1 \input texinfo @c -*- Texinfo -*-
2 @setfilename binutils.info
8 * Binutils: (binutils). The GNU binary utilities "ar", "objcopy",
9 "objdump", "nm", "nlmconv", "size",
10 "strings", "strip", and "ranlib".
16 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
18 Permission is granted to make and distribute verbatim copies of
19 this manual provided the copyright notice and this permission notice
20 are preserved on all copies.
23 Permission is granted to process this file through TeX and print the
24 results, provided the printed document carries a copying permission
25 notice identical to this one except for the removal of this paragraph
26 (this paragraph not being relevant to the printed manual).
30 Permission is granted to copy and distribute modified versions of this
31 manual under the conditions for verbatim copying, provided also that
32 the entire resulting derived work is distributed under the terms of a
33 permission notice identical to this one.
35 Permission is granted to copy and distribute translations of this manual
36 into another language, under the above conditions for modified versions.
41 @c This file documents the GNU binary utilities "ar", "ld", "objcopy",
42 @c "objdump", "nm", "size", "strings", "strip", and "ranlib".
44 @c Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
46 @c This text may be freely distributed under the terms of the GNU
47 @c General Public License.
50 @setchapternewpage odd
51 @settitle @sc{gnu} Binary Utilities
54 @title The @sc{gnu} Binary Utilities
55 @subtitle Version @value{VERSION}
58 @author Roland H. Pesch
59 @author Jeffrey M. Osier
60 @author Cygnus Support
64 {\parskip=0pt \hfill Cygnus Support\par \hfill
65 \TeX{}info \texinfoversion\par }
68 @vskip 0pt plus 1filll
69 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
71 Permission is granted to make and distribute verbatim copies of
72 this manual provided the copyright notice and this permission notice
73 are preserved on all copies.
75 Permission is granted to copy and distribute modified versions of this
76 manual under the conditions for verbatim copying, provided also that
77 the entire resulting derived work is distributed under the terms of a
78 permission notice identical to this one.
80 Permission is granted to copy and distribute translations of this manual
81 into another language, under the above conditions for modified versions.
88 This brief manual contains preliminary documentation for the @sc{gnu} binary
89 utilities (collectively version @value{VERSION}):
94 Create, modify, and extract from archives
97 List symbols from object files
100 Copy and translate object files
103 Display information from object files
106 Generate index to archive contents
109 List file section sizes and total size
112 List printable strings from files
118 Demangle encoded C++ symbols
121 Convert addresses into file names and line numbers
124 Convert object code into a Netware Loadable Module
127 Manipulate Windows resources
132 * ar:: Create, modify, and extract from archives
133 * nm:: List symbols from object files
134 * objcopy:: Copy and translate object files
135 * objdump:: Display information from object files
136 * ranlib:: Generate index to archive contents
137 * size:: List section sizes and total size
138 * strings:: List printable strings from files
139 * strip:: Discard symbols
140 * c++filt:: Filter to demangle encoded C++ symbols
141 * addr2line:: Convert addresses to file and line
142 * nlmconv:: Converts object code into an NLM
143 * windres:: Manipulate Windows resources
144 * Selecting The Target System:: How these utilities determine the target.
145 * Reporting Bugs:: Reporting Bugs
154 @cindex collections of files
156 ar [-]@var{p}[@var{mod} [@var{relpos}]] @var{archive} [@var{member}@dots{}]
157 ar -M [ <mri-script ]
160 The @sc{gnu} @code{ar} program creates, modifies, and extracts from
161 archives. An @dfn{archive} is a single file holding a collection of
162 other files in a structure that makes it possible to retrieve
163 the original individual files (called @dfn{members} of the archive).
165 The original files' contents, mode (permissions), timestamp, owner, and
166 group are preserved in the archive, and can be restored on
170 @sc{gnu} @code{ar} can maintain archives whose members have names of any
171 length; however, depending on how @code{ar} is configured on your
172 system, a limit on member-name length may be imposed for compatibility
173 with archive formats maintained with other tools. If it exists, the
174 limit is often 15 characters (typical of formats related to a.out) or 16
175 characters (typical of formats related to coff).
178 @code{ar} is considered a binary utility because archives of this sort
179 are most often used as @dfn{libraries} holding commonly needed
183 @code{ar} creates an index to the symbols defined in relocatable
184 object modules in the archive when you specify the modifier @samp{s}.
185 Once created, this index is updated in the archive whenever @code{ar}
186 makes a change to its contents (save for the @samp{q} update operation).
187 An archive with such an index speeds up linking to the library, and
188 allows routines in the library to call each other without regard to
189 their placement in the archive.
191 You may use @samp{nm -s} or @samp{nm --print-armap} to list this index
192 table. If an archive lacks the table, another form of @code{ar} called
193 @code{ranlib} can be used to add just the table.
195 @cindex compatibility, @code{ar}
196 @cindex @code{ar} compatibility
197 @sc{gnu} @code{ar} is designed to be compatible with two different
198 facilities. You can control its activity using command-line options,
199 like the different varieties of @code{ar} on Unix systems; or, if you
200 specify the single command-line option @samp{-M}, you can control it
201 with a script supplied via standard input, like the MRI ``librarian''
205 * ar cmdline:: Controlling @code{ar} on the command line
206 * ar scripts:: Controlling @code{ar} with a script
211 @section Controlling @code{ar} on the command line
214 ar [-]@var{p}[@var{mod} [@var{relpos}]] @var{archive} [@var{member}@dots{}]
217 @cindex Unix compatibility, @code{ar}
218 When you use @code{ar} in the Unix style, @code{ar} insists on at least two
219 arguments to execute: one keyletter specifying the @emph{operation}
220 (optionally accompanied by other keyletters specifying
221 @emph{modifiers}), and the archive name to act on.
223 Most operations can also accept further @var{member} arguments,
224 specifying particular files to operate on.
226 @sc{gnu} @code{ar} allows you to mix the operation code @var{p} and modifier
227 flags @var{mod} in any order, within the first command-line argument.
229 If you wish, you may begin the first command-line argument with a
232 @cindex operations on archive
233 The @var{p} keyletter specifies what operation to execute; it may be
234 any of the following, but you must specify only one of them:
238 @cindex deleting from archive
239 @emph{Delete} modules from the archive. Specify the names of modules to
240 be deleted as @var{member}@dots{}; the archive is untouched if you
241 specify no files to delete.
243 If you specify the @samp{v} modifier, @code{ar} lists each module
247 @cindex moving in archive
248 Use this operation to @emph{move} members in an archive.
250 The ordering of members in an archive can make a difference in how
251 programs are linked using the library, if a symbol is defined in more
254 If no modifiers are used with @code{m}, any members you name in the
255 @var{member} arguments are moved to the @emph{end} of the archive;
256 you can use the @samp{a}, @samp{b}, or @samp{i} modifiers to move them to a
257 specified place instead.
260 @cindex printing from archive
261 @emph{Print} the specified members of the archive, to the standard
262 output file. If the @samp{v} modifier is specified, show the member
263 name before copying its contents to standard output.
265 If you specify no @var{member} arguments, all the files in the archive are
269 @cindex quick append to archive
270 @emph{Quick append}; Historically, add the files @var{member}@dots{} to the end of
271 @var{archive}, without checking for replacement.
273 The modifiers @samp{a}, @samp{b}, and @samp{i} do @emph{not} affect this
274 operation; new members are always placed at the end of the archive.
