP |
6537 | |
6538 | @item whatis | |
6539 | Print the data type of @code{$}, the last value in the value history. | |
6540 | ||
70b88761 | 6541 | @kindex ptype |
af215b1a | 6542 | @item ptype @var{typename} |
70b88761 RP |
6543 | Print a description of data type @var{typename}. @var{typename} may be |
6544 | the name of a type, or for C code it may have the form | |
25f9d853 JK |
6545 | @ifclear CONLY |
6546 | @samp{class @var{class-name}}, | |
6547 | @end ifclear | |
70b88761 | 6548 | @samp{struct @var{struct-tag}}, @samp{union @var{union-tag}} or |
1041a570 | 6549 | @samp{enum @var{enum-tag}}. |
70b88761 RP |
6550 | |
6551 | @item ptype @var{exp} | |
e0dacfd1 | 6552 | @itemx ptype |
70b88761 | 6553 | Print a description of the type of expression @var{exp}. @code{ptype} |
1041a570 | 6554 | differs from @code{whatis} by printing a detailed description, instead |
ed447b95 RP |
6555 | of just the name of the type. |
6556 | ||
6557 | For example, for this variable declaration: | |
1041a570 | 6558 | |
70b88761 RP |
6559 | @example |
6560 | struct complex @{double real; double imag;@} v; | |
6561 | @end example | |
1041a570 | 6562 | |
70b88761 | 6563 | @noindent |
ed447b95 | 6564 | the two commands give this output: |
1041a570 | 6565 | |
70b88761 | 6566 | @example |
1041a570 | 6567 | @group |
18fae2a8 | 6568 | (@value{GDBP}) whatis v |
70b88761 | 6569 | type = struct complex |
18fae2a8 | 6570 | (@value{GDBP}) ptype v |
70b88761 RP |
6571 | type = struct complex @{ |
6572 | double real; | |
6573 | double imag; | |
6574 | @} | |
1041a570 | 6575 | @end group |
70b88761 | 6576 | @end example |
1041a570 | 6577 | |
e0dacfd1 RP |
6578 | @noindent |
6579 | As with @code{whatis}, using @code{ptype} without an argument refers to | |
6580 | the type of @code{$}, the last value in the value history. | |
70b88761 | 6581 | |
af215b1a | 6582 | @kindex info types |
70b88761 RP |
6583 | @item info types @var{regexp} |
6584 | @itemx info types | |
70b88761 RP |
6585 | Print a brief description of all types whose name matches @var{regexp} |
6586 | (or all types in your program, if you supply no argument). Each | |
6587 | complete typename is matched as though it were a complete line; thus, | |
6588 | @samp{i type value} gives information on all types in your program whose | |
6589 | name includes the string @code{value}, but @samp{i type ^value$} gives | |
6590 | information only on types whose complete name is @code{value}. | |
6591 | ||
6592 | This command differs from @code{ptype} in two ways: first, like | |
6593 | @code{whatis}, it does not print a detailed description; second, it | |
6594 | lists all source files where a type is defined. | |
6595 | ||
70b88761 | 6596 | @kindex info source |
af215b1a | 6597 | @item info source |
70b88761 | 6598 | Show the name of the current source file---that is, the source file for |
c2bbbb22 RP |
6599 | the function containing the current point of execution---and the language |
6600 | it was written in. | |
70b88761 | 6601 | |
70b88761 | 6602 | @kindex info sources |
af215b1a | 6603 | @item info sources |
29a2b744 | 6604 | Print the names of all source files in your program for which there is |
b80282d5 RP |
6605 | debugging information, organized into two lists: files whose symbols |
6606 | have already been read, and files whose symbols will be read when needed. | |
70b88761 | 6607 | |
70b88761 | 6608 | @kindex info functions |
af215b1a | 6609 | @item info functions |
70b88761 RP |
6610 | Print the names and data types of all defined functions. |
6611 | ||
6612 | @item info functions @var{regexp} | |
6613 | Print the names and data types of all defined functions | |
6614 | whose names contain a match for regular expression @var{regexp}. | |
6615 | Thus, @samp{info fun step} finds all functions whose names | |
6616 | include @code{step}; @samp{info fun ^step} finds those whose names | |
6617 | start with @code{step}. | |
6618 | ||
70b88761 | 6619 | @kindex info variables |
af215b1a | 6620 | @item info variables |
70b88761 RP |
6621 | Print the names and data types of all variables that are declared |
6622 | outside of functions (i.e., excluding local variables). | |
6623 | ||
6624 | @item info variables @var{regexp} | |
6625 | Print the names and data types of all variables (except for local | |
6626 | variables) whose names contain a match for regular expression | |
6627 | @var{regexp}. | |
6628 | ||
70b88761 RP |
6629 | @ignore |
6630 | This was never implemented. | |
af215b1a | 6631 | @kindex info methods |
70b88761 RP |
6632 | @item info methods |
6633 | @itemx info methods @var{regexp} | |
70b88761 RP |
6634 | The @code{info methods} command permits the user to examine all defined |
6635 | methods within C++ program, or (with the @var{regexp} argument) a | |
6636 | specific set of methods found in the various C++ classes. Many | |
6637 | C++ classes provide a large number of methods. Thus, the output | |
6638 | from the @code{ptype} command can be overwhelming and hard to use. The | |
6639 | @code{info-methods} command filters the methods, printing only those | |
6640 | which match the regular-expression @var{regexp}. | |
6641 | @end ignore | |
6642 | ||
af215b1a VM |
6643 | @cindex reloading symbols |
6644 | Some systems allow individual object files that make up your program to | |
6645 | be replaced without stopping and restarting your program. | |
6646 | @ifset VXWORKS | |
6647 | For example, in VxWorks you can simply recompile a defective object file | |
6648 | and keep on running. | |
6649 | @end ifset | |
6650 | If you are running on one of these systems, you can allow @value{GDBN} to | |
6651 | reload the symbols for automatically relinked modules: | |
6652 | ||
6653 | @table @code | |
6654 | @kindex set symbol-reloading | |
6655 | @item set symbol-reloading on | |
6656 | Replace symbol definitions for the corresponding source file when an | |
6657 | object file with a particular name is seen again. | |
6658 | ||
6659 | @item set symbol-reloading off | |
6660 | Do not replace symbol definitions when re-encountering object files of | |
6661 | the same name. This is the default state; if you are not running on a | |
6662 | system that permits automatically relinking modules, you should leave | |
6663 | @code{symbol-reloading} off, since otherwise @value{GDBN} may discard symbols | |
6664 | when linking large programs, that may contain several modules (from | |
6665 | different directories or libraries) with the same name. | |
6666 | ||
6667 | @kindex show symbol-reloading | |
6668 | @item show symbol-reloading | |
6669 | Show the current @code{on} or @code{off} setting. | |
6670 | @end table | |
6671 | ||
d48da190 | 6672 | @kindex maint print symbols |
440d9834 | 6673 | @cindex symbol dump |
d48da190 | 6674 | @kindex maint print psymbols |
440d9834 | 6675 | @cindex partial symbol dump |
af215b1a VM |
6676 | @item maint print symbols @var{filename} |
6677 | @itemx maint print psymbols @var{filename} | |
6678 | @itemx maint print msymbols @var{filename} | |
440d9834 | 6679 | Write a dump of debugging symbol data into the file @var{filename}. |
18fae2a8 | 6680 | These commands are used to debug the @value{GDBN} symbol-reading code. Only |
d48da190 | 6681 | symbols with debugging data are included. If you use @samp{maint print |
18fae2a8 | 6682 | symbols}, @value{GDBN} includes all the symbols for which it has already |
d48da190 | 6683 | collected full details: that is, @var{filename} reflects symbols for |
18fae2a8 | 6684 | only those files whose symbols @value{GDBN} has read. You can use the |
d48da190 RP |
6685 | command @code{info sources} to find out which files these are. If you |
6686 | use @samp{maint print psymbols} instead, the dump shows information about | |
18fae2a8 RP |
6687 | symbols that @value{GDBN} only knows partially---that is, symbols defined in |
6688 | files that @value{GDBN} has skimmed, but not yet read completely. Finally, | |
d48da190 | 6689 | @samp{maint print msymbols} dumps just the minimal symbol information |
18fae2a8 | 6690 | required for each object file from which @value{GDBN} has read some symbols. |
d55320a0 RP |
6691 | @xref{Files, ,Commands to specify files}, for a discussion of how |
6692 | @value{GDBN} reads symbols (in the description of @code{symbol-file}). | |
70b88761 RP |
6693 | @end table |
6694 | ||
4eb4cf57 | 6695 | @node Altering |
70b88761 RP |
6696 | @chapter Altering Execution |
6697 | ||
29a2b744 | 6698 | Once you think you have found an error in your program, you might want to |
70b88761 RP |
6699 | find out for certain whether correcting the apparent error would lead to |
6700 | correct results in the rest of the run. You can find the answer by | |
18fae2a8 | 6701 | experiment, using the @value{GDBN} features for altering execution of the |
70b88761 RP |
6702 | program. |
6703 | ||
6704 | For example, you can store new values into variables or memory | |
1d7c3357 | 6705 | locations, |
18fae2a8 | 6706 | @ifclear BARETARGET |
1d7c3357 | 6707 | give your program a signal, restart it |
18fae2a8 | 6708 | @end ifclear |
1d7c3357 RP |
6709 | @ifset BARETARGET |
6710 | restart your program | |
6711 | @end ifset | |
af215b1a | 6712 | at a different address, or even return prematurely from a function. |
18fae2a8 | 6713 | |
18fae2a8 | 6714 | @menu |
ed447b95 RP |
6715 | * Assignment:: Assignment to variables |
6716 | * Jumping:: Continuing at a different address | |
1d7c3357 | 6717 | @ifclear BARETARGET |
ed447b95 | 6718 | * Signaling:: Giving your program a signal |
18fae2a8 | 6719 | @end ifclear |
b0157555 | 6720 | |
ed447b95 RP |
6721 | * Returning:: Returning from a function |
6722 | * Calling:: Calling your program's functions | |
6723 | * Patching:: Patching your program | |
18fae2a8 | 6724 | @end menu |
70b88761 | 6725 | |
4eb4cf57 | 6726 | @node Assignment |
93928b60 | 6727 | @section Assignment to variables |
70b88761 RP |
6728 | |
6729 | @cindex assignment | |
6730 | @cindex setting variables | |
6731 | To alter the value of a variable, evaluate an assignment expression. | |
1041a570 | 6732 | @xref{Expressions, ,Expressions}. For example, |
70b88761 RP |
6733 | |
6734 | @example | |
6735 | print x=4 | |
6736 | @end example | |
6737 | ||
6738 | @noindent | |
1041a570 | 6739 | stores the value 4 into the variable @code{x}, and then prints the |
4eb4cf57 | 6740 | value of the assignment expression (which is 4). |
18fae2a8 RP |
6741 | @ifclear CONLY |
6742 | @xref{Languages, ,Using @value{GDBN} with Different Languages}, for more | |
4eb4cf57 | 6743 | information on operators in supported languages. |
18fae2a8 | 6744 | @end ifclear |
70b88761 | 6745 | |
70b88761 RP |
6746 | @kindex set variable |
6747 | @cindex variables, setting | |
6748 | If you are not interested in seeing the value of the assignment, use the | |
6749 | @code{set} command instead of the @code{print} command. @code{set} is | |
93928b60 RP |
6750 | really the same as @code{print} except that the expression's value is |
6751 | not printed and is not put in the value history (@pxref{Value History, | |
6752 | ,Value history}). The expression is evaluated only for its effects. | |
70b88761 RP |
6753 | |
6754 | If the beginning of the argument string of the @code{set} command | |
6755 | appears identical to a @code{set} subcommand, use the @code{set | |
6756 | variable} command instead of just @code{set}. This command is identical | |
ed447b95 RP |
6757 | to @code{set} except for its lack of subcommands. For example, if |
6758 | your program has a variable @code{width}, you get | |
6759 | an error if you try to set a new value with just @samp{set width=13}, | |
6760 | because @value{GDBN} has the command @code{set width}: | |
1041a570 | 6761 | |
70b88761 | 6762 | @example |
18fae2a8 | 6763 | (@value{GDBP}) whatis width |
70b88761 | 6764 | type = double |
18fae2a8 | 6765 | (@value{GDBP}) p width |
70b88761 | 6766 | $4 = 13 |
18fae2a8 | 6767 | (@value{GDBP}) set width=47 |
70b88761 RP |
6768 | Invalid syntax in expression. |
6769 | @end example | |
1041a570 | 6770 | |
70b88761 | 6771 | @noindent |
ed447b95 RP |
6772 | The invalid expression, of course, is @samp{=47}. In |
6773 | order to actually set the program's variable @code{width}, use | |
1041a570 | 6774 | |
70b88761 | 6775 | @example |
18fae2a8 | 6776 | (@value{GDBP}) set var width=47 |
70b88761 RP |
6777 | @end example |
6778 | ||
18fae2a8 | 6779 | @value{GDBN} allows more implicit conversions in assignments than C; you can |
1041a570 | 6780 | freely store an integer value into a pointer variable or vice versa, |
ed447b95 | 6781 | and you can convert any structure to any other structure that is the |
1041a570 | 6782 | same length or shorter. |
e251e767 | 6783 | @comment FIXME: how do structs align/pad in these conversions? |
e0d3ace2 | 6784 | @comment /doc@cygnus.com 18dec1990 |
70b88761 RP |
6785 | |
6786 | To store values into arbitrary places in memory, use the @samp{@{@dots{}@}} | |
6787 | construct to generate a value of specified type at a specified address | |
1041a570 | 6788 | (@pxref{Expressions, ,Expressions}). For example, @code{@{int@}0x83040} refers |
70b88761 RP |
6789 | to memory location @code{0x83040} as an integer (which implies a certain size |
6790 | and representation in memory), and | |
6791 | ||
6792 | @example | |
6793 | set @{int@}0x83040 = 4 | |
6794 | @end example | |
6795 | ||
6796 | @noindent | |
6797 | stores the value 4 into that memory location. | |
6798 | ||
4eb4cf57 | 6799 | @node Jumping |
93928b60 | 6800 | @section Continuing at a different address |
70b88761 | 6801 | |
29a2b744 | 6802 | Ordinarily, when you continue your program, you do so at the place where |
70b88761 RP |
6803 | it stopped, with the @code{continue} command. You can instead continue at |
6804 | an address of your own choosing, with the following commands: | |
6805 | ||
6806 | @table @code | |
70b88761 | 6807 | @kindex jump |
af215b1a | 6808 | @item jump @var{linespec} |
9a27b06e | 6809 | Resume execution at line @var{linespec}. Execution stops again |
29a2b744 | 6810 | immediately if there is a breakpoint there. @xref{List, ,Printing |
93928b60 | 6811 | source lines}, for a description of the different forms of |
29a2b744 | 6812 | @var{linespec}. |
70b88761 RP |
6813 | |
6814 | The @code{jump} command does not change the current stack frame, or | |
6815 | the stack pointer, or the contents of any memory location or any | |
6816 | register other than the program counter. If line @var{linespec} is in | |
6817 | a different function from the one currently executing, the results may | |
6818 | be bizarre if the two functions expect different patterns of arguments or | |
6819 | of local variables. For this reason, the @code{jump} command requests | |
6820 | confirmation if the specified line is not in the function currently | |
6821 | executing. However, even bizarre results are predictable if you are | |
29a2b744 | 6822 | well acquainted with the machine-language code of your program. |
70b88761 RP |
6823 | |
6824 | @item jump *@var{address} | |
6825 | Resume execution at the instruction at address @var{address}. | |
6826 | @end table | |
6827 | ||
6828 | You can get much the same effect as the @code{jump} command by storing a | |
6829 | new value into the register @code{$pc}. The difference is that this | |
af215b1a | 6830 | does not start your program running; it only changes the address of where it |
9a27b06e | 6831 | @emph{will} run when you continue. For example, |
70b88761 RP |
6832 | |
6833 | @example | |
6834 | set $pc = 0x485 | |
6835 | @end example | |
6836 | ||
6837 | @noindent | |
9a27b06e | 6838 | makes the next @code{continue} command or stepping command execute at |
1041a570 | 6839 | address @code{0x485}, rather than at the address where your program stopped. |
93928b60 | 6840 | @xref{Continuing and Stepping, ,Continuing and stepping}. |
70b88761 | 6841 | |
af215b1a VM |
6842 | The most common occasion to use the @code{jump} command is to back up-- |
6843 | perhaps with more breakpoints set--over a portion of a program that has | |
70b88761 RP |
6844 | already executed, in order to examine its execution in more detail. |
6845 | ||
18fae2a8 | 6846 | @ifclear BARETARGET |
70b88761 | 6847 | @c @group |
ed447b95 RP |
6848 | @node Signaling |
6849 | @section Giving your program a signal | |
70b88761 RP |
6850 | |
6851 | @table @code | |
70b88761 | 6852 | @kindex signal |
af215b1a | 6853 | @item signal @var{signal} |
6b51acad | 6854 | Resume execution where your program stopped, but immediately give it the |
fd32a1dd JK |
6855 | signal @var{signal}. @var{signal} can be the name or the number of a |
6856 | signal. For example, on many systems @code{signal 2} and @code{signal | |
6857 | SIGINT} are both ways of sending an interrupt signal. | |
70b88761 | 6858 | |
fd32a1dd | 6859 | Alternatively, if @var{signal} is zero, continue execution without |
29a2b744 | 6860 | giving a signal. This is useful when your program stopped on account of |
70b88761 RP |
6861 | a signal and would ordinary see the signal when resumed with the |
6862 | @code{continue} command; @samp{signal 0} causes it to resume without a | |
6863 | signal. | |
6864 | ||
6865 | @code{signal} does not repeat when you press @key{RET} a second time | |
6866 | after executing the command. | |
6867 | @end table | |
6868 | @c @end group | |
fd32a1dd JK |
6869 | |
6870 | Invoking the @code{signal} command is not the same as invoking the | |
6871 | @code{kill} utility from the shell. Sending a signal with @code{kill} | |
6872 | causes @value{GDBN} to decide what to do with the signal depending on | |
6873 | the signal handling tables (@pxref{Signals}). The @code{signal} command | |
6874 | passes the signal directly to your program. | |
6875 | ||
18fae2a8 | 6876 | @end ifclear |
70b88761 | 6877 | |
4eb4cf57 | 6878 | @node Returning |
93928b60 | 6879 | @section Returning from a function |
70b88761 RP |
6880 | |
6881 | @table @code | |
70b88761 RP |
6882 | @cindex returning from a function |
6883 | @kindex return | |
af215b1a VM |
6884 | @item return |
6885 | @itemx return @var{expression} | |
70b88761 RP |
6886 | You can cancel execution of a function call with the @code{return} |