276 The modifier @samp{v} makes @code{ar} list each file as it is appended.
278 Since the point of this operation is speed, the archive's symbol table
279 index is not updated, even if it already existed; you can use @samp{ar s} or
280 @code{ranlib} explicitly to update the symbol table index.
282 However, too many different system assume quick append rebuilds the
283 index, so GNU ar treats @code{q} to same way its treats @code{r}.
286 @cindex replacement in archive
287 Insert the files @var{member}@dots{} into @var{archive} (with
288 @emph{replacement}). This operation differs from @samp{q} in that any
289 previously existing members are deleted if their names match those being
292 If one of the files named in @var{member}@dots{} does not exist, @code{ar}
293 displays an error message, and leaves undisturbed any existing members
294 of the archive matching that name.
296 By default, new members are added at the end of the file; but you may
297 use one of the modifiers @samp{a}, @samp{b}, or @samp{i} to request
298 placement relative to some existing member.
300 The modifier @samp{v} used with this operation elicits a line of
301 output for each file inserted, along with one of the letters @samp{a} or
302 @samp{r} to indicate whether the file was appended (no old member
303 deleted) or replaced.
306 @cindex contents of archive
307 Display a @emph{table} listing the contents of @var{archive}, or those
308 of the files listed in @var{member}@dots{} that are present in the
309 archive. Normally only the member name is shown; if you also want to
310 see the modes (permissions), timestamp, owner, group, and size, you can
311 request that by also specifying the @samp{v} modifier.
313 If you do not specify a @var{member}, all files in the archive
316 @cindex repeated names in archive
317 @cindex name duplication in archive
318 If there is more than one file with the same name (say, @samp{fie}) in
319 an archive (say @samp{b.a}), @samp{ar t b.a fie} lists only the
320 first instance; to see them all, you must ask for a complete
321 listing---in our example, @samp{ar t b.a}.
322 @c WRS only; per Gumby, this is implementation-dependent, and in a more
323 @c recent case in fact works the other way.
326 @cindex extract from archive
327 @emph{Extract} members (named @var{member}) from the archive. You can
328 use the @samp{v} modifier with this operation, to request that
329 @code{ar} list each name as it extracts it.
331 If you do not specify a @var{member}, all files in the archive
336 A number of modifiers (@var{mod}) may immediately follow the @var{p}
337 keyletter, to specify variations on an operation's behavior:
341 @cindex relative placement in archive
342 Add new files @emph{after} an existing member of the
343 archive. If you use the modifier @samp{a}, the name of an existing archive
344 member must be present as the @var{relpos} argument, before the
345 @var{archive} specification.
348 Add new files @emph{before} an existing member of the
349 archive. If you use the modifier @samp{b}, the name of an existing archive
350 member must be present as the @var{relpos} argument, before the
351 @var{archive} specification. (same as @samp{i}).
354 @cindex creating archives
355 @emph{Create} the archive. The specified @var{archive} is always
356 created if it did not exist, when you request an update. But a warning is
357 issued unless you specify in advance that you expect to create it, by
361 Truncate names in the archive. @sc{gnu} @code{ar} will normally permit file
362 names of any length. This will cause it to create archives which are
363 not compatible with the native @code{ar} program on some systems. If
364 this is a concern, the @samp{f} modifier may be used to truncate file
365 names when putting them in the archive.
368 Insert new files @emph{before} an existing member of the
369 archive. If you use the modifier @samp{i}, the name of an existing archive
370 member must be present as the @var{relpos} argument, before the
371 @var{archive} specification. (same as @samp{b}).
374 This modifier is accepted but not used.
375 @c whaffor ar l modifier??? presumably compat; with
376 @c what???---doc@@cygnus.com, 25jan91
379 @cindex dates in archive
380 Preserve the @emph{original} dates of members when extracting them. If
381 you do not specify this modifier, files extracted from the archive
382 are stamped with the time of extraction.
385 @cindex writing archive index
386 Write an object-file index into the archive, or update an existing one,
387 even if no other change is made to the archive. You may use this modifier
388 flag either with any operation, or alone. Running @samp{ar s} on an
389 archive is equivalent to running @samp{ranlib} on it.
392 @cindex updating an archive
393 Normally, @samp{ar r}@dots{} inserts all files
394 listed into the archive. If you would like to insert @emph{only} those
395 of the files you list that are newer than existing members of the same
396 names, use this modifier. The @samp{u} modifier is allowed only for the
397 operation @samp{r} (replace). In particular, the combination @samp{qu} is
398 not allowed, since checking the timestamps would lose any speed
399 advantage from the operation @samp{q}.
402 This modifier requests the @emph{verbose} version of an operation. Many
403 operations display additional information, such as filenames processed,
404 when the modifier @samp{v} is appended.
407 This modifier shows the version number of @code{ar}.
411 @section Controlling @code{ar} with a script
414 ar -M [ <@var{script} ]
417 @cindex MRI compatibility, @code{ar}
418 @cindex scripts, @code{ar}
419 If you use the single command-line option @samp{-M} with @code{ar}, you
420 can control its operation with a rudimentary command language. This
421 form of @code{ar} operates interactively if standard input is coming
422 directly from a terminal. During interactive use, @code{ar} prompts for
423 input (the prompt is @samp{AR >}), and continues executing even after
424 errors. If you redirect standard input to a script file, no prompts are
425 issued, and @code{ar} abandons execution (with a nonzero exit code)
428 The @code{ar} command language is @emph{not} designed to be equivalent
429 to the command-line options; in fact, it provides somewhat less control
430 over archives. The only purpose of the command language is to ease the
431 transition to @sc{gnu} @code{ar} for developers who already have scripts
432 written for the MRI ``librarian'' program.
434 The syntax for the @code{ar} command language is straightforward:
437 commands are recognized in upper or lower case; for example, @code{LIST}
438 is the same as @code{list}. In the following descriptions, commands are
439 shown in upper case for clarity.
442 a single command may appear on each line; it is the first word on the
446 empty lines are allowed, and have no effect.
449 comments are allowed; text after either of the characters @samp{*}
450 or @samp{;} is ignored.
453 Whenever you use a list of names as part of the argument to an @code{ar}
454 command, you can separate the individual names with either commas or
455 blanks. Commas are shown in the explanations below, for clarity.
458 @samp{+} is used as a line continuation character; if @samp{+} appears
459 at the end of a line, the text on the following line is considered part
460 of the current command.
463 Here are the commands you can use in @code{ar} scripts, or when using
464 @code{ar} interactively. Three of them have special significance:
466 @code{OPEN} or @code{CREATE} specify a @dfn{current archive}, which is
467 a temporary file required for most of the other commands.
469 @code{SAVE} commits the changes so far specified by the script. Prior
470 to @code{SAVE}, commands affect only the temporary copy of the current
474 @item ADDLIB @var{archive}
475 @itemx ADDLIB @var{archive} (@var{module}, @var{module}, @dots{} @var{module})
476 Add all the contents of @var{archive} (or, if specified, each named
477 @var{module} from @var{archive}) to the current archive.
479 Requires prior use of @code{OPEN} or @code{CREATE}.
481 @item ADDMOD @var{member}, @var{member}, @dots{} @var{member}
482 @c FIXME! w/Replacement?? If so, like "ar r @var{archive} @var{names}"
483 @c else like "ar q..."
484 Add each named @var{member} as a module in the current archive.
486 Requires prior use of @code{OPEN} or @code{CREATE}.
489 Discard the contents of the current archive, cancelling the effect of
490 any operations since the last @code{SAVE}. May be executed (with no
491 effect) even if no current archive is specified.
493 @item CREATE @var{archive}
494 Creates an archive, and makes it the current archive (required for many
495 other commands). The new archive is created with a temporary name; it
496 is not actually saved as @var{archive} until you use @code{SAVE}.
497 You can overwrite existing archives; similarly, the contents of any
498 existing file named @var{archive} will not be destroyed until @code{SAVE}.
500 @item DELETE @var{module}, @var{module}, @dots{} @var{module}
501 Delete each listed @var{module} from the current archive; equivalent to
502 @samp{ar -d @var{archive} @var{module} @dots{} @var{module}}.
504 Requires prior use of @code{OPEN} or @code{CREATE}.
506 @item DIRECTORY @var{archive} (@var{module}, @dots{} @var{module})
507 @itemx DIRECTORY @var{archive} (@var{module}, @dots{} @var{module}) @var{outputfile}
508 List each named @var{module} present in @var{archive}. The separate
509 command @code{VERBOSE} specifies the form of the output: when verbose
510 output is off, output is like that of @samp{ar -t @var{archive}
511 @var{module}@dots{}}. When verbose output is on, the listing is like
512 @samp{ar -tv @var{archive} @var{module}@dots{}}.
514 Output normally goes to the standard output stream; however, if you
515 specify @var{outputfile} as a final argument, @code{ar} directs the
519 Exit from @code{ar}, with a @code{0} exit code to indicate successful
520 completion. This command does not save the output file; if you have
521 changed the current archive since the last @code{SAVE} command, those
524 @item EXTRACT @var{module}, @var{module}, @dots{} @var{module}
525 Extract each named @var{module} from the current archive, writing them
526 into the current directory as separate files. Equivalent to @samp{ar -x
527 @var{archive} @var{module}@dots{}}.
529 Requires prior use of @code{OPEN} or @code{CREATE}.
532 @c FIXME Tokens but no commands???
539 Display full contents of the current archive, in ``verbose'' style
540 regardless of the state of @code{VERBOSE}. The effect is like @samp{ar
541 tv @var{archive}}). (This single command is a @sc{gnu} @code{ld}
542 enhancement, rather than present for MRI compatibility.)
544 Requires prior use of @code{OPEN} or @code{CREATE}.
546 @item OPEN @var{archive}
547 Opens an existing archive for use as the current archive (required for
548 many other commands). Any changes as the result of subsequent commands
549 will not actually affect @var{archive} until you next use @code{SAVE}.
551 @item REPLACE @var{module}, @var{module}, @dots{} @var{module}
552 In the current archive, replace each existing @var{module} (named in
553 the @code{REPLACE} arguments) from files in the current working directory.
554 To execute this command without errors, both the file, and the module in
555 the current archive, must exist.
557 Requires prior use of @code{OPEN} or @code{CREATE}.
560 Toggle an internal flag governing the output from @code{DIRECTORY}.
561 When the flag is on, @code{DIRECTORY} output matches output from
562 @samp{ar -tv }@dots{}.
565 Commit your changes to the current archive, and actually save it as a
566 file with the name specified in the last @code{CREATE} or @code{OPEN}
569 Requires prior use of @code{OPEN} or @code{CREATE}.
578 The @sc{gnu} linker @code{ld} is now described in a separate manual.
579 @xref{Top,, Overview,, Using LD: the @sc{gnu} linker}.
588 nm [ -a | --debug-syms ] [ -g | --extern-only ]
589 [ -B ] [ -C | --demangle ] [ -D | --dynamic ]
590 [ -s | --print-armap ] [ -A | -o | --print-file-name ]
591 [ -n | -v | --numeric-sort ] [ -p | --no-sort ]
592 [ -r | --reverse-sort ] [ --size-sort ] [ -u | --undefined-only ]
593 [ -t @var{radix} | --radix=@var{radix} ] [ -P | --portability ]
594 [ --target=@var{bfdname} ] [ -f @var{format} | --format=@var{format} ]
595 [ --defined-only ] [-l | --line-numbers ]
596 [ --no-demangle ] [ -V | --version ] [ --help ] [ @var{objfile}@dots{} ]
599 @sc{gnu} @code{nm} lists the symbols from object files @var{objfile}@dots{}.
600 If no object files are listed as arguments, @code{nm} assumes
603 For each symbol, @code{nm} shows:
607 The symbol value, in the radix selected by options (see below), or
608 hexadecimal by default.
611 The symbol type. At least the following types are used; others are, as
612 well, depending on the object file format. If lowercase, the symbol is
613 local; if uppercase, the symbol is global (external).
615 @c Some more detail on exactly what these symbol types are used for
619 The symbol's value is absolute, and will not be changed by further
623 The symbol is in the uninitialized data section (known as BSS).
626 The symbol is common. Common symbols are uninitialized data. When
627 linking, multiple common symbols may appear with the same name. If the
628 symbol is defined anywhere, the common symbols are treated as undefined
629 references. For more details on common symbols, see the discussion of
630 --warn-common in @ref{Options,,Linker options,ld.info,The GNU linker}.
633 The symbol is in the initialized data section.
636 The symbol is in an initialized data section for small objects. Some
637 object file formats permit more efficient access to small data objects,
638 such as a global int variable as opposed to a large global array.
641 The symbol is an indirect reference to another symbol. This is a GNU
642 extension to the a.out object file format which is rarely used.
645 The symbol is a debugging symbol.
648 The symbol is in a read only data section.
651 The symbol is in an uninitialized data section for small objects.
654 The symbol is in the text (code) section.
657 The symbol is undefined.
660 The symbol is weak. When a weak defined symbol is linked with a normal
661 defined symbol, the normal defined symbol is used with no error. When a
662 weak undefined symbol is linked and the symbol is not defined, the value
663 of the weak symbol becomes zero with no error.
666 The symbol is a stabs symbol in an a.out object file. In this case, the
667 next values printed are the stabs other field, the stabs desc field, and
668 the stab type. Stabs symbols are used to hold debugging information;
669 for more information, see @ref{Top,Stabs,Stabs Overview,stabs.info, The
670 ``stabs'' debug format}.
673 The symbol type is unknown, or object file format specific.
680 The long and short forms of options, shown here as alternatives, are
686 @itemx --print-file-name
687 @cindex input file name
689 @cindex source file name
690 Precede each symbol by the name of the input file (or archive element)
691 in which it was found, rather than identifying the input file once only,
692 before all of its symbols.
696 @cindex debugging symbols
697 Display all symbols, even debugger-only symbols; normally these are not
701 @cindex @code{nm} format
702 @cindex @code{nm} compatibility
703 The same as @samp{--format=bsd} (for compatibility with the MIPS @code{nm}).
707 @cindex demangling in nm
708 Decode (@dfn{demangle}) low-level symbol names into user-level names.
709 Besides removing any initial underscore prepended by the system, this
710 makes C++ function names readable. @xref{c++filt}, for more information
714 Do not demangle low-level symbol names. This is the default.
718 @cindex dynamic symbols
719 Display the dynamic symbols rather than the normal symbols. This is
720 only meaningful for dynamic objects, such as certain types of shared
723 @item -f @var{format}
724 @itemx --format=@var{format}
725 @cindex @code{nm} format
726 @cindex @code{nm} compatibility
727 Use the output format @var{format}, which can be @code{bsd},
728 @code{sysv}, or @code{posix}. The default is @code{bsd}.