6887 | command. If you give an | |
6888 | @var{expression} argument, its value is used as the function's return | |
e251e767 | 6889 | value. |
70b88761 RP |
6890 | @end table |
6891 | ||
18fae2a8 | 6892 | When you use @code{return}, @value{GDBN} discards the selected stack frame |
70b88761 RP |
6893 | (and all frames within it). You can think of this as making the |
6894 | discarded frame return prematurely. If you wish to specify a value to | |
6895 | be returned, give that value as the argument to @code{return}. | |
6896 | ||
29a2b744 | 6897 | This pops the selected stack frame (@pxref{Selection, ,Selecting a |
93928b60 | 6898 | frame}), and any other frames inside of it, leaving its caller as the |
29a2b744 RP |
6899 | innermost remaining frame. That frame becomes selected. The |
6900 | specified value is stored in the registers used for returning values | |
6901 | of functions. | |
70b88761 RP |
6902 | |
6903 | The @code{return} command does not resume execution; it leaves the | |
6904 | program stopped in the state that would exist if the function had just | |
1041a570 | 6905 | returned. In contrast, the @code{finish} command (@pxref{Continuing |
93928b60 | 6906 | and Stepping, ,Continuing and stepping}) resumes execution until the |
1041a570 | 6907 | selected stack frame returns naturally. |
70b88761 | 6908 | |
4eb4cf57 | 6909 | @node Calling |
ed447b95 | 6910 | @section Calling program functions |
70b88761 RP |
6911 | |
6912 | @cindex calling functions | |
6913 | @kindex call | |
6914 | @table @code | |
6915 | @item call @var{expr} | |
6916 | Evaluate the expression @var{expr} without displaying @code{void} | |
6917 | returned values. | |
6918 | @end table | |
6919 | ||
6920 | You can use this variant of the @code{print} command if you want to | |
6921 | execute a function from your program, but without cluttering the output | |
af215b1a VM |
6922 | with @code{void} returned values. If the result is not void, it |
6923 | is printed and saved in the value history. | |
6924 | ||
6925 | A new user-controlled variable, @var{call_scratch_address}, specifies | |
6926 | the location of a scratch area to be used when @value{GDBN} calls a | |
6927 | function in the target. This is necessary because the usual method | |
6928 | of putting the scratch area on the stack does not work in systems that | |
6929 | have separate instruction and data spaces. | |
70b88761 | 6930 | |
4eb4cf57 | 6931 | @node Patching |
ed447b95 | 6932 | @section Patching programs |
c338a2fd RP |
6933 | @cindex patching binaries |
6934 | @cindex writing into executables | |
1d7c3357 | 6935 | @ifclear BARETARGET |
c338a2fd | 6936 | @cindex writing into corefiles |
1d7c3357 | 6937 | @end ifclear |
1041a570 | 6938 | |
18fae2a8 | 6939 | By default, @value{GDBN} opens the file containing your program's executable |
1d7c3357 RP |
6940 | code |
6941 | @ifclear BARETARGET | |
6942 | (or the corefile) | |
6943 | @end ifclear | |
6944 | read-only. This prevents accidental alterations | |
c338a2fd RP |
6945 | to machine code; but it also prevents you from intentionally patching |
6946 | your program's binary. | |
6947 | ||
6948 | If you'd like to be able to patch the binary, you can specify that | |
6949 | explicitly with the @code{set write} command. For example, you might | |
6950 | want to turn on internal debugging flags, or even to make emergency | |
e251e767 | 6951 | repairs. |
c338a2fd RP |
6952 | |
6953 | @table @code | |
af215b1a | 6954 | @kindex set write |
c338a2fd RP |
6955 | @item set write on |
6956 | @itemx set write off | |
9a27b06e | 6957 | If you specify @samp{set write on}, @value{GDBN} opens executable |
18fae2a8 | 6958 | @ifclear BARETARGET |
0f153e74 | 6959 | and core |
18fae2a8 | 6960 | @end ifclear |
0f153e74 | 6961 | files for both reading and writing; if you specify @samp{set write |
9a27b06e | 6962 | off} (the default), @value{GDBN} opens them read-only. |
c338a2fd | 6963 | |
1d7c3357 RP |
6964 | If you have already loaded a file, you must load it again (using the |
6965 | @code{exec-file} | |
6966 | @ifclear BARETARGET | |
6967 | or @code{core-file} | |
6968 | @end ifclear | |
6969 | command) after changing @code{set write}, for your new setting to take | |
6970 | effect. | |
c338a2fd RP |
6971 | |
6972 | @item show write | |
7d7ff5f6 | 6973 | @kindex show write |
0f153e74 | 6974 | Display whether executable files |
18fae2a8 | 6975 | @ifclear BARETARGET |
0f153e74 | 6976 | and core files |
18fae2a8 | 6977 | @end ifclear |
9a27b06e | 6978 | are opened for writing as well as reading. |
c338a2fd RP |
6979 | @end table |
6980 | ||
18fae2a8 | 6981 | @node GDB Files |
93918348 | 6982 | @chapter @value{GDBN} Files |
70b88761 | 6983 | |
18fae2a8 | 6984 | @value{GDBN} needs to know the file name of the program to be debugged, both in |
4eb4cf57 | 6985 | order to read its symbol table and in order to start your program. |
18fae2a8 | 6986 | @ifclear BARETARGET |
93918348 RP |
6987 | To debug a core dump of a previous run, you must also tell @value{GDBN} |
6988 | the name of the core dump file. | |
18fae2a8 | 6989 | @end ifclear |
1041a570 | 6990 | |
70b88761 | 6991 | @menu |
ed447b95 RP |
6992 | * Files:: Commands to specify files |
6993 | * Symbol Errors:: Errors reading symbol files | |
70b88761 RP |
6994 | @end menu |
6995 | ||
4eb4cf57 | 6996 | @node Files |
93928b60 | 6997 | @section Commands to specify files |
70b88761 | 6998 | @cindex symbol table |
70b88761 | 6999 | |
18fae2a8 | 7000 | @ifclear BARETARGET |
0f153e74 | 7001 | @cindex core dump file |
af215b1a VM |
7002 | You may want to specify executable and core dump file names. |
7003 | The usual way to do this is at start-up time, using the arguments to | |
7004 | @value{GDBN}'s start-up commands (@pxref{Invocation, , | |
7005 | Getting In and Out of @value{GDBN}}). | |
18fae2a8 RP |
7006 | @end ifclear |
7007 | @ifset BARETARGET | |
4eb4cf57 | 7008 | The usual way to specify an executable file name is with |
18fae2a8 RP |
7009 | the command argument given when you start @value{GDBN}, (@pxref{Invocation, |
7010 | ,Getting In and Out of @value{GDBN}}. | |
7011 | @end ifset | |
70b88761 RP |
7012 | |
7013 | Occasionally it is necessary to change to a different file during a | |
93918348 RP |
7014 | @value{GDBN} session. Or you may run @value{GDBN} and forget to specify |
7015 | a file you want to use. In these situations the @value{GDBN} commands | |
7016 | to specify new files are useful. | |
70b88761 RP |
7017 | |
7018 | @table @code | |
70b88761 RP |
7019 | @cindex executable file |
7020 | @kindex file | |
af215b1a | 7021 | @item file @var{filename} |
70b88761 RP |
7022 | Use @var{filename} as the program to be debugged. It is read for its |
7023 | symbols and for the contents of pure memory. It is also the program | |
7024 | executed when you use the @code{run} command. If you do not specify a | |
af215b1a VM |
7025 | directory and the file is not found in the @value{GDBN} working directory, |
7026 | @value{GDBN} uses the environment variable @code{PATH} as a list of | |
7027 | directories to search, just as the shell does when looking for a program | |
7028 | to run. You can change the value of this variable, for both @value{GDBN} | |
7029 | and your program, using the @code{path} command. | |
70b88761 | 7030 | |
9a27b06e RP |
7031 | On systems with memory-mapped files, an auxiliary file |
7032 | @file{@var{filename}.syms} may hold symbol table information for | |
7033 | @var{filename}. If so, @value{GDBN} maps in the symbol table from | |
14d01801 | 7034 | @file{@var{filename}.syms}, starting up more quickly. See the |
af215b1a | 7035 | descriptions of the file options @samp{-mapped} and @samp{-readnow} |
9a27b06e | 7036 | (available on the command line, and with the commands @code{file}, |
af215b1a VM |
7037 | @code{symbol-file}, or @code{add-symbol-file}, described below), |
7038 | for more information. | |
14d01801 | 7039 | |
e0dacfd1 | 7040 | @item file |
18fae2a8 | 7041 | @code{file} with no argument makes @value{GDBN} discard any information it |
70b88761 RP |
7042 | has on both executable file and the symbol table. |
7043 | ||
70b88761 | 7044 | @kindex exec-file |
af215b1a | 7045 | @item exec-file @r{[} @var{filename} @r{]} |
70b88761 | 7046 | Specify that the program to be run (but not the symbol table) is found |
9a27b06e | 7047 | in @var{filename}. @value{GDBN} searches the environment variable @code{PATH} |
29a2b744 | 7048 | if necessary to locate your program. Omitting @var{filename} means to |
e0dacfd1 | 7049 | discard information on the executable file. |
70b88761 | 7050 | |
70b88761 | 7051 | @kindex symbol-file |
af215b1a | 7052 | @item symbol-file @r{[} @var{filename} @r{]} |
70b88761 RP |
7053 | Read symbol table information from file @var{filename}. @code{PATH} is |
7054 | searched when necessary. Use the @code{file} command to get both symbol | |
7055 | table and program to run from the same file. | |
7056 | ||
93918348 | 7057 | @code{symbol-file} with no argument clears out @value{GDBN} information on your |
70b88761 RP |
7058 | program's symbol table. |
7059 | ||
af215b1a VM |
7060 | The @code{symbol-file} command causes @value{GDBN} to forget the contents |
7061 | of its convenience variables, the value history, and all breakpoints and | |
70b88761 RP |
7062 | auto-display expressions. This is because they may contain pointers to |
7063 | the internal data recording symbols and data types, which are part of | |
18fae2a8 | 7064 | the old symbol table data being discarded inside @value{GDBN}. |
70b88761 | 7065 | |
9a27b06e | 7066 | @code{symbol-file} does not repeat if you press @key{RET} again after |
70b88761 RP |
7067 | executing it once. |
7068 | ||
9a27b06e RP |
7069 | When @value{GDBN} is configured for a particular environment, it |
7070 | understands debugging information in whatever format is the standard | |
af215b1a | 7071 | generated for that environment; you may use either a @sc{gnu} compiler, or |
14d01801 | 7072 | other compilers that adhere to the local conventions. Best results are |
af215b1a | 7073 | usually obtained from @sc{gnu} compilers; for example, using @code{@value{GCC}} |
14d01801 RP |
7074 | you can generate debugging information for optimized code. |
7075 | ||
70b88761 | 7076 | On some kinds of object files, the @code{symbol-file} command does not |
14d01801 | 7077 | normally read the symbol table in full right away. Instead, it scans |
70b88761 RP |
7078 | the symbol table quickly to find which source files and which symbols |
7079 | are present. The details are read later, one source file at a time, | |
1041a570 | 7080 | as they are needed. |
70b88761 | 7081 | |
18fae2a8 | 7082 | The purpose of this two-stage reading strategy is to make @value{GDBN} start up |
1041a570 RP |
7083 | faster. For the most part, it is invisible except for occasional |
7084 | pauses while the symbol table details for a particular source file are | |
7085 | being read. (The @code{set verbose} command can turn these pauses | |
93928b60 RP |
7086 | into messages if desired. @xref{Messages/Warnings, ,Optional warnings |
7087 | and messages}.) | |
70b88761 | 7088 | |
8c69096b RP |
7089 | We have not implemented the two-stage strategy for COFF yet. When the |
7090 | symbol table is stored in COFF format, @code{symbol-file} reads the | |
7091 | symbol table data in full right away. | |
70b88761 | 7092 | |
14d01801 RP |
7093 | @kindex readnow |
7094 | @cindex reading symbols immediately | |
7095 | @cindex symbols, reading immediately | |
7096 | @kindex mapped | |
7097 | @cindex memory-mapped symbol file | |
38962738 | 7098 | @cindex saving symbol table |
af215b1a VM |
7099 | @item symbol-file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} |
7100 | @itemx file @var{filename} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
18fae2a8 | 7101 | You can override the @value{GDBN} two-stage strategy for reading symbol |
95d5ceb9 | 7102 | tables by using the @samp{-readnow} option with any of the commands that |
18fae2a8 | 7103 | load symbol table information, if you want to be sure @value{GDBN} has the |
14d01801 RP |
7104 | entire symbol table available. |
7105 | ||
18fae2a8 | 7106 | @ifclear BARETARGET |
14d01801 | 7107 | If memory-mapped files are available on your system through the |
95d5ceb9 | 7108 | @code{mmap} system call, you can use another option, @samp{-mapped}, to |
18fae2a8 | 7109 | cause @value{GDBN} to write the symbols for your program into a reusable |
9a27b06e | 7110 | file. Future @value{GDBN} debugging sessions map in symbol information |
93918348 | 7111 | from this auxiliary symbol file (if the program has not changed), rather |
77b46d13 JG |
7112 | than spending time reading the symbol table from the executable |
7113 | program. Using the @samp{-mapped} option has the same effect as | |
18fae2a8 | 7114 | starting @value{GDBN} with the @samp{-mapped} command-line option. |
14d01801 | 7115 | |
95d5ceb9 | 7116 | You can use both options together, to make sure the auxiliary symbol |
14d01801 RP |
7117 | file has all the symbol information for your program. |
7118 | ||
7119 | The auxiliary symbol file for a program called @var{myprog} is called | |
7120 | @samp{@var{myprog}.syms}. Once this file exists (so long as it is newer | |
9a27b06e | 7121 | than the corresponding executable), @value{GDBN} always attempts to use |
14d01801 RP |
7122 | it when you debug @var{myprog}; no special options or commands are |
7123 | needed. | |
93918348 RP |
7124 | |
7125 | The @file{.syms} file is specific to the host machine where you run | |
34ae25cd | 7126 | @value{GDBN}. It holds an exact image of the internal @value{GDBN} |
93918348 RP |
7127 | symbol table. It cannot be shared across multiple host platforms. |
7128 | ||
14d01801 RP |
7129 | @c FIXME: for now no mention of directories, since this seems to be in |
7130 | @c flux. 13mar1992 status is that in theory GDB would look either in | |
7131 | @c current dir or in same dir as myprog; but issues like competing | |
7132 | @c GDB's, or clutter in system dirs, mean that in practice right now | |
7133 | @c only current dir is used. FFish says maybe a special GDB hierarchy | |
7134 | @c (eg rooted in val of env var GDBSYMS) could exist for mappable symbol | |
7135 | @c files. | |
70b88761 | 7136 | |
70b88761 RP |
7137 | @kindex core |
7138 | @kindex core-file | |
af215b1a | 7139 | @item core-file @r{[} @var{filename} @r{]} |
70b88761 RP |
7140 | Specify the whereabouts of a core dump file to be used as the ``contents |
7141 | of memory''. Traditionally, core files contain only some parts of the | |
18fae2a8 | 7142 | address space of the process that generated them; @value{GDBN} can access the |
70b88761 RP |
7143 | executable file itself for other parts. |
7144 | ||
7145 | @code{core-file} with no argument specifies that no core file is | |
7146 | to be used. | |
7147 | ||
7148 | Note that the core file is ignored when your program is actually running | |
18fae2a8 | 7149 | under @value{GDBN}. So, if you have been running your program and you wish to |
70b88761 RP |
7150 | debug a core file instead, you must kill the subprocess in which the |
7151 | program is running. To do this, use the @code{kill} command | |
93928b60 | 7152 | (@pxref{Kill Process, ,Killing the child process}). |
18fae2a8 | 7153 | @end ifclear |
70b88761 | 7154 | |
af215b1a | 7155 | @kindex load @var{filename} |
70b88761 | 7156 | @item load @var{filename} |
18fae2a8 | 7157 | @ifset GENERIC |
70b88761 | 7158 | Depending on what remote debugging facilities are configured into |
18fae2a8 | 7159 | @value{GDBN}, the @code{load} command may be available. Where it exists, it |
70b88761 RP |
7160 | is meant to make @var{filename} (an executable) available for debugging |
7161 | on the remote system---by downloading, or dynamic linking, for example. | |
93918348 | 7162 | @code{load} also records the @var{filename} symbol table in @value{GDBN}, like |
70b88761 RP |
7163 | the @code{add-symbol-file} command. |
7164 | ||
ed447b95 RP |
7165 | If your @value{GDBN} does not have a @code{load} command, attempting to |
7166 | execute it gets the error message ``@code{You can't do that when your | |
7167 | target is @dots{}}'' | |
18fae2a8 | 7168 | @end ifset |
70b88761 | 7169 | |
99d1da6a | 7170 | The file is loaded at whatever address is specified in the executable. |
22b5dba5 RP |
7171 | For some object file formats, you can specify the load address when you |
7172 | link the program; for other formats, like a.out, the object file format | |
7173 | specifies a fixed address. | |
7174 | @c FIXME! This would be a good place for an xref to the GNU linker doc. | |
99d1da6a | 7175 | |
18fae2a8 | 7176 | @ifset VXWORKS |
9a27b06e | 7177 | On VxWorks, @code{load} links @var{filename} dynamically on the |
18fae2a8 RP |
7178 | current target system as well as adding its symbols in @value{GDBN}. |
7179 | @end ifset | |
70b88761 | 7180 | |
a64a6c2b | 7181 | @ifset I960 |
70b88761 | 7182 | @cindex download to Nindy-960 |
9a27b06e RP |
7183 | With the Nindy interface to an Intel 960 board, @code{load} |
7184 | downloads @var{filename} to the 960 as well as adding its symbols in | |
18fae2a8 RP |
7185 | @value{GDBN}. |
7186 | @end ifset | |
70b88761 | 7187 | |
a64a6c2b | 7188 | @ifset H8 |
1d7c3357 RP |
7189 | @cindex download to H8/300 or H8/500 |
7190 | @cindex H8/300 or H8/500 download | |
a64a6c2b RP |
7191 | @cindex download to Hitachi SH |
7192 | @cindex Hitachi SH download | |
72545cc6 | 7193 | When you select remote debugging to a Hitachi SH, H8/300, or H8/500 board |
a64a6c2b | 7194 | (@pxref{Hitachi Remote,,@value{GDBN} and Hitachi Microprocessors}), |
1d7c3357 RP |
7195 | the @code{load} command downloads your program to the Hitachi board and also |
7196 | opens it as the current executable target for @value{GDBN} on your host | |
7197 | (like the @code{file} command). | |
18fae2a8 | 7198 | @end ifset |
c7cb8acb | 7199 | |
9a27b06e | 7200 | @code{load} does not repeat if you press @key{RET} again after using it. |
70b88761 | 7201 | |
18fae2a8 | 7202 | @ifclear BARETARGET |
70b88761 RP |
7203 | @kindex add-symbol-file |