729 Only the first character of @var{format} is significant; it can be
730 either upper or lower case.
734 @cindex external symbols
735 Display only external symbols.
738 @itemx --line-numbers
739 @cindex symbol line numbers
740 For each symbol, use debugging information to try to find a filename and
741 line number. For a defined symbol, look for the line number of the
742 address of the symbol. For an undefined symbol, look for the line
743 number of a relocation entry which refers to the symbol. If line number
744 information can be found, print it after the other symbol information.
748 @itemx --numeric-sort
749 Sort symbols numerically by their addresses, rather than alphabetically
754 @cindex sorting symbols
755 Do not bother to sort the symbols in any order; print them in the order
760 Use the POSIX.2 standard output format instead of the default format.
761 Equivalent to @samp{-f posix}.
765 @cindex symbol index, listing
766 When listing symbols from archive members, include the index: a mapping
767 (stored in the archive by @code{ar} or @code{ranlib}) of which modules
768 contain definitions for which names.
771 @itemx --reverse-sort
772 Reverse the order of the sort (whether numeric or alphabetic); let the
776 Sort symbols by size. The size is computed as the difference between
777 the value of the symbol and the value of the symbol with the next higher
778 value. The size of the symbol is printed, rather than the value.
781 @itemx --radix=@var{radix}
782 Use @var{radix} as the radix for printing the symbol values. It must be
783 @samp{d} for decimal, @samp{o} for octal, or @samp{x} for hexadecimal.
785 @item --target=@var{bfdname}
786 @cindex object code format
787 Specify an object code format other than your system's default format.
788 @xref{Target Selection}, for more information.
791 @itemx --undefined-only
792 @cindex external symbols
793 @cindex undefined symbols
794 Display only undefined symbols (those external to each object file).
797 @cindex external symbols
798 @cindex undefined symbols
799 Display only defined symbols for each object file.
803 Show the version number of @code{nm} and exit.
806 Show a summary of the options to @code{nm} and exit.
813 objcopy [ -F @var{bfdname} | --target=@var{bfdname} ]
814 [ -I @var{bfdname} | --input-target=@var{bfdname} ]
815 [ -O @var{bfdname} | --output-target=@var{bfdname} ]
816 [ -S | --strip-all ] [ -g | --strip-debug ]
817 [ -K @var{symbolname} | --keep-symbol=@var{symbolname} ]
818 [ -N @var{symbolname} | --strip-symbol=@var{symbolname} ]
819 [ -L @var{symbolname} | --localize-symbol=@var{symbolname} ]
820 [ -W @var{symbolname} | --weaken-symbol=@var{symbolname} ]
821 [ -x | --discard-all ] [ -X | --discard-locals ]
822 [ -b @var{byte} | --byte=@var{byte} ]
823 [ -i @var{interleave} | --interleave=@var{interleave} ]
824 [ -R @var{sectionname} | --remove-section=@var{sectionname} ]
825 [ -p | --preserve-dates ] [ --debugging ]
826 [ --gap-fill=@var{val} ] [ --pad-to=@var{address} ]
827 [ --set-start=@var{val} ] [ --adjust-start=@var{incr} ]
828 [ --adjust-vma=@var{incr} ]
829 [ --adjust-section-vma=@var{section}@{=,+,-@}@var{val} ]
830 [ --adjust-warnings ] [ --no-adjust-warnings ]
831 [ --set-section-flags=@var{section}=@var{flags} ]
832 [ --add-section=@var{sectionname}=@var{filename} ]
833 [ --change-leading-char ] [ --remove-leading-char ]
835 [ -v | --verbose ] [ -V | --version ] [ --help ]
836 @var{infile} [@var{outfile}]
839 The @sc{gnu} @code{objcopy} utility copies the contents of an object
840 file to another. @code{objcopy} uses the @sc{gnu} @sc{bfd} Library to
841 read and write the object files. It can write the destination object
842 file in a format different from that of the source object file. The
843 exact behavior of @code{objcopy} is controlled by command-line options.
845 @code{objcopy} creates temporary files to do its translations and
846 deletes them afterward. @code{objcopy} uses @sc{bfd} to do all its
847 translation work; it has access to all the formats described in @sc{bfd}
848 and thus is able to recognize most formats without being told
849 explicitly. @xref{BFD,,BFD,ld.info,Using LD}.
851 @code{objcopy} can be used to generate S-records by using an output
852 target of @samp{srec} (e.g., use @samp{-O srec}).
854 @code{objcopy} can be used to generate a raw binary file by using an
855 output target of @samp{binary} (e.g., use @samp{-O binary}). When
856 @code{objcopy} generates a raw binary file, it will essentially produce
857 a memory dump of the contents of the input object file. All symbols and
858 relocation information will be discarded. The memory dump will start at
859 the load address of the lowest section copied into the output file.
861 When generating an S-record or a raw binary file, it may be helpful to
862 use @samp{-S} to remove sections containing debugging information. In
863 some cases @samp{-R} will be useful to remove sections which contain
864 information which is not needed by the binary file.
869 The source and output files, respectively.
870 If you do not specify @var{outfile}, @code{objcopy} creates a
871 temporary file and destructively renames the result with
872 the name of @var{infile}.
874 @item -I @var{bfdname}
875 @itemx --input-target=@var{bfdname}
876 Consider the source file's object format to be @var{bfdname}, rather than
877 attempting to deduce it. @xref{Target Selection}, for more information.
879 @item -O @var{bfdname}
880 @itemx --output-target=@var{bfdname}
881 Write the output file using the object format @var{bfdname}.
882 @xref{Target Selection}, for more information.
884 @item -F @var{bfdname}
885 @itemx --target=@var{bfdname}
886 Use @var{bfdname} as the object format for both the input and the output
887 file; i.e., simply transfer data from source to destination with no
888 translation. @xref{Target Selection}, for more information.
890 @item -R @var{sectionname}
891 @itemx --remove-section=@var{sectionname}
892 Remove any section named @var{sectionname} from the output file. This
893 option may be given more than once. Note that using this option
894 inappropriately may make the output file unusable.
898 Do not copy relocation and symbol information from the source file.
902 Do not copy debugging symbols from the source file.
904 @item --strip-unneeded
905 Strip all symbols that are not needed for relocation processing.
907 @item -K @var{symbolname}
908 @itemx --keep-symbol=@var{symbolname}
909 Copy only symbol @var{symbolname} from the source file. This option may
910 be given more than once.
912 @item -N @var{symbolname}
913 @itemx --strip-symbol=@var{symbolname}
914 Do not copy symbol @var{symbolname} from the source file. This option
915 may be given more than once.
917 @item -L @var{symbolname}
918 @itemx --localize-symbol=@var{symbolname}
919 Make symbol @var{symbolname} local to the file, so that it is not
920 visible externally. This option may be given more than once.
922 @item -W @var{symbolname}
923 @itemx --weaken-symbol=@var{symbolname}
924 Make symbol @var{symbolname} weak. This option may be given more than once.
928 Do not copy non-global symbols from the source file.
929 @c FIXME any reason to prefer "non-global" to "local" here?
932 @itemx --discard-locals
933 Do not copy compiler-generated local symbols.
934 (These usually start with @samp{L} or @samp{.}.)