7204 | @cindex dynamic linking | |
af215b1a VM |
7205 | @item add-symbol-file @var{filename} @var{address} |
7206 | @itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{]} @r{[} -mapped @r{]} | |
70b88761 | 7207 | The @code{add-symbol-file} command reads additional symbol table information |
b80282d5 | 7208 | from the file @var{filename}. You would use this command when @var{filename} |
70b88761 RP |
7209 | has been dynamically loaded (by some other means) into the program that |
7210 | is running. @var{address} should be the memory address at which the | |
18fae2a8 | 7211 | file has been loaded; @value{GDBN} cannot figure this out for itself. |
d55320a0 | 7212 | You can specify @var{address} as an expression. |
70b88761 RP |
7213 | |
7214 | The symbol table of the file @var{filename} is added to the symbol table | |
7215 | originally read with the @code{symbol-file} command. You can use the | |
7216 | @code{add-symbol-file} command any number of times; the new symbol data thus | |
7217 | read keeps adding to the old. To discard all old symbol data instead, | |
e251e767 | 7218 | use the @code{symbol-file} command. |
70b88761 | 7219 | |
9a27b06e | 7220 | @code{add-symbol-file} does not repeat if you press @key{RET} after using it. |
70b88761 | 7221 | |
95d5ceb9 | 7222 | You can use the @samp{-mapped} and @samp{-readnow} options just as with |
18fae2a8 | 7223 | the @code{symbol-file} command, to change how @value{GDBN} manages the symbol |
0f153e74 | 7224 | table information for @var{filename}. |
af215b1a VM |
7225 | |
7226 | @kindex add-shared-symbol-file | |
7227 | @item add-shared-symbol-file | |
7228 | The @code{add-shared-symbol-file} command can be used only under Harris' CXUX | |
7229 | operating system for the Motorola 88k. @value{GDBN} automatically looks for | |
7230 | shared libraries, however if @value{GDBN} does not find yours, you can run | |
7231 | @code{add-shared-symbol-file}. It takes no arguments. | |
18fae2a8 | 7232 | @end ifclear |
95d5ceb9 | 7233 | |
af215b1a VM |
7234 | @kindex section |
7235 | @item section | |
7236 | The @code{section} command changes the base address of section SECTION of | |
7237 | the exec file to ADDR. This can be used if the exec file does not contain | |
7238 | section addresses, (such as in the a.out format), or when the addresses | |
7239 | specified in the file itself are wrong. Each section must be changed | |
7240 | separately. The ``info files'' command lists all the sections and their | |
7241 | addresses. | |
7242 | ||
70b88761 RP |
7243 | @kindex info files |
7244 | @kindex info target | |
af215b1a VM |
7245 | @item info files |
7246 | @itemx info target | |
1041a570 | 7247 | @code{info files} and @code{info target} are synonymous; both print |
1d7c3357 RP |
7248 | the current target (@pxref{Targets, ,Specifying a Debugging Target}), |
7249 | including the | |
7250 | @ifclear BARETARGET | |
7251 | names of the executable and core dump files | |
7252 | @end ifclear | |
7253 | @ifset BARETARGET | |
7254 | name of the executable file | |
7255 | @end ifset | |
7256 | currently in use by @value{GDBN}, and the files from which symbols were | |
a4ae3702 | 7257 | loaded. The command @code{help target} lists all possible targets |
1d7c3357 | 7258 | rather than current ones. |
70b88761 RP |
7259 | @end table |
7260 | ||
7261 | All file-specifying commands allow both absolute and relative file names | |
b550c03a | 7262 | as arguments. @value{GDBN} always converts the file name to an absolute file |
70b88761 RP |
7263 | name and remembers it that way. |
7264 | ||
18fae2a8 | 7265 | @ifclear BARETARGET |
70b88761 | 7266 | @cindex shared libraries |
9a27b06e | 7267 | @value{GDBN} supports SunOS, SVr4, Irix 5, and IBM RS/6000 shared libraries. |
18fae2a8 | 7268 | @value{GDBN} automatically loads symbol definitions from shared libraries |
77b46d13 | 7269 | when you use the @code{run} command, or when you examine a core file. |
9a27b06e | 7270 | (Before you issue the @code{run} command, @value{GDBN} does not understand |
77b46d13 JG |
7271 | references to a function in a shared library, however---unless you are |
7272 | debugging a core file). | |
9a27b06e RP |
7273 | @c FIXME: some @value{GDBN} release may permit some refs to undef |
7274 | @c FIXME...symbols---eg in a break cmd---assuming they are from a shared | |
7275 | @c FIXME...lib; check this from time to time when updating manual | |
70b88761 RP |
7276 | |
7277 | @table @code | |
70b88761 RP |
7278 | @kindex info sharedlibrary |
7279 | @kindex info share | |
af215b1a VM |
7280 | @item info share |
7281 | @itemx info sharedlibrary | |
c338a2fd | 7282 | Print the names of the shared libraries which are currently loaded. |
70b88761 | 7283 | |
c338a2fd RP |
7284 | @kindex sharedlibrary |
7285 | @kindex share | |
af215b1a VM |
7286 | @item sharedlibrary @var{regex} |
7287 | @itemx share @var{regex} | |
7288 | ||
f886dc0f SS |
7289 | Load shared object library symbols for files matching a |
7290 | Unix regular expression. | |
7291 | As with files loaded automatically, it only loads shared libraries | |
6b51acad RP |
7292 | required by your program for a core file or after typing @code{run}. If |
7293 | @var{regex} is omitted all shared libraries required by your program are | |
7294 | loaded. | |
c338a2fd | 7295 | @end table |
18fae2a8 | 7296 | @end ifclear |
70b88761 | 7297 | |
4eb4cf57 | 7298 | @node Symbol Errors |
93928b60 | 7299 | @section Errors reading symbol files |
1041a570 | 7300 | |
9a27b06e | 7301 | While reading a symbol file, @value{GDBN} occasionally encounters problems, |
1041a570 | 7302 | such as symbol types it does not recognize, or known bugs in compiler |
18fae2a8 | 7303 | output. By default, @value{GDBN} does not notify you of such problems, since |
1041a570 RP |
7304 | they are relatively common and primarily of interest to people |
7305 | debugging compilers. If you are interested in seeing information | |
18fae2a8 | 7306 | about ill-constructed symbol tables, you can either ask @value{GDBN} to print |
b80282d5 | 7307 | only one message about each such type of problem, no matter how many |
18fae2a8 | 7308 | times the problem occurs; or you can ask @value{GDBN} to print more messages, |
1041a570 | 7309 | to see how many times the problems occur, with the @code{set |
93928b60 RP |
7310 | complaints} command (@pxref{Messages/Warnings, ,Optional warnings and |
7311 | messages}). | |
70b88761 | 7312 | |
d55320a0 | 7313 | The messages currently printed, and their meanings, include: |
70b88761 RP |
7314 | |
7315 | @table @code | |
7316 | @item inner block not inside outer block in @var{symbol} | |
7317 | ||
7318 | The symbol information shows where symbol scopes begin and end | |
7319 | (such as at the start of a function or a block of statements). This | |
7320 | error indicates that an inner scope block is not fully contained | |
e251e767 | 7321 | in its outer scope blocks. |
70b88761 | 7322 | |
18fae2a8 | 7323 | @value{GDBN} circumvents the problem by treating the inner block as if it had |
70b88761 RP |
7324 | the same scope as the outer block. In the error message, @var{symbol} |
7325 | may be shown as ``@code{(don't know)}'' if the outer block is not a | |
7326 | function. | |
7327 | ||
7328 | @item block at @var{address} out of order | |
7329 | ||
e251e767 | 7330 | The symbol information for symbol scope blocks should occur in |
70b88761 | 7331 | order of increasing addresses. This error indicates that it does not |
e251e767 | 7332 | do so. |
70b88761 | 7333 | |
9a27b06e | 7334 | @value{GDBN} does not circumvent this problem, and has trouble |
ed447b95 RP |
7335 | locating symbols in the source file whose symbols it is reading. (You |
7336 | can often determine what source file is affected by specifying | |
93928b60 RP |
7337 | @code{set verbose on}. @xref{Messages/Warnings, ,Optional warnings and |
7338 | messages}.) | |
70b88761 RP |
7339 | |
7340 | @item bad block start address patched | |
7341 | ||
7342 | The symbol information for a symbol scope block has a start address | |
7343 | smaller than the address of the preceding source line. This is known | |
e251e767 | 7344 | to occur in the SunOS 4.1.1 (and earlier) C compiler. |
70b88761 | 7345 | |
18fae2a8 | 7346 | @value{GDBN} circumvents the problem by treating the symbol scope block as |
70b88761 RP |
7347 | starting on the previous source line. |
7348 | ||
70b88761 RP |
7349 | @item bad string table offset in symbol @var{n} |
7350 | ||
7351 | @cindex foo | |
7352 | Symbol number @var{n} contains a pointer into the string table which is | |
e251e767 | 7353 | larger than the size of the string table. |
70b88761 | 7354 | |
18fae2a8 | 7355 | @value{GDBN} circumvents the problem by considering the symbol to have the |
70b88761 RP |
7356 | name @code{foo}, which may cause other problems if many symbols end up |
7357 | with this name. | |
7358 | ||
7359 | @item unknown symbol type @code{0x@var{nn}} | |
7360 | ||
18fae2a8 | 7361 | The symbol information contains new data types that @value{GDBN} does not yet |
70b88761 | 7362 | know how to read. @code{0x@var{nn}} is the symbol type of the misunderstood |
e251e767 | 7363 | information, in hexadecimal. |
70b88761 | 7364 | |
18fae2a8 | 7365 | @value{GDBN} circumvents the error by ignoring this symbol information. This |
9a27b06e RP |
7366 | usually allows you to debug your program, though certain symbols |
7367 | are not accessible. If you encounter such a problem and feel like | |
18fae2a8 | 7368 | debugging it, you can debug @code{@value{GDBP}} with itself, breakpoint on |
70b88761 RP |
7369 | @code{complain}, then go up to the function @code{read_dbx_symtab} and |
7370 | examine @code{*bufp} to see the symbol. | |
7371 | ||
7372 | @item stub type has NULL name | |
1d7c3357 RP |
7373 | @value{GDBN} could not find the full definition for |
7374 | @ifclear CONLY | |
7375 | a struct or class. | |
7376 | @end ifclear | |
7377 | @ifset CONLY | |
7378 | a struct. | |
7379 | @end ifset | |
70b88761 | 7380 | |
1d7c3357 | 7381 | @ifclear CONLY |
440d9834 | 7382 | @item const/volatile indicator missing (ok if using g++ v1.x), got@dots{} |
70b88761 RP |
7383 | |
7384 | The symbol information for a C++ member function is missing some | |
440d9834 RP |
7385 | information that recent versions of the compiler should have output |
7386 | for it. | |
1d7c3357 | 7387 | @end ifclear |
70b88761 | 7388 | |
440d9834 | 7389 | @item info mismatch between compiler and debugger |
70b88761 | 7390 | |
18fae2a8 | 7391 | @value{GDBN} could not parse a type specification output by the compiler. |
70b88761 RP |
7392 | @end table |
7393 | ||
4eb4cf57 | 7394 | @node Targets |
e251e767 | 7395 | @chapter Specifying a Debugging Target |
70b88761 RP |
7396 | @cindex debugging target |
7397 | @kindex target | |
1041a570 | 7398 | |
cedaf8bc | 7399 | A @dfn{target} is the execution environment occupied by your program. |
18fae2a8 RP |
7400 | @ifclear BARETARGET |
7401 | Often, @value{GDBN} runs in the same host environment as your program; in | |
1041a570 RP |
7402 | that case, the debugging target is specified as a side effect when you |
7403 | use the @code{file} or @code{core} commands. When you need more | |
18fae2a8 | 7404 | flexibility---for example, running @value{GDBN} on a physically separate |
1041a570 | 7405 | host, or controlling a standalone system over a serial port or a |
0f153e74 | 7406 | realtime system over a TCP/IP connection---you |
18fae2a8 RP |
7407 | @end ifclear |
7408 | @ifset BARETARGET | |
0f153e74 | 7409 | You |
18fae2a8 | 7410 | @end ifset |
0f153e74 | 7411 | can use the @code{target} command to specify one of the target types |
93928b60 RP |
7412 | configured for @value{GDBN} (@pxref{Target Commands, ,Commands for managing |
7413 | targets}). | |
70b88761 RP |
7414 | |
7415 | @menu | |
ed447b95 RP |
7416 | * Active Targets:: Active targets |
7417 | * Target Commands:: Commands for managing targets | |
7418 | * Remote:: Remote debugging | |
70b88761 RP |
7419 | @end menu |
7420 | ||
4eb4cf57 | 7421 | @node Active Targets |
93928b60 | 7422 | @section Active targets |
70b88761 RP |
7423 | @cindex stacking targets |
7424 | @cindex active targets | |
7425 | @cindex multiple targets | |
7426 | ||
18fae2a8 | 7427 | @ifclear BARETARGET |
cedaf8bc | 7428 | There are three classes of targets: processes, core files, and |
18fae2a8 | 7429 | executable files. @value{GDBN} can work concurrently on up to three active |
cedaf8bc RP |
7430 | targets, one in each class. This allows you to (for example) start a |
7431 | process and inspect its activity without abandoning your work on a core | |
7432 | file. | |
70b88761 | 7433 | |
ed447b95 | 7434 | For example, if you execute @samp{gdb a.out}, then the executable file |
cedaf8bc RP |
7435 | @code{a.out} is the only active target. If you designate a core file as |
7436 | well---presumably from a prior run that crashed and coredumped---then | |
9a27b06e | 7437 | @value{GDBN} has two active targets and uses them in tandem, looking |
cedaf8bc RP |
7438 | first in the corefile target, then in the executable file, to satisfy |
7439 | requests for memory addresses. (Typically, these two classes of target | |
29a2b744 | 7440 | are complementary, since core files contain only a program's |
cedaf8bc RP |
7441 | read-write memory---variables and so on---plus machine status, while |
7442 | executable files contain only the program text and initialized data.) | |
18fae2a8 | 7443 | @end ifclear |
cedaf8bc RP |
7444 | |
7445 | When you type @code{run}, your executable file becomes an active process | |
18fae2a8 | 7446 | target as well. When a process target is active, all @value{GDBN} commands |
0f153e74 | 7447 | requesting memory addresses refer to that target; addresses in an |
18fae2a8 | 7448 | @ifclear BARETARGET |
0f153e74 | 7449 | active core file or |
18fae2a8 | 7450 | @end ifclear |
0f153e74 | 7451 | executable file target are obscured while the process |
cedaf8bc RP |
7452 | target is active. |
7453 | ||
18fae2a8 | 7454 | @ifset BARETARGET |
4eb4cf57 | 7455 | Use the @code{exec-file} command to select a |
93928b60 RP |
7456 | new executable target (@pxref{Files, ,Commands to specify |
7457 | files}). | |
18fae2a8 RP |
7458 | @end ifset |
7459 | @ifclear BARETARGET | |
1041a570 | 7460 | Use the @code{core-file} and @code{exec-file} commands to select a |
93928b60 RP |
7461 | new core file or executable target (@pxref{Files, ,Commands to specify |
7462 | files}). To specify as a target a process that is already running, use | |
1041a570 | 7463 | the @code{attach} command (@pxref{Attach, ,Debugging an |
93928b60 | 7464 | already-running process}). |
18fae2a8 | 7465 | @end ifclear |
70b88761 | 7466 | |
4eb4cf57 | 7467 | @node Target Commands |
93928b60 | 7468 | @section Commands for managing targets |
70b88761 RP |
7469 | |
7470 | @table @code | |
7471 | @item target @var{type} @var{parameters} | |
1d7c3357 RP |
7472 | Connects the @value{GDBN} host environment to a target |
7473 | @ifset BARETARGET | |
7474 | machine. | |
7475 | @end ifset | |
7476 | @ifclear BARETARGET | |
7477 | machine or process. A target is typically a protocol for talking to | |
7478 | debugging facilities. You use the argument @var{type} to specify the | |
7479 | type or protocol of the target machine. | |
70b88761 RP |
7480 | |
7481 | Further @var{parameters} are interpreted by the target protocol, but | |
7482 | typically include things like device names or host names to connect | |
e251e767 | 7483 | with, process numbers, and baud rates. |
1d7c3357 | 7484 | @end ifclear |
70b88761 | 7485 | |
9a27b06e | 7486 | The @code{target} command does not repeat if you press @key{RET} again |
70b88761 RP |
7487 | after executing the command. |
7488 | ||
70b88761 | 7489 | @kindex help target |
af215b1a | 7490 | @item help target |
70b88761 RP |
7491 | Displays the names of all targets available. To display targets |
7492 | currently selected, use either @code{info target} or @code{info files} | |
93928b60 | 7493 | (@pxref{Files, ,Commands to specify files}). |
70b88761 RP |
7494 | |
7495 | @item help target @var{name} | |
7496 | Describe a particular target, including any parameters necessary to | |
7497 | select it. | |
af215b1a VM |
7498 | |
7499 | @kindex set gnutarget | |
7500 | @item set gnutarget @var{args} | |
7501 | @value{GDBN}uses its own library BFD to read your files. @value{GDBN} | |
7502 | knows whether it is reading an @dfn{executable}, | |
7503 | a @dfn{core}, or a @dfn{.o} file, however you can specify the file format | |
7504 | with the @code{set gnutarget} command. Unlike most @code{target} commands, | |
7505 | with @code{gnutarget} the @code{target} refers to a program, not a machine. | |
7506 | ||
7507 | @emph{Warning:} To specify a file format with @code{set gnutarget}, | |
7508 | you must know the actual BFD name. | |
7509 | ||
7510 | @noindent @xref{Files, , Commands to specify files}. | |
7511 | ||
7512 | @kindex show gnutarget | |
7513 | @item show gnutarget | |
7514 | Use the @code{show gnutarget} command to display what file format | |
7515 | @code{gnutarget} is set to read. If you have not set @code{gnutarget}, | |
7516 | @value{GDBN} will determine the file format for each file automatically | |
7517 | and @code{show gnutarget} displays @code{The current BDF target is "auto"}. | |
70b88761 RP |
7518 | @end table |
7519 | ||
c7cb8acb | 7520 | Here are some common targets (available, or not, depending on the GDB |
70b88761 RP |
7521 | configuration): |
7522 | ||
7523 | @table @code | |
70b88761 | 7524 | @kindex target exec |
af215b1a | 7525 | @item target exec @var{program} |
fe715d06 RP |
7526 | An executable file. @samp{target exec @var{program}} is the same as |
7527 | @samp{exec-file @var{program}}. | |
70b88761 | 7528 | |
1d7c3357 | 7529 | @ifclear BARETARGET |
70b88761 | 7530 | @kindex target core |
af215b1a | 7531 | @item target core @var{filename} |
70b88761 RP |
7532 | A core dump file. @samp{target core @var{filename}} is the same as |
7533 | @samp{core-file @var{filename}}. | |
1d7c3357 | 7534 | @end ifclear |
70b88761 | 7535 | |
18fae2a8 | 7536 | @ifset REMOTESTUB |