937 @itemx --byte=@var{byte}
938 Keep only every @var{byte}th byte of the input file (header data is not
939 affected). @var{byte} can be in the range from 0 to @var{interleave}-1,
940 where @var{interleave} is given by the @samp{-i} or @samp{--interleave}
941 option, or the default of 4. This option is useful for creating files
942 to program @sc{rom}. It is typically used with an @code{srec} output
945 @item -i @var{interleave}
946 @itemx --interleave=@var{interleave}
947 Only copy one out of every @var{interleave} bytes. Select which byte to
948 copy with the @var{-b} or @samp{--byte} option. The default is 4.
949 @code{objcopy} ignores this option if you do not specify either @samp{-b} or
953 @itemx --preserve-dates
954 Set the access and modification dates of the output file to be the same
955 as those of the input file.
958 Convert debugging information, if possible. This is not the default
959 because only certain debugging formats are supported, and the
960 conversion process can be time consuming.
962 @item --gap-fill @var{val}
963 Fill gaps between sections with @var{val}. This operation applies to
964 the @emph{load address} (LMA) of the sections. It is done by increasing
965 the size of the section with the lower address, and filling in the extra
966 space created with @var{val}.
968 @item --pad-to @var{address}
969 Pad the output file up to the load address @var{address}. This is
970 done by increasing the size of the last section. The extra space is
971 filled in with the value specified by @samp{--gap-fill} (default zero).
973 @item --set-start @var{val}
974 Set the address of the new file to @var{val}. Not all object file
975 formats support setting the start address.
977 @item --adjust-start @var{incr}
978 Adjust the start address by adding @var{incr}. Not all object file
979 formats support setting the start address.
981 @item --adjust-vma @var{incr}
982 Adjust the address of all sections, as well as the start address, by
983 adding @var{incr}. Some object file formats do not permit section
984 addresses to be changed arbitrarily. Note that this does not relocate
985 the sections; if the program expects sections to be loaded at a certain
986 address, and this option is used to change the sections such that they
987 are loaded at a different address, the program may fail.
989 @item --adjust-section-vma @var{section}@{=,+,-@}@var{val}
990 Set or adjust the address of the named @var{section}. If @samp{=} is
991 used, the section address is set to @var{val}. Otherwise, @var{val} is
992 added to or subtracted from the section address. See the comments under
993 @samp{--adjust-vma}, above. If @var{section} does not exist in the
994 input file, a warning will be issued, unless @samp{--no-adjust-warnings}
997 @item --adjust-warnings
998 If @samp{--adjust-section-vma} is used, and the named section does not
999 exist, issue a warning. This is the default.
1001 @item --no-adjust-warnings
1002 Do not issue a warning if @samp{--adjust-section-vma} is used, even if
1003 the named section does not exist.
1005 @item --set-section-flags @var{section}=@var{flags}
1006 Set the flags for the named section. The @var{flags} argument is a
1007 comma separated string of flag names. The recognized names are
1008 @samp{alloc}, @samp{contents}, @samp{load}, @samp{readonly},
1009 @samp{code}, @samp{data}, and @samp{rom}. You can set the
1010 @samp{contents} flag for a section which does not have contents, but it
1011 is not meaningful to clear the @samp{contents} flag of a section which
1012 does have contents--just remove the section instead. Not all flags are
1013 meaningful for all object file formats.
1015 @item --add-section @var{sectionname}=@var{filename}
1016 Add a new section named @var{sectionname} while copying the file. The
1017 contents of the new section are taken from the file @var{filename}. The
1018 size of the section will be the size of the file. This option only
1019 works on file formats which can support sections with arbitrary names.
1021 @item --change-leading-char
1022 Some object file formats use special characters at the start of
1023 symbols. The most common such character is underscore, which compilers
1024 often add before every symbol. This option tells @code{objcopy} to
1025 change the leading character of every symbol when it converts between
1026 object file formats. If the object file formats use the same leading
1027 character, this option has no effect. Otherwise, it will add a
1028 character, or remove a character, or change a character, as
1031 @item --remove-leading-char
1032 If the first character of a global symbol is a special symbol leading
1033 character used by the object file format, remove the character. The
1034 most common symbol leading character is underscore. This option will
1035 remove a leading underscore from all global symbols. This can be useful
1036 if you want to link together objects of different file formats with
1037 different conventions for symbol names. This is different from
1038 @code{--change-leading-char} because it always changes the symbol name
1039 when appropriate, regardless of the object file format of the output
1043 Change all global symbols in the file to be weak. This can be useful
1044 when building an object which will be linked against other objects using
1045 the @code{-R} option to the linker. This option is only effective when
1046 using an object file format which supports weak symbols.
1050 Show the version number of @code{objcopy}.
1054 Verbose output: list all object files modified. In the case of
1055 archives, @samp{objcopy -V} lists all members of the archive.
1058 Show a summary of the options to @code{objcopy}.
1064 @cindex object file information
1068 objdump [ -a | --archive-headers ]
1069 [ -b @var{bfdname} | --target=@var{bfdname} ] [ --debugging ]
1070 [ -C | --demangle ] [ -d | --disassemble ]
1071 [ -D | --disassemble-all ] [ --disassemble-zeroes ]
1072 [ -EB | -EL | --endian=@{big | little @} ]
1073 [ -f | --file-headers ]
1074 [ -h | --section-headers | --headers ] [ -i | --info ]
1075 [ -j @var{section} | --section=@var{section} ]
1076 [ -l | --line-numbers ] [ -S | --source ]
1077 [ -m @var{machine} | --architecture=@var{machine} ]
1078 [ -r | --reloc ] [ -R | --dynamic-reloc ]
1079 [ -s | --full-contents ] [ --stabs ]
1080 [ -t | --syms ] [ -T | --dynamic-syms ] [ -x | --all-headers ]
1081 [ -w | --wide ] [ --start-address=@var{address} ]
1082 [ --stop-address=@var{address} ]
1083 [ --prefix-addresses] [ --[no-]show-raw-insn ]
1084 [ --adjust-vma=@var{offset} ]
1085 [ --version ] [ --help ]
1086 @var{objfile}@dots{}
1089 @code{objdump} displays information about one or more object files.
1090 The options control what particular information to display. This
1091 information is mostly useful to programmers who are working on the
1092 compilation tools, as opposed to programmers who just want their
1093 program to compile and work.
1095 @var{objfile}@dots{} are the object files to be examined. When you
1096 specify archives, @code{objdump} shows information on each of the member
1099 The long and short forms of options, shown here as alternatives, are
1100 equivalent. At least one option besides @samp{-l} must be given.
1104 @itemx --archive-header
1105 @cindex archive headers
1106 If any of the @var{objfile} files are archives, display the archive
1107 header information (in a format similar to @samp{ls -l}). Besides the
1108 information you could list with @samp{ar tv}, @samp{objdump -a} shows
1109 the object file format of each archive member.
1111 @item --adjust-vma=@var{offset}
1112 @cindex section addresses in objdump
1113 @cindex VMA in objdump
1114 When dumping information, first add @var{offset} to all the section
1115 addresses. This is useful if the section addresses do not correspond to
1116 the symbol table, which can happen when putting sections at particular
1117 addresses when using a format which can not represent section addresses,
1120 @item -b @var{bfdname}
1121 @itemx --target=@var{bfdname}
1122 @cindex object code format
1123 Specify that the object-code format for the object files is
1124 @var{bfdname}. This option may not be necessary; @var{objdump} can
1125 automatically recognize many formats.