70b88761 | 7537 | @kindex target remote |
af215b1a | 7538 | @item target remote @var{dev} |
c7cb8acb | 7539 | Remote serial target in GDB-specific protocol. The argument @var{dev} |
70b88761 | 7540 | specifies what serial device to use for the connection (e.g. |
af215b1a VM |
7541 | @file{/dev/ttya}). @xref{Remote, ,Remote debugging}. @code{target remote} |
7542 | now supports the @code{load} command. This is only useful if you have | |
7543 | some other way of getting the stub to the target system, and you can put | |
7544 | it somewhere in memory where it won't get clobbered by the download. | |
18fae2a8 | 7545 | @end ifset |
70b88761 | 7546 | |
fe715d06 | 7547 | @ifset SIMS |
fe715d06 | 7548 | @kindex target sim |
af215b1a | 7549 | @item target sim |
fe715d06 RP |
7550 | CPU simulator. @xref{Simulator,,Simulated CPU Target}. |
7551 | @end ifset | |
7552 | ||
a64a6c2b | 7553 | @ifset AMD29K |
fe715d06 | 7554 | @kindex target udi |
af215b1a | 7555 | @item target udi @var{keyword} |
fe715d06 RP |
7556 | Remote AMD29K target, using the AMD UDI protocol. The @var{keyword} |
7557 | argument specifies which 29K board or simulator to use. @xref{UDI29K | |
b1955f0b | 7558 | Remote,,The UDI protocol for AMD29K}. |
fe715d06 | 7559 | |
70b88761 | 7560 | @kindex target amd-eb |
af215b1a | 7561 | @item target amd-eb @var{dev} @var{speed} @var{PROG} |
70b88761 RP |
7562 | @cindex AMD EB29K |
7563 | Remote PC-resident AMD EB29K board, attached over serial lines. | |
7564 | @var{dev} is the serial device, as for @code{target remote}; | |
7565 | @var{speed} allows you to specify the linespeed; and @var{PROG} is the | |
7566 | name of the program to be debugged, as it appears to DOS on the PC. | |
b1955f0b | 7567 | @xref{EB29K Remote, ,The EBMON protocol for AMD29K}. |
77fe5411 | 7568 | |
18fae2a8 | 7569 | @end ifset |
a64a6c2b | 7570 | @ifset H8 |
c7cb8acb | 7571 | @kindex target hms |
af215b1a | 7572 | @item target hms @var{dev} |
72545cc6 | 7573 | A Hitachi SH, H8/300, or H8/500 board, attached via serial line to your host. |
a64a6c2b | 7574 | @ifclear H8EXCLUSIVE |
a64a6c2b RP |
7575 | Use special commands @code{device} and @code{speed} to control the serial |
7576 | line and the communications speed used. | |
7577 | @end ifclear | |
7578 | @xref{Hitachi Remote,,@value{GDBN} and Hitachi Microprocessors}. | |
c7cb8acb | 7579 | |
18fae2a8 | 7580 | @end ifset |
a64a6c2b | 7581 | @ifset I960 |
70b88761 | 7582 | @kindex target nindy |
af215b1a | 7583 | @item target nindy @var{devicename} |
70b88761 RP |
7584 | An Intel 960 board controlled by a Nindy Monitor. @var{devicename} is |
7585 | the name of the serial device to use for the connection, e.g. | |
ed447b95 | 7586 | @file{/dev/ttya}. @xref{i960-Nindy Remote, ,@value{GDBN} with a remote i960 (Nindy)}. |
70b88761 | 7587 | |
18fae2a8 | 7588 | @end ifset |
a64a6c2b | 7589 | @ifset ST2000 |
77fe5411 | 7590 | @kindex target st2000 |
af215b1a | 7591 | @item target st2000 @var{dev} @var{speed} |
77fe5411 RP |
7592 | A Tandem ST2000 phone switch, running Tandem's STDBUG protocol. @var{dev} |
7593 | is the name of the device attached to the ST2000 serial line; | |
7594 | @var{speed} is the communication line speed. The arguments are not used | |
18fae2a8 RP |
7595 | if @value{GDBN} is configured to connect to the ST2000 using TCP or Telnet. |
7596 | @xref{ST2000 Remote,,@value{GDBN} with a Tandem ST2000}. | |
18fae2a8 | 7597 | @end ifset |
af215b1a | 7598 | |
18fae2a8 | 7599 | @ifset VXWORKS |
70b88761 | 7600 | @kindex target vxworks |
af215b1a | 7601 | @item target vxworks @var{machinename} |
70b88761 RP |
7602 | A VxWorks system, attached via TCP/IP. The argument @var{machinename} |
7603 | is the target system's machine name or IP address. | |
18fae2a8 RP |
7604 | @xref{VxWorks Remote, ,@value{GDBN} and VxWorks}. |
7605 | @end ifset | |
af215b1a | 7606 | |
d390cad1 SS |
7607 | @kindex target bug |
7608 | @item target bug @var{dev} | |
7609 | BUG monitor, running on a MVME187 (m88k) board. | |
7610 | ||
af215b1a VM |
7611 | @kindex target cpu32bug |
7612 | @item target cpu32bug @var{dev} | |
7613 | CPU32BUG monitor, running on a CPU32 (M68K) board. | |
7614 | ||
7615 | @kindex target op50n | |
7616 | @item target op50n @var{dev} | |
7617 | OP50N monitor, running on an OKI HPPA board. | |
7618 | ||
7619 | @kindex target w89k | |
7620 | @item target w89k @var{dev} | |
7621 | W89K monitor, running on a Winbond HPPA board. | |
7622 | ||
7623 | @kindex target est | |
7624 | @item target est @var{dev} | |
7625 | EST-300 ICE monitor, running on a CPU32 (M68K) board. | |
7626 | ||
7627 | @kindex target rom68k | |
7628 | @item target rom68k @var{dev} | |
7629 | ROM 68K monitor, running on an IDP board. | |
7630 | ||
7631 | @kindex target array | |
7632 | @item target array @var{dev} | |
7633 | Array Tech LSI33K RAID controller board. | |
7634 | ||
7635 | @kindex target sparclite | |
7636 | @item target sparclite @var{dev} | |
7637 | Fujitsu sparclite boards, used only for the purpose of loading. | |
7638 | You must use an additional command to debug the program. | |
7639 | For example: target remote @var{dev} using @value{GDBN} standard | |
7640 | remote protocol. | |
70b88761 RP |
7641 | @end table |
7642 | ||
18fae2a8 | 7643 | @ifset GENERIC |
af215b1a VM |
7644 | Different targets are available on different configurations of @value{GDBN}; |
7645 | your configuration may have more or fewer targets. | |
18fae2a8 | 7646 | @end ifset |
70b88761 | 7647 | |
af215b1a VM |
7648 | @section Choosing target byte order |
7649 | @cindex choosing target byte order | |
7650 | @cindex target byte order | |
7651 | @kindex set endian big | |
7652 | @kindex set endian little | |
7653 | @kindex set endian auto | |
7654 | @kindex show endian | |
7655 | ||
7656 | You can now choose which byte order to use with a target system. | |
7657 | Use the @code{set endian big} and @code{set endian little} commands. | |
7658 | Use the @code{set endian auto} command to instruct | |
7659 | @value{GDBN} to use the byte order associated with the executable. | |
7660 | You can see the current setting for byte order with the @code{show endian} | |
7661 | command. | |
7662 | ||
7663 | @emph{Warning:} Currently, only embedded MIPS configurations support | |
7664 | dynamic selection of target byte order. | |
7665 | ||
4eb4cf57 | 7666 | @node Remote |
93928b60 | 7667 | @section Remote debugging |
70b88761 RP |
7668 | @cindex remote debugging |
7669 | ||
29a2b744 | 7670 | If you are trying to debug a program running on a machine that cannot run |
af215b1a VM |
7671 | @value{GDBN} in the usual way, it is often useful to use remote debugging. |
7672 | For example, you might use remote debugging on an operating system kernel, | |
7673 | or on a small system which does not have a general purpose operating system | |
e251e767 | 7674 | powerful enough to run a full-featured debugger. |
70b88761 | 7675 | |
af215b1a | 7676 | Some configurations of @value{GDBN} have special serial or TCP/IP interfaces |
70b88761 | 7677 | to make this work with particular debugging targets. In addition, |
af215b1a VM |
7678 | @value{GDBN} comes with a generic serial protocol (specific to @value{GDBN}, |
7679 | but not specific to any particular target system) which you can use if you | |
9a27b06e | 7680 | write the remote stubs---the code that runs on the remote system to |
af215b1a | 7681 | communicate with @value{GDBN}. |
70b88761 | 7682 | |
70b88761 | 7683 | Other remote targets may be available in your |
af215b1a | 7684 | configuration of @value{GDBN}; use @code{help target} to list them. |
70b88761 | 7685 | |
18fae2a8 RP |
7686 | @ifset GENERIC |
7687 | @c Text on starting up GDB in various specific cases; it goes up front | |
7688 | @c in manuals configured for any of those particular situations, here | |
7689 | @c otherwise. | |
18fae2a8 RP |
7690 | @menu |
7691 | @ifset REMOTESTUB | |
7692 | * Remote Serial:: @value{GDBN} remote serial protocol | |
7693 | @end ifset | |
a64a6c2b | 7694 | @ifset I960 |
18fae2a8 RP |
7695 | * i960-Nindy Remote:: @value{GDBN} with a remote i960 (Nindy) |
7696 | @end ifset | |
a64a6c2b | 7697 | @ifset AMD29K |
b1955f0b RP |
7698 | * UDI29K Remote:: The UDI protocol for AMD29K |
7699 | * EB29K Remote:: The EBMON protocol for AMD29K | |
18fae2a8 RP |
7700 | @end ifset |
7701 | @ifset VXWORKS | |
7702 | * VxWorks Remote:: @value{GDBN} and VxWorks | |
7703 | @end ifset | |
a64a6c2b | 7704 | @ifset ST2000 |
18fae2a8 RP |
7705 | * ST2000 Remote:: @value{GDBN} with a Tandem ST2000 |
7706 | @end ifset | |
a64a6c2b RP |
7707 | @ifset H8 |
7708 | * Hitachi Remote:: @value{GDBN} and Hitachi Microprocessors | |
18fae2a8 | 7709 | @end ifset |
34ae25cd RP |
7710 | @ifset MIPS |
7711 | * MIPS Remote:: @value{GDBN} and MIPS boards | |
7712 | @end ifset | |
146ff252 DE |
7713 | @ifset SPARCLET |
7714 | * Sparclet Remote:: @value{GDBN} and Sparclet boards | |
7715 | @end ifset | |
fe715d06 RP |
7716 | @ifset SIMS |
7717 | * Simulator:: Simulated CPU target | |
18fae2a8 RP |
7718 | @end ifset |
7719 | @end menu | |
70b88761 | 7720 | |
4af6d502 | 7721 | @include remote.texi |
18fae2a8 RP |
7722 | @end ifset |
7723 | ||
7724 | @node Controlling GDB | |
7725 | @chapter Controlling @value{GDBN} | |
70b88761 | 7726 | |
93918348 | 7727 | You can alter the way @value{GDBN} interacts with you by using |
18fae2a8 | 7728 | the @code{set} command. For commands controlling how @value{GDBN} displays |
af215b1a VM |
7729 | data, @pxref{Print Settings, ,Print settings}; other settings are described |
7730 | here. | |
70b88761 RP |
7731 | |
7732 | @menu | |
b80282d5 | 7733 | * Prompt:: Prompt |
ed447b95 RP |
7734 | * Editing:: Command editing |
7735 | * History:: Command history | |
7736 | * Screen Size:: Screen size | |
b80282d5 | 7737 | * Numbers:: Numbers |
ed447b95 | 7738 | * Messages/Warnings:: Optional warnings and messages |
70b88761 RP |
7739 | @end menu |
7740 | ||
4eb4cf57 | 7741 | @node Prompt |
70b88761 | 7742 | @section Prompt |
af215b1a | 7743 | |
70b88761 | 7744 | @cindex prompt |
1041a570 | 7745 | |
18fae2a8 RP |
7746 | @value{GDBN} indicates its readiness to read a command by printing a string |
7747 | called the @dfn{prompt}. This string is normally @samp{(@value{GDBP})}. You | |
70b88761 | 7748 | can change the prompt string with the @code{set prompt} command. For |
18fae2a8 | 7749 | instance, when debugging @value{GDBN} with @value{GDBN}, it is useful to change |
af215b1a VM |
7750 | the prompt in one of the @value{GDBN} sessions so that you can always tell |
7751 | which one you are talking to. | |
7752 | ||
7753 | @emph{Note:} @code{set prompt} no longer adds a space for you after the | |
7754 | prompt you set. This allows you to set a prompt which ends in a space | |
7755 | or a prompt that does not. | |
70b88761 RP |
7756 | |
7757 | @table @code | |
70b88761 | 7758 | @kindex set prompt |
af215b1a | 7759 | @item set prompt @var{newprompt} |
18fae2a8 | 7760 | Directs @value{GDBN} to use @var{newprompt} as its prompt string henceforth. |
af215b1a | 7761 | |
70b88761 RP |
7762 | @kindex show prompt |
7763 | @item show prompt | |
7764 | Prints a line of the form: @samp{Gdb's prompt is: @var{your-prompt}} | |
7765 | @end table | |
7766 | ||
4eb4cf57 | 7767 | @node Editing |
93928b60 | 7768 | @section Command editing |
70b88761 RP |
7769 | @cindex readline |
7770 | @cindex command line editing | |
1041a570 | 7771 | |
18fae2a8 | 7772 | @value{GDBN} reads its input commands via the @dfn{readline} interface. This |
af215b1a VM |
7773 | @sc{gnu} library provides consistent behavior for programs which provide a |
7774 | command line interface to the user. Advantages are @sc{gnu} Emacs-style | |
7775 | or @dfn{vi}-style inline editing of commands, @code{csh}-like history | |
70b88761 RP |
7776 | substitution, and a storage and recall of command history across |
7777 | debugging sessions. | |
7778 | ||
18fae2a8 | 7779 | You may control the behavior of command line editing in @value{GDBN} with the |
e251e767 | 7780 | command @code{set}. |
70b88761 RP |
7781 | |
7782 | @table @code | |
7783 | @kindex set editing | |
7784 | @cindex editing | |
7785 | @item set editing | |
7786 | @itemx set editing on | |
7787 | Enable command line editing (enabled by default). | |
7788 | ||
7789 | @item set editing off | |
7790 | Disable command line editing. | |
7791 | ||
7792 | @kindex show editing | |
7793 | @item show editing | |
7794 | Show whether command line editing is enabled. | |
7795 | @end table | |
7796 | ||
4eb4cf57 | 7797 | @node History |
ed447b95 RP |
7798 | @section Command history |
7799 | ||
7800 | @value{GDBN} can keep track of the commands you type during your | |
7801 | debugging sessions, so that you can be certain of precisely what | |
7802 | happened. Use these commands to manage the @value{GDBN} command | |
7803 | history facility. | |
1041a570 | 7804 | |
70b88761 RP |
7805 | @table @code |
7806 | @cindex history substitution | |
7807 | @cindex history file | |
7808 | @kindex set history filename | |
9a27b06e | 7809 | @kindex GDBHISTFILE |
70b88761 | 7810 | @item set history filename @var{fname} |
9a27b06e RP |
7811 | Set the name of the @value{GDBN} command history file to @var{fname}. |
7812 | This is the file where @value{GDBN} reads an initial command history | |
7813 | list, and where it writes the command history from this session when it | |
7814 | exits. You can access this list through history expansion or through | |
7815 | the history command editing characters listed below. This file defaults | |
7816 | to the value of the environment variable @code{GDBHISTFILE}, or to | |
70b88761 RP |
7817 | @file{./.gdb_history} if this variable is not set. |
7818 | ||
7819 | @cindex history save | |
7820 | @kindex set history save | |
7821 | @item set history save | |
7822 | @itemx set history save on | |
7823 | Record command history in a file, whose name may be specified with the | |
7824 | @code{set history filename} command. By default, this option is disabled. | |
7825 | ||
7826 | @item set history save off | |
7827 | Stop recording command history in a file. | |
7828 | ||
7829 | @cindex history size | |
7830 | @kindex set history size | |
7831 | @item set history size @var{size} | |
9a27b06e | 7832 | Set the number of commands which @value{GDBN} keeps in its history list. |
70b88761 RP |
7833 | This defaults to the value of the environment variable |
7834 | @code{HISTSIZE}, or to 256 if this variable is not set. | |
7835 | @end table | |
7836 | ||
7837 | @cindex history expansion | |
7838 | History expansion assigns special meaning to the character @kbd{!}. | |
ed447b95 | 7839 | @ifset have-readline-appendices |
1041a570 | 7840 | @xref{Event Designators}. |
ed447b95 RP |
7841 | @end ifset |
7842 | ||
70b88761 RP |
7843 | Since @kbd{!} is also the logical not operator in C, history expansion |
7844 | is off by default. If you decide to enable history expansion with the | |
7845 | @code{set history expansion on} command, you may sometimes need to | |
7846 | follow @kbd{!} (when it is used as logical not, in an expression) with | |
7847 | a space or a tab to prevent it from being expanded. The readline | |
9a27b06e | 7848 | history facilities do not attempt substitution on the strings |
70b88761 RP |
7849 | @kbd{!=} and @kbd{!(}, even when history expansion is enabled. |
7850 | ||
7851 | The commands to control history expansion are: | |
7852 | ||
7853 | @table @code | |
70b88761 RP |
7854 | @kindex set history expansion |
7855 | @item set history expansion on | |
7856 | @itemx set history expansion | |
7857 | Enable history expansion. History expansion is off by default. | |
7858 | ||
7859 | @item set history expansion off | |
7860 | Disable history expansion. | |
7861 | ||
7862 | The readline code comes with more complete documentation of | |
af215b1a | 7863 | editing and history expansion features. Users unfamiliar with @sc{gnu} Emacs |
e251e767 | 7864 | or @code{vi} may wish to read it. |
ed447b95 | 7865 | @ifset have-readline-appendices |
70b88761 | 7866 | @xref{Command Line Editing}. |
ed447b95 | 7867 | @end ifset |
70b88761 RP |
7868 | |
7869 | @c @group | |
7870 | @kindex show history | |
7871 | @item show history | |
7872 | @itemx show history filename | |
7873 | @itemx show history save | |
7874 | @itemx show history size | |
7875 | @itemx show history expansion | |
18fae2a8 | 7876 | These commands display the state of the @value{GDBN} history parameters. |
70b88761 RP |
7877 | @code{show history} by itself displays all four states. |
7878 | @c @end group | |
70b88761 RP |
7879 | @end table |
7880 | ||
7881 | @table @code | |
7882 | @kindex show commands | |
7883 | @item show commands | |
7884 | Display the last ten commands in the command history. | |
7885 | ||
7886 | @item show commands @var{n} | |
7887 | Print ten commands centered on command number @var{n}. | |
7888 | ||
7889 | @item show commands + | |
7890 | Print ten commands just after the commands last printed. | |
70b88761 RP |
7891 | @end table |
7892 | ||
4eb4cf57 | 7893 | @node Screen Size |
93928b60 | 7894 | @section Screen size |
70b88761 RP |
7895 | @cindex size of screen |
7896 | @cindex pauses in output | |
1041a570 | 7897 | |
a1eff6c2 RP |
7898 | Certain commands to @value{GDBN} may produce large amounts of |
7899 | information output to the screen. To help you read all of it, | |
7900 | @value{GDBN} pauses and asks you for input at the end of each page of | |
7901 | output. Type @key{RET} when you want to continue the output, or @kbd{q} | |
34ae25cd RP |
7902 | to discard the remaining output. Also, the screen width setting |
7903 | determines when to wrap lines of output. Depending on what is being | |
7904 | printed, @value{GDBN} tries to break the line at a readable place, | |
70b88761 RP |
7905 | rather than simply letting it overflow onto the following line. |
7906 | ||
18fae2a8 | 7907 | Normally @value{GDBN} knows the size of the screen from the termcap data base |
70b88761 RP |
7908 | together with the value of the @code{TERM} environment variable and the |
7909 | @code{stty rows} and @code{stty cols} settings. If this is not correct, | |