1129 objdump -b oasys -m vax -h fu.o
1132 displays summary information from the section headers (@samp{-h}) of
1133 @file{fu.o}, which is explicitly identified (@samp{-m}) as a VAX object
1134 file in the format produced by Oasys compilers. You can list the
1135 formats available with the @samp{-i} option.
1136 @xref{Target Selection}, for more information.
1140 @cindex demangling in objdump
1141 Decode (@dfn{demangle}) low-level symbol names into user-level names.
1142 Besides removing any initial underscore prepended by the system, this
1143 makes C++ function names readable. @xref{c++filt}, for more information
1147 Display debugging information. This attempts to parse debugging
1148 information stored in the file and print it out using a C like syntax.
1149 Only certain types of debugging information have been implemented.
1152 @itemx --disassemble
1153 @cindex disassembling object code
1154 @cindex machine instructions
1155 Display the assembler mnemonics for the machine instructions from
1156 @var{objfile}. This option only disassembles those sections which are
1157 expected to contain instructions.
1160 @itemx --disassemble-all
1161 Like @samp{-d}, but disassemble the contents of all sections, not just
1162 those expected to contain instructions.
1164 @item --prefix-addresses
1165 When disassembling, print the complete address on each line. This is
1166 the older disassembly format.
1168 @item --disassemble-zeroes
1169 Normally the disassembly output will skip blocks of zeroes. This
1170 option directs the disassembler to disassemble those blocks, just like
1175 @itemx --endian=@{big|little@}
1177 @cindex disassembly endianness
1178 Specify the endianness of the object files. This only affects
1179 disassembly. This can be useful when disassembling a file format which
1180 does not describe endianness information, such as S-records.
1183 @itemx --file-header
1184 @cindex object file header
1185 Display summary information from the overall header of
1186 each of the @var{objfile} files.
1189 @itemx --section-header
1191 @cindex section headers
1192 Display summary information from the section headers of the
1195 File segments may be relocated to nonstandard addresses, for example by
1196 using the @samp{-Ttext}, @samp{-Tdata}, or @samp{-Tbss} options to
1197 @code{ld}. However, some object file formats, such as a.out, do not
1198 store the starting address of the file segments. In those situations,
1199 although @code{ld} relocates the sections correctly, using @samp{objdump
1200 -h} to list the file section headers cannot show the correct addresses.
1201 Instead, it shows the usual addresses, which are implicit for the
1205 Print a summary of the options to @code{objdump} and exit.
1209 @cindex architectures available
1210 @cindex object formats available
1211 Display a list showing all architectures and object formats available
1212 for specification with @samp{-b} or @samp{-m}.
1215 @itemx --section=@var{name}
1216 @cindex section information
1217 Display information only for section @var{name}.
1220 @itemx --line-numbers
1221 @cindex source filenames for object files
1222 Label the display (using debugging information) with the filename and
1223 source line numbers corresponding to the object code or relocs shown.
1224 Only useful with @samp{-d}, @samp{-D}, or @samp{-r}.
1226 @item -m @var{machine}
1227 @itemx --architecture=@var{machine}
1228 @cindex architecture
1229 @cindex disassembly architecture
1230 Specify the architecture to use when disassembling object files. This
1231 can be useful when disasembling object files which do not describe
1232 architecture information, such as S-records. You can list the available
1233 architectures with the @samp{-i} option.
1237 @cindex relocation entries, in object file
1238 Print the relocation entries of the file. If used with @samp{-d} or
1239 @samp{-D}, the relocations are printed interspersed with the
1243 @itemx --dynamic-reloc
1244 @cindex dynamic relocation entries, in object file
1245 Print the dynamic relocation entries of the file. This is only
1246 meaningful for dynamic objects, such as certain types of shared
1250 @itemx --full-contents
1251 @cindex sections, full contents
1252 @cindex object file sections
1253 Display the full contents of any sections requested.
1257 @cindex source disassembly
1258 @cindex disassembly, with source
1259 Display source code intermixed with disassembly, if possible. Implies
1262 @item --show-raw-insn
1263 When disassembling instructions, print the instruction in hex as well as
1264 in symbolic form. This is the default except when
1265 @code{--prefix-addresses} is used.
1267 @item --no-show-raw-insn
1268 When disassembling instructions, do not print the instruction bytes.
1269 This is the default when @code{--prefix-addresses} is used.
1274 @cindex debug symbols
1275 @cindex ELF object file format
1276 Display the full contents of any sections requested. Display the
1277 contents of the .stab and .stab.index and .stab.excl sections from an
1278 ELF file. This is only useful on systems (such as Solaris 2.0) in which
1279 @code{.stab} debugging symbol-table entries are carried in an ELF
1280 section. In most other file formats, debugging symbol-table entries are
1281 interleaved with linkage symbols, and are visible in the @samp{--syms}
1282 output. For more information on stabs symbols, see @ref{Top,Stabs,Stabs
1283 Overview,stabs.info, The ``stabs'' debug format}.
1285 @item --start-address=@var{address}
1286 @cindex start-address
1287 Start displaying data at the specified address. This affects the output
1288 of the @code{-d}, @code{-r} and @code{-s} options.
1290 @item --stop-address=@var{address}
1291 @cindex stop-address
1292 Stop displaying data at the specified address. This affects the output
1293 of the @code{-d}, @code{-r} and @code{-s} options.
1297 @cindex symbol table entries, printing
1298 Print the symbol table entries of the file.
1299 This is similar to the information provided by the @samp{nm} program.
1302 @itemx --dynamic-syms
1303 @cindex dynamic symbol table entries, printing
1304 Print the dynamic symbol table entries of the file. This is only
1305 meaningful for dynamic objects, such as certain types of shared
1306 libraries. This is similar to the information provided by the @samp{nm}
1307 program when given the @samp{-D} (@samp{--dynamic}) option.
1310 Print the version number of @code{objdump} and exit.
1314 @cindex all header information, object file
1315 @cindex header information, all
1316 Display all available header information, including the symbol table and
1317 relocation entries. Using @samp{-x} is equivalent to specifying all of
1318 @samp{-a -f -h -r -t}.
1322 @cindex wide output, printing
1323 Format some lines for output devices that have more than 80 columns.
1330 @cindex archive contents
1331 @cindex symbol index
1334 ranlib [-vV] @var{archive}
1337 @code{ranlib} generates an index to the contents of an archive and
1338 stores it in the archive. The index lists each symbol defined by a
1339 member of an archive that is a relocatable object file.
1341 You may use @samp{nm -s} or @samp{nm --print-armap} to list this index.
1343 An archive with such an index speeds up linking to the library and
1344 allows routines in the library to call each other without regard to
1345 their placement in the archive.
1347 The @sc{gnu} @code{ranlib} program is another form of @sc{gnu} @code{ar}; running
1348 @code{ranlib} is completely equivalent to executing @samp{ar -s}.
1354 Show the version number of @code{ranlib}.
1361 @cindex section sizes
1364 size [ -A | -B | --format=@var{compatibility} ]
1365 [ --help ] [ -d | -o | -x | --radix=@var{number} ]
1366 [ --target=@var{bfdname} ] [ -V | --version ]
1367 [ @var{objfile}@dots{} ]
1370 The @sc{gnu} @code{size} utility lists the section sizes---and the total
1371 size---for each of the object or archive files @var{objfile} in its
1372 argument list. By default, one line of output is generated for each
1373 object file or each module in an archive.