7910 | you can override it with the @code{set height} and @code{set | |
7911 | width} commands: | |
7912 | ||
7913 | @table @code | |
70b88761 RP |
7914 | @kindex set height |
7915 | @kindex set width | |
7916 | @kindex show width | |
7917 | @kindex show height | |
af215b1a VM |
7918 | @item set height @var{lpp} |
7919 | @itemx show height | |
7920 | @itemx set width @var{cpl} | |
7921 | @itemx show width | |
70b88761 RP |
7922 | These @code{set} commands specify a screen height of @var{lpp} lines and |
7923 | a screen width of @var{cpl} characters. The associated @code{show} | |
7924 | commands display the current settings. | |
7925 | ||
af215b1a VM |
7926 | If you specify a height of zero lines, @value{GDBN} does not pause during |
7927 | output no matter how long the output is. This is useful if output is to a | |
7928 | file or to an editor buffer. | |
d55320a0 RP |
7929 | |
7930 | Likewise, you can specify @samp{set width 0} to prevent @value{GDBN} | |
7931 | from wrapping its output. | |
70b88761 RP |
7932 | @end table |
7933 | ||
4eb4cf57 | 7934 | @node Numbers |
70b88761 RP |
7935 | @section Numbers |
7936 | @cindex number representation | |
7937 | @cindex entering numbers | |
1041a570 | 7938 | |
18fae2a8 | 7939 | You can always enter numbers in octal, decimal, or hexadecimal in @value{GDBN} by |
70b88761 RP |
7940 | the usual conventions: octal numbers begin with @samp{0}, decimal |
7941 | numbers end with @samp{.}, and hexadecimal numbers begin with @samp{0x}. | |
7942 | Numbers that begin with none of these are, by default, entered in base | |
7943 | 10; likewise, the default display for numbers---when no particular | |
7944 | format is specified---is base 10. You can change the default base for | |
7945 | both input and output with the @code{set radix} command. | |
7946 | ||
7947 | @table @code | |
af215b1a VM |
7948 | @kindex set input-radix |
7949 | @item set input-radix @var{base} | |
7950 | Set the default base for numeric input. Supported choices | |
d55320a0 | 7951 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be |
70b88761 RP |
7952 | specified either unambiguously or using the current default radix; for |
7953 | example, any of | |
7954 | ||
af215b1a | 7955 | @smallexample |
70b88761 RP |
7956 | set radix 012 |
7957 | set radix 10. | |
7958 | set radix 0xa | |
af215b1a | 7959 | @end smallexample |
70b88761 RP |
7960 | |
7961 | @noindent | |
9a27b06e RP |
7962 | sets the base to decimal. On the other hand, @samp{set radix 10} |
7963 | leaves the radix unchanged no matter what it was. | |
70b88761 | 7964 | |
af215b1a VM |
7965 | @kindex set output-radix |
7966 | @item set output-radix @var{base} | |
7967 | Set the default base for numeric display. Supported choices | |
7968 | for @var{base} are decimal 8, 10, or 16. @var{base} must itself be | |
7969 | specified either unambiguously or using the current default radix. | |
7970 | ||
7971 | @kindex show input-radix | |
7972 | @item show input-radix | |
7973 | Display the current default base for numeric input. | |
7974 | ||
7975 | @kindex show output-radix | |
7976 | @item show output-radix | |
7977 | Display the current default base for numeric display. | |
70b88761 RP |
7978 | @end table |
7979 | ||
4eb4cf57 | 7980 | @node Messages/Warnings |
93928b60 | 7981 | @section Optional warnings and messages |
1041a570 | 7982 | |
18fae2a8 | 7983 | By default, @value{GDBN} is silent about its inner workings. If you are running |
70b88761 | 7984 | on a slow machine, you may want to use the @code{set verbose} command. |
af215b1a | 7985 | This makes @value{GDBN} tell you when it does a lengthy internal operation, so |
1041a570 | 7986 | you will not think it has crashed. |
70b88761 | 7987 | |
1041a570 | 7988 | Currently, the messages controlled by @code{set verbose} are those |
d48da190 | 7989 | which announce that the symbol table for a source file is being read; |
93928b60 | 7990 | see @code{symbol-file} in @ref{Files, ,Commands to specify files}. |
70b88761 RP |
7991 | |
7992 | @table @code | |
7993 | @kindex set verbose | |
7994 | @item set verbose on | |
93918348 | 7995 | Enables @value{GDBN} output of certain informational messages. |
70b88761 RP |
7996 | |
7997 | @item set verbose off | |
93918348 | 7998 | Disables @value{GDBN} output of certain informational messages. |
70b88761 RP |
7999 | |
8000 | @kindex show verbose | |
8001 | @item show verbose | |
8002 | Displays whether @code{set verbose} is on or off. | |
8003 | @end table | |
8004 | ||
18fae2a8 | 8005 | By default, if @value{GDBN} encounters bugs in the symbol table of an object |
b80282d5 | 8006 | file, it is silent; but if you are debugging a compiler, you may find |
93928b60 | 8007 | this information useful (@pxref{Symbol Errors, ,Errors reading symbol files}). |
70b88761 RP |
8008 | |
8009 | @table @code | |
8010 | @kindex set complaints | |
8011 | @item set complaints @var{limit} | |
18fae2a8 | 8012 | Permits @value{GDBN} to output @var{limit} complaints about each type of unusual |
70b88761 RP |
8013 | symbols before becoming silent about the problem. Set @var{limit} to |
8014 | zero to suppress all complaints; set it to a large number to prevent | |
8015 | complaints from being suppressed. | |
8016 | ||
8017 | @kindex show complaints | |
8018 | @item show complaints | |
18fae2a8 | 8019 | Displays how many symbol complaints @value{GDBN} is permitted to produce. |
70b88761 RP |
8020 | @end table |
8021 | ||
18fae2a8 | 8022 | By default, @value{GDBN} is cautious, and asks what sometimes seems to be a |
70b88761 RP |
8023 | lot of stupid questions to confirm certain commands. For example, if |
8024 | you try to run a program which is already running: | |
1041a570 | 8025 | |
70b88761 | 8026 | @example |
18fae2a8 | 8027 | (@value{GDBP}) run |
70b88761 | 8028 | The program being debugged has been started already. |
e251e767 | 8029 | Start it from the beginning? (y or n) |
70b88761 RP |
8030 | @end example |
8031 | ||
29a2b744 | 8032 | If you are willing to unflinchingly face the consequences of your own |
70b88761 RP |
8033 | commands, you can disable this ``feature'': |
8034 | ||
8035 | @table @code | |
8036 | @kindex set confirm | |
8037 | @cindex flinching | |
8038 | @cindex confirmation | |
8039 | @cindex stupid questions | |
8040 | @item set confirm off | |
8041 | Disables confirmation requests. | |
8042 | ||
8043 | @item set confirm on | |
8044 | Enables confirmation requests (the default). | |
8045 | ||
70b88761 | 8046 | @kindex show confirm |
af215b1a | 8047 | @item show confirm |
70b88761 RP |
8048 | Displays state of confirmation requests. |
8049 | @end table | |
8050 | ||
4eb4cf57 | 8051 | @node Sequences |
70b88761 RP |
8052 | @chapter Canned Sequences of Commands |
8053 | ||
29a2b744 | 8054 | Aside from breakpoint commands (@pxref{Break Commands, ,Breakpoint |
93928b60 | 8055 | command lists}), @value{GDBN} provides two ways to store sequences of commands |
1041a570 | 8056 | for execution as a unit: user-defined commands and command files. |
70b88761 RP |
8057 | |
8058 | @menu | |
ed447b95 RP |
8059 | * Define:: User-defined commands |
8060 | * Hooks:: User-defined command hooks | |
8061 | * Command Files:: Command files | |
8062 | * Output:: Commands for controlled output | |
70b88761 RP |
8063 | @end menu |
8064 | ||
4eb4cf57 | 8065 | @node Define |
ed447b95 | 8066 | @section User-defined commands |
70b88761 RP |
8067 | |
8068 | @cindex user-defined command | |
af215b1a VM |
8069 | A @dfn{user-defined command} is a sequence of @value{GDBN} commands to which |
8070 | you assign a new name as a command. This is done with the @code{define} | |
8071 | command. User commands may accept up to 10 arguments separated by whitespace. | |
8072 | Arguments are accessed within the user command via @var{$arg0@dots{}$arg9}. | |
8073 | A trivial example: | |
8074 | ||
8075 | @smallexample | |
8076 | define adder | |
8077 | print $arg0 + $arg1 + $arg2 | |
8078 | @end smallexample | |
8079 | ||
8080 | @noindent To execute the command use: | |
8081 | ||
8082 | @smallexample | |
8083 | adder 1 2 3 | |
8084 | @end smallexample | |
8085 | ||
8086 | @noindent This defines the command @code{adder}, which prints the sum of | |
8087 | its three arguments. Note the arguments are text substitutions, so they may | |
8088 | reference variables, use complex expressions, or even perform inferior | |
8089 | functions calls. | |
70b88761 RP |
8090 | |
8091 | @table @code | |
70b88761 | 8092 | @kindex define |
af215b1a | 8093 | @item define @var{commandname} |
70b88761 RP |
8094 | Define a command named @var{commandname}. If there is already a command |
8095 | by that name, you are asked to confirm that you want to redefine it. | |
8096 | ||
18fae2a8 | 8097 | The definition of the command is made up of other @value{GDBN} command lines, |
70b88761 RP |
8098 | which are given following the @code{define} command. The end of these |
8099 | commands is marked by a line containing @code{end}. | |
8100 | ||
d0b2a91c PB |
8101 | @kindex if |
8102 | @kindex else | |
af215b1a | 8103 | @item if |
d0b2a91c PB |
8104 | Takes a single argument, which is an expression to evaluate. |
8105 | It is followed by a series of commands that are executed | |
8106 | only if the expression is true (nonzero). | |
8107 | There can then optionally be a line @code{else}, followed | |
8108 | by a series of commands that are only executed if the expression | |
8109 | was false. The end of the list is marked by a line containing @code{end}. | |
8110 | ||
d0b2a91c | 8111 | @kindex while |
af215b1a VM |
8112 | @item while |
8113 | The syntax is similar to @code{if}: the command takes a single argument, | |
d0b2a91c PB |
8114 | which is an expression to evaluate, and must be followed by the commands to |
8115 | execute, one per line, terminated by an @code{end}. | |
8116 | The commands are executed repeatedly as long as the expression | |
8117 | evaluates to true. | |
8118 | ||
70b88761 | 8119 | @kindex document |
af215b1a VM |
8120 | @item document @var{commandname} |
8121 | Document the user-defined command @var{commandname}, so that it can be | |
8122 | accessed by @code{help}. The command @var{commandname} must already be | |
8123 | defined. This command reads lines of documentation just as @code{define} | |
8124 | reads the lines of the command definition, ending with @code{end}. | |
8125 | After the @code{document} command is finished, @code{help} on command | |
8126 | @var{commandname} displays the documentation you have written. | |
70b88761 RP |
8127 | |
8128 | You may use the @code{document} command again to change the | |
8129 | documentation of a command. Redefining the command with @code{define} | |
8130 | does not change the documentation. | |
8131 | ||
70b88761 | 8132 | @kindex help user-defined |
af215b1a | 8133 | @item help user-defined |
70b88761 RP |
8134 | List all user-defined commands, with the first line of the documentation |
8135 | (if any) for each. | |
8136 | ||
af215b1a | 8137 | @kindex show user |
4768ba62 JG |
8138 | @item show user |
8139 | @itemx show user @var{commandname} | |
18fae2a8 | 8140 | Display the @value{GDBN} commands used to define @var{commandname} (but not its |
70b88761 RP |
8141 | documentation). If no @var{commandname} is given, display the |
8142 | definitions for all user-defined commands. | |
8143 | @end table | |
8144 | ||
d0b2a91c | 8145 | When user-defined commands are executed, the |
70b88761 RP |
8146 | commands of the definition are not printed. An error in any command |
8147 | stops execution of the user-defined command. | |
8148 | ||
af215b1a VM |
8149 | If used interactively, commands that would ask for confirmation proceed |
8150 | without asking when used inside a user-defined command. Many @value{GDBN} | |
8151 | commands that normally print messages to say what they are doing omit the | |
8152 | messages when used in a user-defined command. | |
70b88761 | 8153 | |
35a15d60 | 8154 | @node Hooks |
93928b60 | 8155 | @section User-defined command hooks |
35a15d60 JG |
8156 | @cindex command files |
8157 | ||
8158 | You may define @emph{hooks}, which are a special kind of user-defined | |
8159 | command. Whenever you run the command @samp{foo}, if the user-defined | |
8160 | command @samp{hook-foo} exists, it is executed (with no arguments) | |
8161 | before that command. | |
8162 | ||
1d7c3357 RP |
8163 | In addition, a pseudo-command, @samp{stop} exists. Defining |
8164 | (@samp{hook-stop}) makes the associated commands execute every time | |
8165 | execution stops in your program: before breakpoint commands are run, | |
8166 | displays are printed, or the stack frame is printed. | |
35a15d60 | 8167 | |
1d7c3357 RP |
8168 | @ifclear BARETARGET |
8169 | For example, to ignore @code{SIGALRM} signals while | |
8170 | single-stepping, but treat them normally during normal execution, | |
8171 | you could define: | |
35a15d60 JG |
8172 | |
8173 | @example | |
8174 | define hook-stop | |
8175 | handle SIGALRM nopass | |
8176 | end | |
8177 | ||
8178 | define hook-run | |
8179 | handle SIGALRM pass | |
8180 | end | |
8181 | ||
8182 | define hook-continue | |
8183 | handle SIGLARM pass | |
8184 | end | |
8185 | @end example | |
1d7c3357 | 8186 | @end ifclear |
35a15d60 | 8187 | |
1d7c3357 RP |
8188 | You can define a hook for any single-word command in @value{GDBN}, but |
8189 | not for command aliases; you should define a hook for the basic command | |
8190 | name, e.g. @code{backtrace} rather than @code{bt}. | |
8191 | @c FIXME! So how does Joe User discover whether a command is an alias | |
8192 | @c or not? | |
8193 | If an error occurs during the execution of your hook, execution of | |
8194 | @value{GDBN} commands stops and @value{GDBN} issues a prompt | |
8195 | (before the command that you actually typed had a chance to run). | |
35a15d60 | 8196 | |
93918348 | 8197 | If you try to define a hook which does not match any known command, you |
9a27b06e | 8198 | get a warning from the @code{define} command. |
35a15d60 | 8199 | |
4eb4cf57 | 8200 | @node Command Files |
93928b60 | 8201 | @section Command files |
70b88761 RP |
8202 | |
8203 | @cindex command files | |
af215b1a VM |
8204 | A command file for @value{GDBN} is a file of lines that are @value{GDBN} |
8205 | commands. Comments (lines starting with @kbd{#}) may also be included. | |
8206 | An empty line in a command file does nothing; it does not mean to repeat | |
8207 | the last command, as it would from the terminal. | |
70b88761 RP |
8208 | |
8209 | @cindex init file | |
18fae2a8 RP |
8210 | @cindex @file{@value{GDBINIT}} |
8211 | When you start @value{GDBN}, it automatically executes commands from its | |
64a01450 JK |
8212 | @dfn{init files}. These are files named @file{@value{GDBINIT}}. |
8213 | @value{GDBN} reads the init file (if any) in your home directory, then | |
8214 | processes command line options and operands, and then reads the init | |
8215 | file (if any) in the current working directory. This is so the init | |
8216 | file in your home directory can set options (such as @code{set | |
8d43be62 | 8217 | complaints}) which affect the processing of the command line options and |
64a01450 JK |
8218 | operands. The init files are not executed if you use the @samp{-nx} |
8219 | option; @pxref{Mode Options, ,Choosing modes}. | |
51b65b74 RP |
8220 | |
8221 | @ifset GENERIC | |
8222 | @cindex init file name | |
8223 | On some configurations of @value{GDBN}, the init file is known by a | |
8224 | different name (these are typically environments where a specialized | |
af215b1a VM |
8225 | form of @value{GDBN} may need to coexist with other forms, |
8226 | hence a different name | |
51b65b74 RP |
8227 | for the specialized version's init file). These are the environments |
8228 | with special init file names: | |
8229 | ||
51b65b74 | 8230 | @kindex .vxgdbinit |
af215b1a | 8231 | @itemize @bullet |
51b65b74 RP |
8232 | @item |
8233 | VxWorks (Wind River Systems real-time OS): @samp{.vxgdbinit} | |
8234 | ||
8235 | @kindex .os68gdbinit | |
8236 | @item | |
8237 | OS68K (Enea Data Systems real-time OS): @samp{.os68gdbinit} | |
8238 | ||
8239 | @kindex .esgdbinit | |
8240 | @item | |
8241 | ES-1800 (Ericsson Telecom AB M68000 emulator): @samp{.esgdbinit} | |
8242 | @end itemize | |
8243 | @end ifset | |
8244 | ||
8245 | You can also request the execution of a command file with the | |
8246 | @code{source} command: | |
70b88761 RP |
8247 | |
8248 | @table @code | |
70b88761 | 8249 | @kindex source |
af215b1a | 8250 | @item source @var{filename} |
70b88761 RP |
8251 | Execute the command file @var{filename}. |
8252 | @end table | |
8253 | ||
8254 | The lines in a command file are executed sequentially. They are not | |
8255 | printed as they are executed. An error in any command terminates execution | |
8256 | of the command file. | |
8257 | ||
8258 | Commands that would ask for confirmation if used interactively proceed | |
18fae2a8 | 8259 | without asking when used in a command file. Many @value{GDBN} commands that |
70b88761 RP |
8260 | normally print messages to say what they are doing omit the messages |
8261 | when called from command files. | |
8262 | ||
4eb4cf57 | 8263 | @node Output |
93928b60 | 8264 | @section Commands for controlled output |
70b88761 RP |
8265 | |
8266 | During the execution of a command file or a user-defined command, normal | |
18fae2a8 | 8267 | @value{GDBN} output is suppressed; the only output that appears is what is |
70b88761 RP |
8268 | explicitly printed by the commands in the definition. This section |
8269 | describes three commands useful for generating exactly the output you | |
8270 | want. | |
8271 | ||
8272 | @table @code | |
70b88761 | 8273 | @kindex echo |
af215b1a | 8274 | @item echo @var{text} |
29a2b744 RP |
8275 | @c I do not consider backslash-space a standard C escape sequence |
8276 | @c because it is not in ANSI. | |
1041a570 RP |
8277 | Print @var{text}. Nonprinting characters can be included in |
8278 | @var{text} using C escape sequences, such as @samp{\n} to print a | |
9a27b06e | 8279 | newline. @strong{No newline is printed unless you specify one.} |