1375 @var{objfile}@dots{} are the object files to be examined.
1376 If none are specified, the file @code{a.out} will be used.
1378 The command line options have the following meanings:
1383 @itemx --format=@var{compatibility}
1384 @cindex @code{size} display format
1385 Using one of these options, you can choose whether the output from @sc{gnu}
1386 @code{size} resembles output from System V @code{size} (using @samp{-A},
1387 or @samp{--format=sysv}), or Berkeley @code{size} (using @samp{-B}, or
1388 @samp{--format=berkeley}). The default is the one-line format similar to
1390 @c Bonus for doc-source readers: you can also say --format=strange (or
1391 @c anything else that starts with 's') for sysv, and --format=boring (or
1392 @c anything else that starts with 'b') for Berkeley.
1394 Here is an example of the Berkeley (default) format of output from
1397 size --format=Berkeley ranlib size
1398 text data bss dec hex filename
1399 294880 81920 11592 388392 5ed28 ranlib
1400 294880 81920 11888 388688 5ee50 size
1404 This is the same data, but displayed closer to System V conventions:
1407 size --format=SysV ranlib size
1425 Show a summary of acceptable arguments and options.
1430 @itemx --radix=@var{number}
1431 @cindex @code{size} number format
1432 @cindex radix for section sizes
1433 Using one of these options, you can control whether the size of each
1434 section is given in decimal (@samp{-d}, or @samp{--radix=10}); octal
1435 (@samp{-o}, or @samp{--radix=8}); or hexadecimal (@samp{-x}, or
1436 @samp{--radix=16}). In @samp{--radix=@var{number}}, only the three
1437 values (8, 10, 16) are supported. The total size is always given in two
1438 radices; decimal and hexadecimal for @samp{-d} or @samp{-x} output, or
1439 octal and hexadecimal if you're using @samp{-o}.
1441 @item --target=@var{bfdname}
1442 @cindex object code format
1443 Specify that the object-code format for @var{objfile} is
1444 @var{bfdname}. This option may not be necessary; @code{size} can
1445 automatically recognize many formats.
1446 @xref{Target Selection}, for more information.
1450 Display the version number of @code{size}.
1456 @cindex listings strings
1457 @cindex printing strings
1458 @cindex strings, printing
1461 strings [-afov] [-@var{min-len}] [-n @var{min-len}] [-t @var{radix}] [-]
1462 [--all] [--print-file-name] [--bytes=@var{min-len}]
1463 [--radix=@var{radix}] [--target=@var{bfdname}]
1464 [--help] [--version] @var{file}@dots{}
1467 For each @var{file} given, @sc{gnu} @code{strings} prints the printable
1468 character sequences that are at least 4 characters long (or the number
1469 given with the options below) and are followed by an unprintable
1470 character. By default, it only prints the strings from the initialized
1471 and loaded sections of object files; for other types of files, it prints
1472 the strings from the whole file.
1474 @code{strings} is mainly useful for determining the contents of non-text
1481 Do not scan only the initialized and loaded sections of object files;
1482 scan the whole files.
1485 @itemx --print-file-name
1486 Print the name of the file before each string.
1489 Print a summary of the program usage on the standard output and exit.
1491 @itemx -@var{min-len}
1492 @item -n @var{min-len}
1493 @itemx --bytes=@var{min-len}
1494 Print sequences of characters that are at least @var{min-len} characters
1495 long, instead of the default 4.
1498 Like @samp{-t o}. Some other versions of @code{strings} have @samp{-o}
1499 act like @samp{-t d} instead. Since we can not be compatible with both
1500 ways, we simply chose one.
1502 @item -t @var{radix}
1503 @itemx --radix=@var{radix}
1504 Print the offset within the file before each string. The single
1505 character argument specifies the radix of the offset---@samp{o} for
1506 octal, @samp{x} for hexadecimal, or @samp{d} for decimal.
1508 @item --target=@var{bfdname}
1509 @cindex object code format
1510 Specify an object code format other than your system's default format.
1511 @xref{Target Selection}, for more information.
1515 Print the program version number on the standard output and exit.
1522 @cindex removing symbols
1523 @cindex discarding symbols
1524 @cindex symbols, discarding
1527 strip [ -F @var{bfdname} | --target=@var{bfdname} ]
1528 [ -I @var{bfdname} | --input-target=@var{bfdname} ]
1529 [ -O @var{bfdname} | --output-target=@var{bfdname} ]
1530 [ -s | --strip-all ] [ -S | -g | --strip-debug ]
1531 [ -K @var{symbolname} | --keep-symbol=@var{symbolname} ]
1532 [ -N @var{symbolname} | --strip-symbol=@var{symbolname} ]
1533 [ -x | --discard-all ] [ -X | --discard-locals ]
1534 [ -R @var{sectionname} | --remove-section=@var{sectionname} ]
1535 [ -o @var{file} ] [ -p | --preserve-dates ]
1536 [ -v | --verbose ] [ -V | --version ] [ --help ]
1537 @var{objfile}@dots{}
1540 @sc{gnu} @code{strip} discards all symbols from object files
1541 @var{objfile}. The list of object files may include archives.
1542 At least one object file must be given.
1544 @code{strip} modifies the files named in its argument,
1545 rather than writing modified copies under different names.
1548 @item -F @var{bfdname}
1549 @itemx --target=@var{bfdname}
1550 Treat the original @var{objfile} as a file with the object
1551 code format @var{bfdname}, and rewrite it in the same format.
1552 @xref{Target Selection}, for more information.
1555 Show a summary of the options to @code{strip} and exit.
1557 @item -I @var{bfdname}
1558 @itemx --input-target=@var{bfdname}
1559 Treat the original @var{objfile} as a file with the object
1560 code format @var{bfdname}.
1561 @xref{Target Selection}, for more information.
1563 @item -O @var{bfdname}
1564 @itemx --output-target=@var{bfdname}
1565 Replace @var{objfile} with a file in the output format @var{bfdname}.
1566 @xref{Target Selection}, for more information.
1568 @item -R @var{sectionname}
1569 @itemx --remove-section=@var{sectionname}
1570 Remove any section named @var{sectionname} from the output file. This
1571 option may be given more than once. Note that using this option
1572 inappropriately may make the output file unusable.
1580 @itemx --strip-debug
1581 Remove debugging symbols only.
1583 @item --strip-unneeded
1584 Remove all symbols that are not needed for relocation processing.
1586 @item -K @var{symbolname}
1587 @itemx --keep-symbol=@var{symbolname}
1588 Keep only symbol @var{symbolname} from the source file. This option may
1589 be given more than once.
1591 @item -N @var{symbolname}
1592 @itemx --strip-symbol=@var{symbolname}
1593 Remove symbol @var{symbolname} from the source file. This option may be
1594 given more than once, and may be combined with strip options other than
1598 Put the stripped output in @var{file}, rather than replacing the
1599 existing file. When this argument is used, only one @var{objfile}
1600 argument may be specified.
1603 @itemx --preserve-dates
1604 Preserve the access and modification dates of the file.
1607 @itemx --discard-all
1608 Remove non-global symbols.
1611 @itemx --discard-locals
1612 Remove compiler-generated local symbols.
1613 (These usually start with @samp{L} or @samp{.}.)
1617 Show the version number for @code{strip}.
1621 Verbose output: list all object files modified. In the case of
1622 archives, @samp{strip -v} lists all members of the archive.