1041a570 | 8280 | In addition to the standard C escape sequences, a backslash followed |
ed447b95 | 8281 | by a space stands for a space. This is useful for displaying a |
1041a570 RP |
8282 | string with spaces at the beginning or the end, since leading and |
8283 | trailing spaces are otherwise trimmed from all arguments. | |
8284 | To print @samp{@w{ }and foo =@w{ }}, use the command | |
8285 | @samp{echo \@w{ }and foo = \@w{ }}. | |
70b88761 RP |
8286 | |
8287 | A backslash at the end of @var{text} can be used, as in C, to continue | |
8288 | the command onto subsequent lines. For example, | |
8289 | ||
8290 | @example | |
8291 | echo This is some text\n\ | |
8292 | which is continued\n\ | |
8293 | onto several lines.\n | |
8294 | @end example | |
8295 | ||
8296 | produces the same output as | |
8297 | ||
8298 | @example | |
8299 | echo This is some text\n | |
8300 | echo which is continued\n | |
8301 | echo onto several lines.\n | |
8302 | @end example | |
8303 | ||
70b88761 | 8304 | @kindex output |
af215b1a | 8305 | @item output @var{expression} |
70b88761 RP |
8306 | Print the value of @var{expression} and nothing but that value: no |
8307 | newlines, no @samp{$@var{nn} = }. The value is not entered in the | |
af215b1a VM |
8308 | value history either. @xref{Expressions, ,Expressions}, for more information |
8309 | on expressions. | |
70b88761 RP |
8310 | |
8311 | @item output/@var{fmt} @var{expression} | |
8312 | Print the value of @var{expression} in format @var{fmt}. You can use | |
ed447b95 RP |
8313 | the same formats as for @code{print}. @xref{Output Formats,,Output |
8314 | formats}, for more information. | |
70b88761 | 8315 | |
70b88761 | 8316 | @kindex printf |
af215b1a | 8317 | @item printf @var{string}, @var{expressions}@dots{} |
70b88761 | 8318 | Print the values of the @var{expressions} under the control of |
d55320a0 RP |
8319 | @var{string}. The @var{expressions} are separated by commas and may be |
8320 | either numbers or pointers. Their values are printed as specified by | |
8321 | @var{string}, exactly as if your program were to execute the C | |
8322 | subroutine | |
70b88761 RP |
8323 | |
8324 | @example | |
8325 | printf (@var{string}, @var{expressions}@dots{}); | |
8326 | @end example | |
8327 | ||
8328 | For example, you can print two values in hex like this: | |
8329 | ||
0fd24984 | 8330 | @smallexample |
70b88761 | 8331 | printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo |
0fd24984 | 8332 | @end smallexample |
70b88761 RP |
8333 | |
8334 | The only backslash-escape sequences that you can use in the format | |
8335 | string are the simple ones that consist of backslash followed by a | |
8336 | letter. | |
8337 | @end table | |
8338 | ||
18fae2a8 | 8339 | @ifclear DOSHOST |
4eb4cf57 | 8340 | @node Emacs |
af215b1a | 8341 | @chapter Using @value{GDBN} under @sc{gnu} Emacs |
70b88761 | 8342 | |
af215b1a VM |
8343 | @cindex Emacs |
8344 | @cindex @sc{gnu} Emacs | |
8345 | A special interface allows you to use @sc{gnu} Emacs to view (and | |
70b88761 | 8346 | edit) the source files for the program you are debugging with |
18fae2a8 | 8347 | @value{GDBN}. |
70b88761 RP |
8348 | |
8349 | To use this interface, use the command @kbd{M-x gdb} in Emacs. Give the | |
8350 | executable file you want to debug as an argument. This command starts | |
18fae2a8 | 8351 | @value{GDBN} as a subprocess of Emacs, with input and output through a newly |
70b88761 RP |
8352 | created Emacs buffer. |
8353 | ||
18fae2a8 | 8354 | Using @value{GDBN} under Emacs is just like using @value{GDBN} normally except for two |
70b88761 RP |
8355 | things: |
8356 | ||
8357 | @itemize @bullet | |
8358 | @item | |
e251e767 | 8359 | All ``terminal'' input and output goes through the Emacs buffer. |
70b88761 RP |
8360 | @end itemize |
8361 | ||
18fae2a8 | 8362 | This applies both to @value{GDBN} commands and their output, and to the input |
70b88761 RP |
8363 | and output done by the program you are debugging. |
8364 | ||
8365 | This is useful because it means that you can copy the text of previous | |
8366 | commands and input them again; you can even use parts of the output | |
8367 | in this way. | |
8368 | ||
3d3ab540 RP |
8369 | All the facilities of Emacs' Shell mode are available for interacting |
8370 | with your program. In particular, you can send signals the usual | |
8371 | way---for example, @kbd{C-c C-c} for an interrupt, @kbd{C-c C-z} for a | |
8372 | stop. | |
70b88761 RP |
8373 | |
8374 | @itemize @bullet | |
8375 | @item | |
18fae2a8 | 8376 | @value{GDBN} displays source code through Emacs. |
70b88761 RP |
8377 | @end itemize |
8378 | ||
18fae2a8 RP |
8379 | Each time @value{GDBN} displays a stack frame, Emacs automatically finds the |
8380 | source file for that frame and puts an arrow (@samp{=>}) at the | |
70b88761 | 8381 | left margin of the current line. Emacs uses a separate buffer for |
fe715d06 | 8382 | source display, and splits the screen to show both your @value{GDBN} session |
70b88761 RP |
8383 | and the source. |
8384 | ||
18fae2a8 | 8385 | Explicit @value{GDBN} @code{list} or search commands still produce output as |
9a27b06e | 8386 | usual, but you probably have no reason to use them from Emacs. |
70b88761 RP |
8387 | |
8388 | @quotation | |
8389 | @emph{Warning:} If the directory where your program resides is not your | |
8390 | current directory, it can be easy to confuse Emacs about the location of | |
9a27b06e | 8391 | the source files, in which case the auxiliary display buffer does not |
18fae2a8 RP |
8392 | appear to show your source. @value{GDBN} can find programs by searching your |
8393 | environment's @code{PATH} variable, so the @value{GDBN} input and output | |
9a27b06e | 8394 | session proceeds normally; but Emacs does not get enough information |
18fae2a8 RP |
8395 | back from @value{GDBN} to locate the source files in this situation. To |
8396 | avoid this problem, either start @value{GDBN} mode from the directory where | |
b550c03a | 8397 | your program resides, or specify an absolute file name when prompted for the |
70b88761 RP |
8398 | @kbd{M-x gdb} argument. |
8399 | ||
18fae2a8 | 8400 | A similar confusion can result if you use the @value{GDBN} @code{file} command to |
70b88761 | 8401 | switch to debugging a program in some other location, from an existing |
18fae2a8 | 8402 | @value{GDBN} buffer in Emacs. |
70b88761 RP |
8403 | @end quotation |
8404 | ||
8405 | By default, @kbd{M-x gdb} calls the program called @file{gdb}. If | |
18fae2a8 | 8406 | you need to call @value{GDBN} by a different name (for example, if you keep |
70b88761 RP |
8407 | several configurations around, with different names) you can set the |
8408 | Emacs variable @code{gdb-command-name}; for example, | |
1041a570 | 8409 | |
70b88761 RP |
8410 | @example |
8411 | (setq gdb-command-name "mygdb") | |
8412 | @end example | |
1041a570 | 8413 | |
70b88761 RP |
8414 | @noindent |
8415 | (preceded by @kbd{ESC ESC}, or typed in the @code{*scratch*} buffer, or | |
9a27b06e | 8416 | in your @file{.emacs} file) makes Emacs call the program named |
70b88761 RP |
8417 | ``@code{mygdb}'' instead. |
8418 | ||
18fae2a8 | 8419 | In the @value{GDBN} I/O buffer, you can use these special Emacs commands in |
70b88761 RP |
8420 | addition to the standard Shell mode commands: |
8421 | ||
8422 | @table @kbd | |
8423 | @item C-h m | |
18fae2a8 | 8424 | Describe the features of Emacs' @value{GDBN} Mode. |
70b88761 RP |
8425 | |
8426 | @item M-s | |
18fae2a8 | 8427 | Execute to another source line, like the @value{GDBN} @code{step} command; also |
70b88761 RP |
8428 | update the display window to show the current file and location. |
8429 | ||
8430 | @item M-n | |
8431 | Execute to next source line in this function, skipping all function | |
18fae2a8 | 8432 | calls, like the @value{GDBN} @code{next} command. Then update the display window |
70b88761 RP |
8433 | to show the current file and location. |
8434 | ||
8435 | @item M-i | |
18fae2a8 | 8436 | Execute one instruction, like the @value{GDBN} @code{stepi} command; update |
70b88761 RP |
8437 | display window accordingly. |
8438 | ||
8439 | @item M-x gdb-nexti | |
18fae2a8 | 8440 | Execute to next instruction, using the @value{GDBN} @code{nexti} command; update |
70b88761 RP |
8441 | display window accordingly. |
8442 | ||
8443 | @item C-c C-f | |
18fae2a8 | 8444 | Execute until exit from the selected stack frame, like the @value{GDBN} |
70b88761 RP |
8445 | @code{finish} command. |
8446 | ||
8447 | @item M-c | |
18fae2a8 | 8448 | Continue execution of your program, like the @value{GDBN} @code{continue} |
1041a570 | 8449 | command. |
203eea5d RP |
8450 | |
8451 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-p}. | |
70b88761 RP |
8452 | |
8453 | @item M-u | |
8454 | Go up the number of frames indicated by the numeric argument | |
af215b1a | 8455 | (@pxref{Arguments, , Numeric Arguments, Emacs, The @sc{gnu} Emacs Manual}), |
18fae2a8 | 8456 | like the @value{GDBN} @code{up} command. |
203eea5d | 8457 | |
1041a570 | 8458 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-u}. |
70b88761 RP |
8459 | |
8460 | @item M-d | |
8461 | Go down the number of frames indicated by the numeric argument, like the | |
18fae2a8 | 8462 | @value{GDBN} @code{down} command. |
203eea5d RP |
8463 | |
8464 | @emph{Warning:} In Emacs v19, this command is @kbd{C-c C-d}. | |
70b88761 RP |
8465 | |
8466 | @item C-x & | |
8467 | Read the number where the cursor is positioned, and insert it at the end | |
18fae2a8 | 8468 | of the @value{GDBN} I/O buffer. For example, if you wish to disassemble code |
70b88761 RP |
8469 | around an address that was displayed earlier, type @kbd{disassemble}; |
8470 | then move the cursor to the address display, and pick up the | |
e251e767 | 8471 | argument for @code{disassemble} by typing @kbd{C-x &}. |
70b88761 | 8472 | |
ed447b95 | 8473 | You can customize this further by defining elements of the list |
70b88761 RP |
8474 | @code{gdb-print-command}; once it is defined, you can format or |
8475 | otherwise process numbers picked up by @kbd{C-x &} before they are | |
9a27b06e RP |
8476 | inserted. A numeric argument to @kbd{C-x &} indicates that you |
8477 | wish special formatting, and also acts as an index to pick an element of the | |
70b88761 RP |
8478 | list. If the list element is a string, the number to be inserted is |
8479 | formatted using the Emacs function @code{format}; otherwise the number | |
8480 | is passed as an argument to the corresponding list element. | |
70b88761 RP |
8481 | @end table |
8482 | ||
8483 | In any source file, the Emacs command @kbd{C-x SPC} (@code{gdb-break}) | |
18fae2a8 | 8484 | tells @value{GDBN} to set a breakpoint on the source line point is on. |
70b88761 RP |
8485 | |
8486 | If you accidentally delete the source-display buffer, an easy way to get | |
18fae2a8 | 8487 | it back is to type the command @code{f} in the @value{GDBN} buffer, to |
9a27b06e | 8488 | request a frame display; when you run under Emacs, this recreates |
70b88761 RP |
8489 | the source buffer if necessary to show you the context of the current |
8490 | frame. | |
8491 | ||
8492 | The source files displayed in Emacs are in ordinary Emacs buffers | |
8493 | which are visiting the source files in the usual way. You can edit | |
18fae2a8 | 8494 | the files with these buffers if you wish; but keep in mind that @value{GDBN} |
70b88761 | 8495 | communicates with Emacs in terms of line numbers. If you add or |
9a27b06e | 8496 | delete lines from the text, the line numbers that @value{GDBN} knows cease |
ed447b95 | 8497 | to correspond properly with the code. |
70b88761 RP |
8498 | |
8499 | @c The following dropped because Epoch is nonstandard. Reactivate | |
e0d3ace2 | 8500 | @c if/when v19 does something similar. ---doc@cygnus.com 19dec1990 |
70b88761 | 8501 | @ignore |
af215b1a VM |
8502 | @kindex Emacs Epoch environment |
8503 | @kindex Epoch | |
70b88761 RP |
8504 | @kindex inspect |
8505 | ||
af215b1a VM |
8506 | Version 18 of @sc{gnu} Emacs has a built-in window system |
8507 | called the @code{epoch} | |
70b88761 RP |
8508 | environment. Users of this environment can use a new command, |
8509 | @code{inspect} which performs identically to @code{print} except that | |
8510 | each value is printed in its own window. | |
8511 | @end ignore | |
18fae2a8 | 8512 | @end ifclear |
70b88761 | 8513 | |
18fae2a8 | 8514 | @ifset LUCID |
4eb4cf57 | 8515 | @node Energize |
18fae2a8 | 8516 | @chapter Using @value{GDBN} with Energize |
6ca72cc6 RP |
8517 | |
8518 | @cindex Energize | |
8519 | The Energize Programming System is an integrated development environment | |
8520 | that includes a point-and-click interface to many programming tools. | |
18fae2a8 RP |
8521 | When you use @value{GDBN} in this environment, you can use the standard |
8522 | Energize graphical interface to drive @value{GDBN}; you can also, if you | |
8523 | choose, type @value{GDBN} commands as usual in a debugging window. Even if | |
6ca72cc6 | 8524 | you use the graphical interface, the debugging window (which uses Emacs, |
af215b1a VM |
8525 | and resembles the standard @sc{gnu} Emacs interface to |
8526 | @value{GDBN}) displays the | |
6ca72cc6 RP |
8527 | equivalent commands, so that the history of your debugging session is |
8528 | properly reflected. | |
8529 | ||
18fae2a8 | 8530 | When Energize starts up a @value{GDBN} session, it uses one of the |
6ca72cc6 RP |
8531 | command-line options @samp{-energize} or @samp{-cadillac} (``cadillac'' |
8532 | is the name of the communications protocol used by the Energize system). | |
18fae2a8 | 8533 | This option makes @value{GDBN} run as one of the tools in the Energize Tool |
6ca72cc6 RP |
8534 | Set: it sends all output to the Energize kernel, and accept input from |
8535 | it as well. | |
8536 | ||
8537 | See the user manual for the Energize Programming System for | |
8538 | information on how to use the Energize graphical interface and the other | |
18fae2a8 | 8539 | development tools that Energize integrates with @value{GDBN}. |
6ca72cc6 | 8540 | |
18fae2a8 | 8541 | @end ifset |
4eb4cf57 | 8542 | |
18fae2a8 RP |
8543 | @node GDB Bugs |
8544 | @chapter Reporting Bugs in @value{GDBN} | |
ed447b95 RP |
8545 | @cindex bugs in @value{GDBN} |
8546 | @cindex reporting bugs in @value{GDBN} | |
70b88761 | 8547 | |
18fae2a8 | 8548 | Your bug reports play an essential role in making @value{GDBN} reliable. |
70b88761 RP |
8549 | |
8550 | Reporting a bug may help you by bringing a solution to your problem, or it | |
8551 | may not. But in any case the principal function of a bug report is to help | |
18fae2a8 RP |
8552 | the entire community by making the next version of @value{GDBN} work better. Bug |
8553 | reports are your contribution to the maintenance of @value{GDBN}. | |
70b88761 RP |
8554 | |
8555 | In order for a bug report to serve its purpose, you must include the | |
8556 | information that enables us to fix the bug. | |
8557 | ||
8558 | @menu | |
ed447b95 RP |
8559 | * Bug Criteria:: Have you found a bug? |
8560 | * Bug Reporting:: How to report bugs | |
70b88761 RP |
8561 | @end menu |
8562 | ||
4eb4cf57 | 8563 | @node Bug Criteria |
93928b60 | 8564 | @section Have you found a bug? |
ed447b95 | 8565 | @cindex bug criteria |
70b88761 RP |
8566 | |
8567 | If you are not sure whether you have found a bug, here are some guidelines: | |
8568 | ||
8569 | @itemize @bullet | |
0f153e74 | 8570 | @cindex fatal signal |
1d7c3357 RP |
8571 | @cindex debugger crash |
8572 | @cindex crash of debugger | |
af215b1a | 8573 | @item |
70b88761 | 8574 | If the debugger gets a fatal signal, for any input whatever, that is a |
18fae2a8 | 8575 | @value{GDBN} bug. Reliable debuggers never crash. |
70b88761 | 8576 | |
0f153e74 | 8577 | @cindex error on valid input |
af215b1a | 8578 | @item |
18fae2a8 | 8579 | If @value{GDBN} produces an error message for valid input, that is a bug. |
70b88761 | 8580 | |
ed447b95 | 8581 | @cindex invalid input |
af215b1a | 8582 | @item |
18fae2a8 | 8583 | If @value{GDBN} does not produce an error message for invalid input, |
70b88761 RP |
8584 | that is a bug. However, you should note that your idea of |
8585 | ``invalid input'' might be our idea of ``an extension'' or ``support | |
8586 | for traditional practice''. | |
8587 | ||
8588 | @item | |
8589 | If you are an experienced user of debugging tools, your suggestions | |
18fae2a8 | 8590 | for improvement of @value{GDBN} are welcome in any case. |
70b88761 RP |
8591 | @end itemize |
8592 | ||
4eb4cf57 | 8593 | @node Bug Reporting |
93928b60 | 8594 | @section How to report bugs |
0f153e74 | 8595 | @cindex bug reports |
18fae2a8 | 8596 | @cindex @value{GDBN} bugs, reporting |
70b88761 | 8597 | |
af215b1a | 8598 | A number of companies and individuals offer support for @sc{gnu} products. |
18fae2a8 | 8599 | If you obtained @value{GDBN} from a support organization, we recommend you |
e251e767 | 8600 | contact that organization first. |
70b88761 | 8601 | |
ed447b95 | 8602 | You can find contact information for many support companies and |
af215b1a | 8603 | individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs |
ed447b95 | 8604 | distribution. |
70b88761 | 8605 | |
18fae2a8 | 8606 | In any event, we also recommend that you send bug reports for @value{GDBN} to one |
70b88761 RP |
8607 | of these addresses: |
8608 | ||
8609 | @example | |
8610 | bug-gdb@@prep.ai.mit.edu | |
8611 | @{ucbvax|mit-eddie|uunet@}!prep.ai.mit.edu!bug-gdb | |
8612 | @end example | |
8613 | ||
8614 | @strong{Do not send bug reports to @samp{info-gdb}, or to | |
18fae2a8 | 8615 | @samp{help-gdb}, or to any newsgroups.} Most users of @value{GDBN} do not want to |
af215b1a | 8616 | receive bug reports. Those that do have arranged to receive @samp{bug-gdb}. |
70b88761 | 8617 | |
3d3ab540 RP |
8618 | The mailing list @samp{bug-gdb} has a newsgroup @samp{gnu.gdb.bug} which |
8619 | serves as a repeater. The mailing list and the newsgroup carry exactly | |
8620 | the same messages. Often people think of posting bug reports to the | |
8621 | newsgroup instead of mailing them. This appears to work, but it has one | |
8622 | problem which can be crucial: a newsgroup posting often lacks a mail | |
8623 | path back to the sender. Thus, if we need to ask for more information, | |
8624 | we may be unable to reach you. For this reason, it is better to send | |
8625 | bug reports to the mailing list. | |
70b88761 RP |
8626 | |
8627 | As a last resort, send bug reports on paper to: | |
8628 | ||
8629 | @example | |
af215b1a | 8630 | @sc{gnu} Debugger Bugs |
6c9638b4 FF |
8631 | Free Software Foundation Inc. |
8632 | 59 Temple Place - Suite 330 | |
8633 | Boston, MA 02111-1307 | |
8634 | USA | |
70b88761 RP |
8635 | @end example |
8636 | ||
8637 | The fundamental principle of reporting bugs usefully is this: | |
8638 | @strong{report all the facts}. If you are not sure whether to state a | |
8639 | fact or leave it out, state it! | |
8640 | ||
8641 | Often people omit facts because they think they know what causes the | |
29a2b744 | 8642 | problem and assume that some details do not matter. Thus, you might |
70b88761 | 8643 | assume that the name of the variable you use in an example does not matter. |
29a2b744 | 8644 | Well, probably it does not, but one cannot be sure. Perhaps the bug is a |
70b88761 RP |
8645 | stray memory reference which happens to fetch from the location where that |
8646 | name is stored in memory; perhaps, if the name were different, the contents | |
8647 | of that location would fool the debugger into doing the right thing despite | |
8648 | the bug. Play it safe and give a specific, complete example. That is the | |
8649 | easiest thing for you to do, and the most helpful. | |
8650 | ||
8651 | Keep in mind that the purpose of a bug report is to enable us to fix | |
af215b1a VM |
8652 | the bug if it is new to us. |
8653 | @c | |
8654 | @c FIX ME!!--What the heck does the following sentence mean, | |
8655 | @c in the context of the one above? | |
8656 | @c | |
8657 | @c It is not as important as what happens if the bug is already known. | |
8658 | @c | |
8659 | Therefore, always write your bug reports on | |
70b88761 RP |
8660 | the assumption that the bug has not been reported previously. |
8661 | ||
8662 | Sometimes people give a few sketchy facts and ask, ``Does this ring a | |
8663 | bell?'' Those bug reports are useless, and we urge everyone to | |
8664 | @emph{refuse to respond to them} except to chide the sender to report | |
8665 | bugs properly. | |
8666 | ||
8667 | To enable us to fix the bug, you should include all these things: | |
8668 | ||
8669 | @itemize @bullet | |
8670 | @item | |
18fae2a8 | 8671 | The version of @value{GDBN}. @value{GDBN} announces it if you start with no |
70b88761 RP |
8672 | arguments; you can also print it at any time using @code{show version}. |
8673 | ||
1041a570 | 8674 | Without this, we will not know whether there is any point in looking for |
18fae2a8 | 8675 | the bug in the current version of @value{GDBN}. |
70b88761 RP |
8676 | |
8677 | @item | |
ddf21240 JG |
8678 | The type of machine you are using, and the operating system name and |
8679 | version number. | |
70b88761 RP |
8680 | |
8681 | @item | |
18fae2a8 RP |
8682 | What compiler (and its version) was used to compile @value{GDBN}---e.g. |
8683 | ``@value{GCC}--2.0''. | |
70b88761 | 8684 | |
ddf21240 JG |
8685 | @item |
8686 | What compiler (and its version) was used to compile the program you | |
18fae2a8 | 8687 | are debugging---e.g. ``@value{GCC}--2.0''. |
ddf21240 | 8688 | |
70b88761 RP |
8689 | @item |
8690 | The command arguments you gave the compiler to compile your example and | |
8691 | observe the bug. For example, did you use @samp{-O}? To guarantee | |
1041a570 | 8692 | you will not omit something important, list them all. A copy of the |
ddf21240 | 8693 | Makefile (or the output from make) is sufficient. |
70b88761 RP |
8694 | |
8695 | If we were to try to guess the arguments, we would probably guess wrong | |
8696 | and then we might not encounter the bug. | |
8697 | ||
8698 | @item | |
ddf21240 JG |
8699 | A complete input script, and all necessary source files, that will |
8700 | reproduce the bug. | |
70b88761 RP |
8701 | |
8702 | @item | |
8703 | A description of what behavior you observe that you believe is | |
8704 | incorrect. For example, ``It gets a fatal signal.'' | |
8705 | ||
18fae2a8 | 8706 | Of course, if the bug is that @value{GDBN} gets a fatal signal, then we will |
70b88761 | 8707 | certainly notice it. But if the bug is incorrect output, we might not |
af215b1a VM |
8708 | notice unless it is glaringly wrong. You might as well not give us a |
8709 | chance to make a mistake. | |
70b88761 RP |
8710 | |
8711 | Even if the problem you experience is a fatal signal, you should still | |
8712 | say so explicitly. Suppose something strange is going on, such as, | |
18fae2a8 | 8713 | your copy of @value{GDBN} is out of synch, or you have encountered a |
70b88761 RP |
8714 | bug in the C library on your system. (This has happened!) Your copy |
8715 | might crash and ours would not. If you told us to expect a crash, | |
8716 | then when ours fails to crash, we would know that the bug was not | |
8717 | happening for us. If you had not told us to expect a crash, then we | |
8718 | would not be able to draw any conclusion from our observations. | |
8719 | ||
8720 | @item | |
18fae2a8 RP |
8721 | If you wish to suggest changes to the @value{GDBN} source, send us context |
8722 | diffs. If you even discuss something in the @value{GDBN} source, refer to | |
70b88761 RP |
8723 | it by context, not by line number. |
8724 | ||
1041a570 | 8725 | The line numbers in our development sources will not match those in your |
70b88761 | 8726 | sources. Your line numbers would convey no useful information to us. |
70b88761 RP |
8727 | @end itemize |
8728 | ||
8729 | Here are some things that are not necessary: | |
8730 | ||
8731 | @itemize @bullet | |
8732 | @item | |
8733 | A description of the envelope of the bug. | |
8734 | ||
8735 | Often people who encounter a bug spend a lot of time investigating | |
8736 | which changes to the input file will make the bug go away and which | |
8737 | changes will not affect it. | |
8738 | ||
8739 | This is often time consuming and not very useful, because the way we | |
8740 | will find the bug is by running a single example under the debugger | |
8741 | with breakpoints, not by pure deduction from a series of examples. | |
8742 | We recommend that you save your time for something else. | |
8743 | ||
8744 | Of course, if you can find a simpler example to report @emph{instead} | |
8745 | of the original one, that is a convenience for us. Errors in the | |
8746 | output will be easier to spot, running under the debugger will take | |
b1955f0b | 8747 | less time, and so on. |
70b88761 | 8748 | |
29a2b744 | 8749 | However, simplification is not vital; if you do not want to do this, |
70b88761 RP |
8750 | report the bug anyway and send us the entire test case you used. |
8751 | ||
8752 | @item | |
8753 | A patch for the bug. | |
8754 | ||
29a2b744 | 8755 | A patch for the bug does help us if it is a good one. But do not omit |
70b88761 RP |
8756 | the necessary information, such as the test case, on the assumption that |
8757 | a patch is all we need. We might see problems with your patch and decide | |
8758 | to fix the problem another way, or we might not understand it at all. | |
8759 | ||
18fae2a8 | 8760 | Sometimes with a program as complicated as @value{GDBN} it is very hard to |
70b88761 | 8761 | construct an example that will make the program follow a certain path |
1041a570 RP |
8762 | through the code. If you do not send us the example, we will not be able |
8763 | to construct one, so we will not be able to verify that the bug is fixed. | |
70b88761 | 8764 | |
29a2b744 | 8765 | And if we cannot understand what bug you are trying to fix, or why your |
1041a570 | 8766 | patch should be an improvement, we will not install it. A test case will |
70b88761 RP |
8767 | help us to understand. |
8768 | ||
8769 | @item | |
8770 | A guess about what the bug is or what it depends on. | |
8771 | ||
29a2b744 | 8772 | Such guesses are usually wrong. Even we cannot guess right about such |
70b88761 RP |
8773 | things without first using the debugger to find the facts. |
8774 | @end itemize | |
8775 | ||
da24340c RP |
8776 | @c The readline documentation is distributed with the readline code |
8777 | @c and consists of the two following files: | |
8778 | @c rluser.texinfo | |
8779 | @c inc-hist.texi | |
8780 | @c Use -I with makeinfo to point to the appropriate directory, | |
8781 | @c environment var TEXINPUTS with TeX. | |
cacf5942 RP |
8782 | @include rluser.texinfo |
8783 | @include inc-hist.texi | |
70b88761 | 8784 | |
18fae2a8 | 8785 | @ifset NOVEL |
af215b1a | 8786 | @ifset RENAMED |
4eb4cf57 | 8787 | @node Renamed Commands |
70b88761 RP |
8788 | @appendix Renamed Commands |
8789 | ||
af215b1a | 8790 | The following commands were renamed in @value{GDBN} 4, in order to make the |
70b88761 RP |
8791 | command set as a whole more consistent and easier to use and remember: |
8792 | ||
e251e767 RP |
8793 | @kindex add-syms |
8794 | @kindex delete environment | |
8795 | @kindex info copying | |
8796 | @kindex info convenience | |
8797 | @kindex info directories | |
8798 | @kindex info editing | |
8799 | @kindex info history | |
8800 | @kindex info targets | |
8801 | @kindex info values | |
8802 | @kindex info version | |
8803 | @kindex info warranty | |
8804 | @kindex set addressprint | |
8805 | @kindex set arrayprint | |
8806 | @kindex set prettyprint | |
8807 | @kindex set screen-height | |
8808 | @kindex set screen-width | |
8809 | @kindex set unionprint | |
8810 | @kindex set vtblprint | |
8811 | @kindex set demangle | |
8812 | @kindex set asm-demangle | |
8813 | @kindex set sevenbit-strings | |
8814 | @kindex set array-max | |
8815 | @kindex set caution | |
8816 | @kindex set history write | |
8817 | @kindex show addressprint | |
8818 | @kindex show arrayprint | |
8819 | @kindex show prettyprint | |
8820 | @kindex show screen-height | |
8821 | @kindex show screen-width | |
8822 | @kindex show unionprint | |
8823 | @kindex show vtblprint | |
8824 | @kindex show demangle | |
8825 | @kindex show asm-demangle | |
8826 | @kindex show sevenbit-strings | |
8827 | @kindex show array-max | |
8828 | @kindex show caution | |
8829 | @kindex show history write | |
8830 | @kindex unset | |
70b88761 | 8831 | |
92b73793 | 8832 | @c TEXI2ROFF-KILL |
70b88761 | 8833 | @ifinfo |
92b73793 | 8834 | @c END TEXI2ROFF-KILL |
cf496415 RP |
8835 | @example |
8836 | OLD COMMAND NEW COMMAND | |
92b73793 | 8837 | @c TEXI2ROFF-KILL |
cf496415 | 8838 | --------------- ------------------------------- |
92b73793 | 8839 | @c END TEXI2ROFF-KILL |
cf496415 RP |
8840 | add-syms add-symbol-file |
8841 | delete environment unset environment | |
8842 | info convenience show convenience | |
8843 | info copying show copying | |
e251e767 | 8844 | info directories show directories |
cf496415 RP |
8845 | info editing show commands |
8846 | info history show values | |
8847 | info targets help target | |
8848 | info values show values | |
8849 | info version show version | |
8850 | info warranty show warranty | |
8851 | set/show addressprint set/show print address | |
8852 | set/show array-max set/show print elements | |
8853 | set/show arrayprint set/show print array | |
8854 | set/show asm-demangle set/show print asm-demangle | |
8855 | set/show caution set/show confirm | |
8856 | set/show demangle set/show print demangle | |
8857 | set/show history write set/show history save | |
8858 | set/show prettyprint set/show print pretty | |
8859 | set/show screen-height set/show height | |
8860 | set/show screen-width set/show width | |
8861 | set/show sevenbit-strings set/show print sevenbit-strings | |
8862 | set/show unionprint set/show print union | |
8863 | set/show vtblprint set/show print vtbl | |
8864 | ||
8865 | unset [No longer an alias for delete] | |
8866 | @end example | |
92b73793 | 8867 | @c TEXI2ROFF-KILL |
70b88761 RP |
8868 | @end ifinfo |
8869 | ||
8870 | @tex | |
8871 | \vskip \parskip\vskip \baselineskip | |
8872 | \halign{\tt #\hfil &\qquad#&\tt #\hfil\cr | |
8873 | {\bf Old Command} &&{\bf New Command}\cr | |
8874 | add-syms &&add-symbol-file\cr | |
8875 | delete environment &&unset environment\cr | |
8876 | info convenience &&show convenience\cr | |
8877 | info copying &&show copying\cr | |
8878 | info directories &&show directories \cr | |
8879 | info editing &&show commands\cr | |
8880 | info history &&show values\cr | |
8881 | info targets &&help target\cr | |
8882 | info values &&show values\cr | |
8883 | info version &&show version\cr | |
8884 | info warranty &&show warranty\cr | |
8885 | set{\rm / }show addressprint &&set{\rm / }show print address\cr | |
8886 | set{\rm / }show array-max &&set{\rm / }show print elements\cr | |
8887 | set{\rm / }show arrayprint &&set{\rm / }show print array\cr | |
8888 | set{\rm / }show asm-demangle &&set{\rm / }show print asm-demangle\cr | |
8889 | set{\rm / }show caution &&set{\rm / }show confirm\cr | |
8890 | set{\rm / }show demangle &&set{\rm / }show print demangle\cr | |
8891 | set{\rm / }show history write &&set{\rm / }show history save\cr | |
8892 | set{\rm / }show prettyprint &&set{\rm / }show print pretty\cr | |
8893 | set{\rm / }show screen-height &&set{\rm / }show height\cr | |
8894 | set{\rm / }show screen-width &&set{\rm / }show width\cr | |
8895 | set{\rm / }show sevenbit-strings &&set{\rm / }show print sevenbit-strings\cr | |
8896 | set{\rm / }show unionprint &&set{\rm / }show print union\cr | |
8897 | set{\rm / }show vtblprint &&set{\rm / }show print vtbl\cr | |
8898 | \cr | |
8899 | unset &&\rm(No longer an alias for delete)\cr | |
8900 | } | |
8901 | @end tex | |
92b73793 | 8902 | @c END TEXI2ROFF-KILL |
18fae2a8 | 8903 | @end ifset |
af215b1a | 8904 | @end ifset |
70b88761 | 8905 | |
18fae2a8 | 8906 | @ifclear PRECONFIGURED |
4eb4cf57 | 8907 | @node Formatting Documentation |
fe715d06 | 8908 | @appendix Formatting Documentation |
77b46d13 | 8909 | |
af215b1a | 8910 | @cindex @value{GDBN} reference card |
77b46d13 | 8911 | @cindex reference card |
af215b1a | 8912 | The @value{GDBN} 4 release includes an already-formatted reference card, ready |
d241c8c8 | 8913 | for printing with PostScript or Ghostscript, in the @file{gdb} |
ed447b95 RP |
8914 | subdirectory of the main source directory@footnote{In |
8915 | @file{gdb-@value{GDBVN}/gdb/refcard.ps} of the version @value{GDBVN} | |
d241c8c8 | 8916 | release.}. If you can use PostScript or Ghostscript with your printer, |
ed447b95 | 8917 | you can print the reference card immediately with @file{refcard.ps}. |
77b46d13 JG |
8918 | |
8919 | The release also includes the source for the reference card. You | |
8920 | can format it, using @TeX{}, by typing: | |
8921 | ||
8922 | @example | |
8923 | make refcard.dvi | |
8924 | @end example | |
8925 | ||
af215b1a VM |
8926 | The @value{GDBN} reference card is designed to print in @dfn{landscape} |
8927 | mode on US ``letter'' size paper; | |
8928 | that is, on a sheet 11 inches wide by 8.5 inches | |
77b46d13 JG |
8929 | high. You will need to specify this form of printing as an option to |
8930 | your @sc{dvi} output program. | |
8931 | ||
8932 | @cindex documentation | |
8933 | ||
af215b1a | 8934 | All the documentation for @value{GDBN} comes as part of the machine-readable |
77b46d13 JG |
8935 | distribution. The documentation is written in Texinfo format, which is |
8936 | a documentation system that uses a single source file to produce both | |
8937 | on-line information and a printed manual. You can use one of the Info | |
8938 | formatting commands to create the on-line version of the documentation | |
8939 | and @TeX{} (or @code{texi2roff}) to typeset the printed version. | |
8940 | ||
af215b1a | 8941 | @value{GDBN} includes an already formatted copy of the on-line Info version of |
77b46d13 | 8942 | this manual in the @file{gdb} subdirectory. The main Info file is |
af215b1a | 8943 | @file{gdb-@r{version-number}/gdb/gdb.info}, and it refers to |
a89f94c2 RP |
8944 | subordinate files matching @samp{gdb.info*} in the same directory. If |
8945 | necessary, you can print out these files, or read them with any editor; | |
af215b1a VM |
8946 | but they are easier to read using the @code{info} subsystem in @sc{gnu} Emacs |
8947 | or the standalone @code{info} program, available as part of the @sc{gnu} | |
a89f94c2 | 8948 | Texinfo distribution. |
77b46d13 JG |
8949 | |
8950 | If you want to format these Info files yourself, you need one of the | |
8951 | Info formatting programs, such as @code{texinfo-format-buffer} or | |
8952 | @code{makeinfo}. | |
8953 | ||
af215b1a | 8954 | If you have @code{makeinfo} installed, and are in the top level @value{GDBN} |
18fae2a8 | 8955 | source directory (@file{gdb-@value{GDBVN}}, in the case of version @value{GDBVN}), you can |
77b46d13 JG |
8956 | make the Info file by typing: |
8957 | ||
8958 | @example | |
8959 | cd gdb | |
8960 | make gdb.info | |
8961 | @end example | |
8962 | ||
fe715d06 RP |
8963 | If you want to typeset and print copies of this manual, you need @TeX{}, |
8964 | a program to print its @sc{dvi} output files, and @file{texinfo.tex}, the | |
8965 | Texinfo definitions file. | |
77b46d13 | 8966 | |
83bfcbae | 8967 | @TeX{} is a typesetting program; it does not print files directly, but |
77b46d13 JG |
8968 | produces output files called @sc{dvi} files. To print a typeset |
8969 | document, you need a program to print @sc{dvi} files. If your system | |
8970 | has @TeX{} installed, chances are it has such a program. The precise | |
8971 | command to use depends on your system; @kbd{lpr -d} is common; another | |
fe715d06 RP |
8972 | (for PostScript devices) is @kbd{dvips}. The @sc{dvi} print command may |
8973 | require a file name without any extension or a @samp{.dvi} extension. | |
77b46d13 JG |
8974 | |
8975 | @TeX{} also requires a macro definitions file called | |
8976 | @file{texinfo.tex}. This file tells @TeX{} how to typeset a document | |
af215b1a | 8977 | written in Texinfo format. On its own, @TeX{} cannot either read or |
77b46d13 JG |
8978 | typeset a Texinfo file. @file{texinfo.tex} is distributed with GDB |
8979 | and is located in the @file{gdb-@var{version-number}/texinfo} | |
8980 | directory. | |
8981 | ||
8982 | If you have @TeX{} and a @sc{dvi} printer program installed, you can | |
8983 | typeset and print this manual. First switch to the the @file{gdb} | |
8984 | subdirectory of the main source directory (for example, to | |
18fae2a8 | 8985 | @file{gdb-@value{GDBVN}/gdb}) and then type: |
77b46d13 JG |
8986 | |
8987 | @example | |
8988 | make gdb.dvi | |
8989 | @end example | |
8990 | ||
4eb4cf57 | 8991 | @node Installing GDB |
af215b1a VM |
8992 | @appendix Installing @value{GDBN} |
8993 | @cindex configuring @value{GDBN} | |
70b88761 RP |
8994 | @cindex installation |
8995 | ||
af215b1a VM |
8996 | @value{GDBN} comes with a @code{configure} script that automates the process |
8997 | of preparing @value{GDBN} for installation; you can then use @code{make} to | |
ed447b95 | 8998 | build the @code{gdb} program. |
f672bb7f RP |
8999 | @iftex |
9000 | @c irrelevant in info file; it's as current as the code it lives with. | |
af215b1a | 9001 | @footnote{If you have a more recent version of @value{GDBN} than @value{GDBVN}, |
ed447b95 RP |
9002 | look at the @file{README} file in the sources; we may have improved the |
9003 | installation procedures since publishing this manual.} | |
f672bb7f RP |
9004 | @end iftex |
9005 | ||
af215b1a VM |
9006 | The @value{GDBN} distribution includes all the source code you need for |
9007 | @value{GDBN} in a single directory, whose name is usually composed by | |
9008 | appending the version number to @samp{gdb}. | |
1041a570 | 9009 | |
af215b1a | 9010 | For example, the @value{GDBN} version @value{GDBVN} distribution is in the |
ed447b95 | 9011 | @file{gdb-@value{GDBVN}} directory. That directory contains: |
b80282d5 | 9012 | |
3d3ab540 | 9013 | @table @code |
18fae2a8 | 9014 | @item gdb-@value{GDBVN}/configure @r{(and supporting files)} |
af215b1a | 9015 | script for configuring @value{GDBN} and all its supporting libraries |
b80282d5 | 9016 | |
18fae2a8 | 9017 | @item gdb-@value{GDBVN}/gdb |
af215b1a | 9018 | the source specific to @value{GDBN} itself |
3d3ab540 | 9019 | |
18fae2a8 | 9020 | @item gdb-@value{GDBVN}/bfd |
77b46d13 | 9021 | source for the Binary File Descriptor library |
3d3ab540 | 9022 | |
18fae2a8 | 9023 | @item gdb-@value{GDBVN}/include |
af215b1a | 9024 | @sc{gnu} include files |
3d3ab540 | 9025 | |
18fae2a8 | 9026 | @item gdb-@value{GDBVN}/libiberty |
3d3ab540 RP |
9027 | source for the @samp{-liberty} free software library |
9028 | ||
18fae2a8 | 9029 | @item gdb-@value{GDBVN}/opcodes |
3214c51c JG |
9030 | source for the library of opcode tables and disassemblers |
9031 | ||
18fae2a8 | 9032 | @item gdb-@value{GDBVN}/readline |
af215b1a | 9033 | source for the @sc{gnu} command-line interface |
77b46d13 | 9034 | |
18fae2a8 | 9035 | @item gdb-@value{GDBVN}/glob |
af215b1a | 9036 | source for the @sc{gnu} filename pattern-matching subroutine |
77b46d13 | 9037 | |
18fae2a8 | 9038 | @item gdb-@value{GDBVN}/mmalloc |
af215b1a | 9039 | source for the @sc{gnu} memory-mapped malloc package |
3d3ab540 | 9040 | @end table |
1041a570 | 9041 | |
af215b1a | 9042 | The simplest way to configure and build @value{GDBN} is to run @code{configure} |
1041a570 | 9043 | from the @file{gdb-@var{version-number}} source directory, which in |
18fae2a8 | 9044 | this example is the @file{gdb-@value{GDBVN}} directory. |
1041a570 RP |
9045 | |
9046 | First switch to the @file{gdb-@var{version-number}} source directory | |
9047 | if you are not already in it; then run @code{configure}. Pass the | |
af215b1a | 9048 | identifier for the platform on which @value{GDBN} will run as an |
1041a570 RP |
9049 | argument. |
9050 | ||
9051 | For example: | |
9052 | ||
7463aadd | 9053 | @example |
18fae2a8 | 9054 | cd gdb-@value{GDBVN} |
3d3ab540 | 9055 | ./configure @var{host} |
7463aadd RP |
9056 | make |
9057 | @end example | |
1041a570 | 9058 | |
7463aadd | 9059 | @noindent |
1041a570 | 9060 | where @var{host} is an identifier such as @samp{sun4} or |
af215b1a | 9061 | @samp{decstation}, that identifies the platform where @value{GDBN} will run. |
d55320a0 RP |
9062 | (You can often leave off @var{host}; @code{configure} tries to guess the |
9063 | correct value by examining your system.) | |
1041a570 | 9064 | |
8c69096b | 9065 | Running @samp{configure @var{host}} and then running @code{make} builds the |
38962738 RP |
9066 | @file{bfd}, @file{readline}, @file{mmalloc}, and @file{libiberty} |
9067 | libraries, then @code{gdb} itself. The configured source files, and the | |
9068 | binaries, are left in the corresponding source directories. | |
3d3ab540 | 9069 | |
af215b1a | 9070 | @need 750 |
e251e767 | 9071 | @code{configure} is a Bourne-shell (@code{/bin/sh}) script; if your |
29a2b744 | 9072 | system does not recognize this automatically when you run a different |
1041a570 RP |
9073 | shell, you may need to run @code{sh} on it explicitly: |
9074 | ||
9075 | @example | |
9076 | sh configure @var{host} | |
9077 | @end example | |
e251e767 | 9078 | |
f672bb7f RP |
9079 | If you run @code{configure} from a directory that contains source |
9080 | directories for multiple libraries or programs, such as the | |
18fae2a8 | 9081 | @file{gdb-@value{GDBVN}} source directory for version @value{GDBVN}, @code{configure} |
f672bb7f | 9082 | creates configuration files for every directory level underneath (unless |
98349959 | 9083 | you tell it not to, with the @samp{--norecursion} option). |
f672bb7f RP |
9084 | |
9085 | You can run the @code{configure} script from any of the | |
af215b1a | 9086 | subordinate directories in the @value{GDBN} distribution if you only want to |
d55320a0 | 9087 | configure that subdirectory, but be sure to specify a path to it. |
1041a570 | 9088 | |
18fae2a8 | 9089 | For example, with version @value{GDBVN}, type the following to configure only |
1041a570 RP |
9090 | the @code{bfd} subdirectory: |
9091 | ||
e251e767 | 9092 | @example |
203eea5d | 9093 | @group |
18fae2a8 | 9094 | cd gdb-@value{GDBVN}/bfd |
e251e767 | 9095 | ../configure @var{host} |
203eea5d | 9096 | @end group |
e251e767 RP |
9097 | @end example |
9098 | ||
18fae2a8 | 9099 | You can install @code{@value{GDBP}} anywhere; it has no hardwired paths. |
1041a570 RP |
9100 | However, you should make sure that the shell on your path (named by |
9101 | the @samp{SHELL} environment variable) is publicly readable. Remember | |
af215b1a VM |
9102 | that @value{GDBN} uses the shell to start your program---some systems refuse to |
9103 | let @value{GDBN} debug child processes whose programs are not readable. | |
3d3ab540 RP |
9104 | |
9105 | @menu | |
af215b1a | 9106 | * Separate Objdir:: Compiling @value{GDBN} in another directory |
b80282d5 RP |
9107 | * Config Names:: Specifying names for hosts and targets |
9108 | * configure Options:: Summary of options for configure | |
3d3ab540 RP |
9109 | @end menu |
9110 | ||
4eb4cf57 | 9111 | @node Separate Objdir |
af215b1a | 9112 | @section Compiling @value{GDBN} in another directory |
1041a570 | 9113 | |
af215b1a | 9114 | If you want to run @value{GDBN} versions for several host or target machines, |
ed447b95 | 9115 | you need a different @code{gdb} compiled for each combination of |
1041a570 | 9116 | host and target. @code{configure} is designed to make this easy by |
f672bb7f RP |
9117 | allowing you to generate each configuration in a separate subdirectory, |
9118 | rather than in the source directory. If your @code{make} program | |
af215b1a | 9119 | handles the @samp{VPATH} feature (@sc{gnu} @code{make} does), running |
ed447b95 | 9120 | @code{make} in each of these directories builds the @code{gdb} |
f672bb7f | 9121 | program specified there. |
b80282d5 | 9122 | |
c7cb8acb | 9123 | To build @code{gdb} in a separate directory, run @code{configure} |
f672bb7f | 9124 | with the @samp{--srcdir} option to specify where to find the source. |
93918348 | 9125 | (You also need to specify a path to find @code{configure} |
77b46d13 JG |
9126 | itself from your working directory. If the path to @code{configure} |
9127 | would be the same as the argument to @samp{--srcdir}, you can leave out | |
9a27b06e | 9128 | the @samp{--srcdir} option; it is assumed.) |
1041a570 | 9129 | |
af215b1a VM |
9130 | For example, with version @value{GDBVN}, you can build @value{GDBN} in a |
9131 | separate directory for a Sun 4 like this: | |
70b88761 RP |
9132 | |
9133 | @example | |
3d3ab540 | 9134 | @group |
18fae2a8 | 9135 | cd gdb-@value{GDBVN} |
f672bb7f RP |
9136 | mkdir ../gdb-sun4 |
9137 | cd ../gdb-sun4 | |
18fae2a8 | 9138 | ../gdb-@value{GDBVN}/configure sun4 |
70b88761 | 9139 | make |
3d3ab540 | 9140 | @end group |
70b88761 RP |
9141 | @end example |
9142 | ||
f672bb7f RP |
9143 | When @code{configure} builds a configuration using a remote source |
9144 | directory, it creates a tree for the binaries with the same structure | |
9145 | (and using the same names) as the tree under the source directory. In | |
9146 | the example, you'd find the Sun 4 library @file{libiberty.a} in the | |
af215b1a | 9147 | directory @file{gdb-sun4/libiberty}, and @value{GDBN} itself in |
f672bb7f | 9148 | @file{gdb-sun4/gdb}. |
1041a570 | 9149 | |
af215b1a VM |
9150 | One popular reason to build several @value{GDBN} configurations in separate |
9151 | directories is to configure @value{GDBN} for cross-compiling (where | |
9152 | @value{GDBN} runs on one machine---the @dfn{host}---while debugging | |
9153 | programs that run on another machine---the @dfn{target}). | |
9154 | You specify a cross-debugging target by | |
f672bb7f | 9155 | giving the @samp{--target=@var{target}} option to @code{configure}. |
c7637ea6 | 9156 | |
1041a570 | 9157 | When you run @code{make} to build a program or library, you must run |
f672bb7f RP |
9158 | it in a configured directory---whatever directory you were in when you |
9159 | called @code{configure} (or one of its subdirectories). | |
c7637ea6 | 9160 | |
fe715d06 | 9161 | The @code{Makefile} that @code{configure} generates in each source |
f672bb7f | 9162 | directory also runs recursively. If you type @code{make} in a source |
18fae2a8 | 9163 | directory such as @file{gdb-@value{GDBVN}} (or in a separate configured |
b550c03a | 9164 | directory configured with @samp{--srcdir=@var{dirname}/gdb-@value{GDBVN}}), you |
ed447b95 | 9165 | will build all the required libraries, and then build GDB. |
3d3ab540 | 9166 | |
f672bb7f RP |
9167 | When you have multiple hosts or targets configured in separate |
9168 | directories, you can run @code{make} on them in parallel (for example, | |
9169 | if they are NFS-mounted on each of the hosts); they will not interfere | |
9170 | with each other. | |
3d3ab540 | 9171 | |
4eb4cf57 | 9172 | @node Config Names |
93928b60 | 9173 | @section Specifying names for hosts and targets |
b80282d5 RP |
9174 | |
9175 | The specifications used for hosts and targets in the @code{configure} | |
9176 | script are based on a three-part naming scheme, but some short predefined | |
9177 | aliases are also supported. The full naming scheme encodes three pieces | |
e251e767 | 9178 | of information in the following pattern: |
1041a570 | 9179 | |
b80282d5 RP |
9180 | @example |
9181 | @var{architecture}-@var{vendor}-@var{os} | |
9182 | @end example | |
9183 | ||
8c69096b RP |
9184 | For example, you can use the alias @code{sun4} as a @var{host} argument, |
9185 | or as the value for @var{target} in a @code{--target=@var{target}} | |
9186 | option. The equivalent full name is @samp{sparc-sun-sunos4}. | |
b80282d5 | 9187 | |
af215b1a | 9188 | The @code{configure} script accompanying @value{GDBN} does not provide |
b80282d5 RP |
9189 | any query facility to list all supported host and target names or |
9190 | aliases. @code{configure} calls the Bourne shell script | |
9191 | @code{config.sub} to map abbreviations to full names; you can read the | |
9192 | script, if you wish, or you can use it to test your guesses on | |
9193 | abbreviations---for example: | |
1041a570 | 9194 | |
b1385986 | 9195 | @smallexample |
b80282d5 | 9196 | % sh config.sub sun4 |
d55320a0 | 9197 | sparc-sun-sunos4.1.1 |
b80282d5 | 9198 | % sh config.sub sun3 |
d55320a0 | 9199 | m68k-sun-sunos4.1.1 |
b80282d5 | 9200 | % sh config.sub decstation |
d55320a0 | 9201 | mips-dec-ultrix4.2 |
b80282d5 RP |
9202 | % sh config.sub hp300bsd |
9203 | m68k-hp-bsd | |
9204 | % sh config.sub i386v | |
6a8cb0e7 | 9205 | i386-unknown-sysv |
e94b4a2b | 9206 | % sh config.sub i786v |
6a8cb0e7 | 9207 | Invalid configuration `i786v': machine `i786v' not recognized |
b1385986 | 9208 | @end smallexample |
1041a570 | 9209 | |
c7637ea6 | 9210 | @noindent |
af215b1a | 9211 | @code{config.sub} is also distributed in the @value{GDBN} source |
18fae2a8 | 9212 | directory (@file{gdb-@value{GDBVN}}, for version @value{GDBVN}). |
b80282d5 | 9213 | |
4eb4cf57 | 9214 | @node configure Options |
93928b60 | 9215 | @section @code{configure} options |
7463aadd | 9216 | |
d48da190 | 9217 | Here is a summary of the @code{configure} options and arguments that |
18fae2a8 | 9218 | are most often useful for building @value{GDBN}. @code{configure} also has |
d48da190 RP |
9219 | several other options not listed here. @inforef{What Configure |
9220 | Does,,configure.info}, for a full explanation of @code{configure}. | |
7463aadd RP |
9221 | |
9222 | @example | |
d48da190 RP |
9223 | configure @r{[}--help@r{]} |
9224 | @r{[}--prefix=@var{dir}@r{]} | |
b550c03a | 9225 | @r{[}--srcdir=@var{dirname}@r{]} |
f672bb7f RP |
9226 | @r{[}--norecursion@r{]} @r{[}--rm@r{]} |
9227 | @r{[}--target=@var{target}@r{]} @var{host} | |
7463aadd | 9228 | @end example |
1041a570 | 9229 | |
3d3ab540 | 9230 | @noindent |
f672bb7f RP |
9231 | You may introduce options with a single @samp{-} rather than |
9232 | @samp{--} if you prefer; but you may abbreviate option names if you use | |
9233 | @samp{--}. | |
70b88761 RP |
9234 | |
9235 | @table @code | |
d48da190 RP |
9236 | @item --help |
9237 | Display a quick summary of how to invoke @code{configure}. | |
9238 | ||
9239 | @item -prefix=@var{dir} | |
9240 | Configure the source to install programs and files under directory | |
9241 | @file{@var{dir}}. | |
9242 | ||
b1955f0b RP |
9243 | @c avoid splitting the warning from the explanation: |
9244 | @need 2000 | |
b550c03a | 9245 | @item --srcdir=@var{dirname} |
af215b1a | 9246 | @strong{Warning: using this option requires @sc{gnu} @code{make}, or another |
6ca72cc6 | 9247 | @code{make} that implements the @code{VPATH} feature.}@* |
f672bb7f | 9248 | Use this option to make configurations in directories separate from the |
af215b1a | 9249 | @value{GDBN} source directories. Among other things, you can use this to |
f672bb7f RP |
9250 | build (or maintain) several configurations simultaneously, in separate |
9251 | directories. @code{configure} writes configuration specific files in | |
9252 | the current directory, but arranges for them to use the source in the | |
b550c03a | 9253 | directory @var{dirname}. @code{configure} creates directories under |
f672bb7f | 9254 | the working directory in parallel to the source directories below |
b550c03a | 9255 | @var{dirname}. |
f672bb7f RP |
9256 | |
9257 | @item --norecursion | |
9258 | Configure only the directory level where @code{configure} is executed; do not | |
7463aadd RP |
9259 | propagate configuration to subdirectories. |
9260 | ||
f672bb7f | 9261 | @item --rm |
d55320a0 | 9262 | @emph{Remove} files otherwise built during configuration. |
7463aadd | 9263 | |
29a2b744 | 9264 | @c This does not work (yet if ever). FIXME. |
f672bb7f | 9265 | @c @item --parse=@var{lang} @dots{} |
af215b1a VM |
9266 | @c Configure the @value{GDBN} expression parser to parse the listed languages. |
9267 | @c @samp{all} configures @value{GDBN} for all supported languages. To get a | |
d7b569d5 | 9268 | @c list of all supported languages, omit the argument. Without this |
af215b1a | 9269 | @c option, @value{GDBN} is configured to parse all supported languages. |
c2bbbb22 | 9270 | |
f672bb7f | 9271 | @item --target=@var{target} |
af215b1a VM |
9272 | Configure @value{GDBN} for cross-debugging programs running on the specified |
9273 | @var{target}. Without this option, @value{GDBN} is configured to debug | |
9274 | programs that run on the same machine (@var{host}) as @value{GDBN} itself. | |
b80282d5 RP |
9275 | |
9276 | There is no convenient way to generate a list of all available targets. | |
7463aadd RP |
9277 | |
9278 | @item @var{host} @dots{} | |
af215b1a | 9279 | Configure @value{GDBN} to run on the specified @var{host}. |
b80282d5 RP |
9280 | |
9281 | There is no convenient way to generate a list of all available hosts. | |
70b88761 RP |
9282 | @end table |
9283 | ||
3d3ab540 RP |
9284 | @noindent |
9285 | @code{configure} accepts other options, for compatibility with | |
af215b1a VM |
9286 | configuring other @sc{gnu} tools recursively; but these are the only |
9287 | options that affect @value{GDBN} or its supporting libraries. | |
18fae2a8 | 9288 | @end ifclear |
3d3ab540 | 9289 | |
4eb4cf57 | 9290 | @node Index |
d2e08421 | 9291 | @unnumbered Index |
e91b87a3 | 9292 | |
9293 | @printindex cp | |
9294 | ||
fe3f5fc8 RP |
9295 | @tex |
9296 | % I think something like @colophon should be in texinfo. In the | |
9297 | % meantime: | |
9298 | \long\def\colophon{\hbox to0pt{}\vfill | |
9299 | \centerline{The body of this manual is set in} | |
9300 | \centerline{\fontname\tenrm,} | |
9301 | \centerline{with headings in {\bf\fontname\tenbf}} | |
9302 | \centerline{and examples in {\tt\fontname\tentt}.} | |
a6d0b6d3 RP |
9303 | \centerline{{\it\fontname\tenit\/},} |
9304 | \centerline{{\bf\fontname\tenbf}, and} | |
fe3f5fc8 RP |
9305 | \centerline{{\sl\fontname\tensl\/}} |
9306 | \centerline{are used for emphasis.}\vfill} | |
9307 | \page\colophon | |
e0d3ace2 | 9308 | % Blame: doc@cygnus.com, 1991. |
fe3f5fc8 RP |
9309 | @end tex |
9310 | ||
e91b87a3 | 9311 | @contents |
9312 | @bye |