1629 @cindex demangling C++ symbols
1632 c++filt [ -_ | --strip-underscores ]
1633 [ -n | --no-strip-underscores ]
1634 [ -s @var{format} | --format=@var{format} ]
1635 [ --help ] [ --version ] [ @var{symbol}@dots{} ]
1638 The C++ language provides function overloading, which means that you can
1639 write many functions with the same name (providing each takes parameters
1640 of different types). All C++ function names are encoded into a
1641 low-level assembly label (this process is known as
1642 @dfn{mangling}). The @code{c++filt} program does the inverse mapping: it
1643 decodes (@dfn{demangles}) low-level names into user-level names so that
1644 the linker can keep these overloaded functions from clashing.
1646 Every alphanumeric word (consisting of letters, digits, underscores,
1647 dollars, or periods) seen in the input is a potential label. If the
1648 label decodes into a C++ name, the C++ name replaces the low-level
1651 You can use @code{c++filt} to decipher individual symbols:
1654 c++filt @var{symbol}
1657 If no @var{symbol} arguments are given, @code{c++filt} reads symbol
1658 names from the standard input and writes the demangled names to the
1659 standard output. All results are printed on the standard output.
1663 @itemx --strip-underscores
1664 On some systems, both the C and C++ compilers put an underscore in front
1665 of every name. For example, the C name @code{foo} gets the low-level
1666 name @code{_foo}. This option removes the initial underscore. Whether
1667 @code{c++filt} removes the underscore by default is target dependent.
1670 @itemx --no-strip-underscores
1671 Do not remove the initial underscore.
1673 @item -s @var{format}
1674 @itemx --format=@var{format}
1675 @sc{gnu} @code{nm} can decode three different methods of mangling, used by
1676 different C++ compilers. The argument to this option selects which
1681 the one used by the @sc{gnu} compiler (the default method)
1683 the one used by the Lucid compiler
1685 the one specified by the C++ Annotated Reference Manual
1689 Print a summary of the options to @code{c++filt} and exit.
1692 Print the version number of @code{c++filt} and exit.
1696 @emph{Warning:} @code{c++filt} is a new utility, and the details of its
1697 user interface are subject to change in future releases. In particular,
1698 a command-line option may be required in the the future to decode a name
1699 passed as an argument on the command line; in other words,
1702 c++filt @var{symbol}
1706 may in a future release become
1709 c++filt @var{option} @var{symbol}
1717 @cindex address to file name and line number
1720 addr2line [ -b @var{bfdname} | --target=@var{bfdname} ]
1722 [ -e @var{filename} | --exe=@var{filename} ]
1723 [ -f | --functions ] [ -s | --basename ]
1724 [ -H | --help ] [ -V | --version ]
1728 @code{addr2line} translates program addresses into file names and line
1729 numbers. Given an address and an executable, it uses the debugging
1730 information in the executable to figure out which file name and line
1731 number are associated with a given address.
1733 The executable to use is specified with the @code{-e} option. The
1734 default is @file{a.out}.
1736 @code{addr2line} has two modes of operation.
1738 In the first, hexadecimal addresses are specified on the command line,
1739 and @code{addr2line} displays the file name and line number for each
1742 In the second, @code{addr2line} reads hexadecimal addresses from
1743 standard input, and prints the file name and line number for each
1744 address on standard output. In this mode, @code{addr2line} may be used
1745 in a pipe to convert dynamically chosen addresses.
1747 The format of the output is @samp{FILENAME:LINENO}. The file name and
1748 line number for each address is printed on a separate line. If the
1749 @code{-f} option is used, then each @samp{FILENAME:LINENO} line is
1750 preceded by a @samp{FUNCTIONNAME} line which is the name of the function
1751 containing the address.
1753 If the file name or function name can not be determined,
1754 @code{addr2line} will print two question marks in their place. If the
1755 line number can not be determined, @code{addr2line} will print 0.
1757 The long and short forms of options, shown here as alternatives, are
1761 @item -b @var{bfdname}
1762 @itemx --target=@var{bfdname}
1763 @cindex object code format
1764 Specify that the object-code format for the object files is
1769 @cindex demangling in objdump
1770 Decode (@dfn{demangle}) low-level symbol names into user-level names.
1771 Besides removing any initial underscore prepended by the system, this
1772 makes C++ function names readable. @xref{c++filt}, for more information
1775 @item -e @var{filename}
1776 @itemx --exe=@var{filename}
1777 Specify the name of the executable for which addresses should be
1778 translated. The default file is @file{a.out}.
1782 Display function names as well as file and line number information.
1786 Display only the base of each file name.
1792 @code{nlmconv} converts a relocatable object file into a NetWare
1796 @code{nlmconv} currently works with @samp{i386} object
1797 files in @code{coff}, @sc{elf}, or @code{a.out} format, and @sc{SPARC}
1798 object files in @sc{elf}, or @code{a.out} format@footnote{
1799 @code{nlmconv} should work with any @samp{i386} or @sc{sparc} object
1800 format in the Binary File Descriptor library. It has only been tested
1801 with the above formats.}.
1805 @emph{Warning:} @code{nlmconv} is not always built as part of the binary
1806 utilities, since it is only useful for NLM targets.
1810 nlmconv [ -I @var{bfdname} | --input-target=@var{bfdname} ]
1811 [ -O @var{bfdname} | --output-target=@var{bfdname} ]
1812 [ -T @var{headerfile} | --header-file=@var{headerfile} ]
1813 [ -d | --debug] [ -l @var{linker} | --linker=@var{linker} ]
1814 [ -h | --help ] [ -V | --version ]
1815 @var{infile} @var{outfile}
1818 @code{nlmconv} converts the relocatable @samp{i386} object file
1819 @var{infile} into the NetWare Loadable Module @var{outfile}, optionally
1820 reading @var{headerfile} for NLM header information. For instructions
1821 on writing the NLM command file language used in header files, see the
1822 @samp{linkers} section, @samp{NLMLINK} in particular, of the @cite{NLM
1823 Development and Tools Overview}, which is part of the NLM Software
1824 Developer's Kit (``NLM SDK''), available from Novell, Inc.
1825 @code{nlmconv} uses the @sc{gnu} Binary File Descriptor library to read
1826 @var{infile}; see @ref{BFD,,BFD,ld.info,Using LD}, for
1829 @code{nlmconv} can perform a link step. In other words, you can list
1830 more than one object file for input if you list them in the definitions
1831 file (rather than simply specifying one input file on the command line).
1832 In this case, @code{nlmconv} calls the linker for you.
1835 @item -I @var{bfdname}
1836 @itemx --input-target=@var{bfdname}
1837 Object format of the input file. @code{nlmconv} can usually determine
1838 the format of a given file (so no default is necessary).
1839 @xref{Target Selection}, for more information.
1841 @item -O @var{bfdname}
1842 @itemx --output-target=@var{bfdname}
1843 Object format of the output file. @code{nlmconv} infers the output
1844 format based on the input format, e.g. for a @samp{i386} input file the
1845 output format is @samp{nlm32-i386}.
1846 @xref{Target Selection}, for more information.
1848 @item -T @var{headerfile}
1849 @itemx --header-file=@var{headerfile}
1850 Reads @var{headerfile} for NLM header information. For instructions on
1851 writing the NLM command file language used in header files, see@ see the
1852 @samp{linkers} section, of the @cite{NLM Development and Tools
1853 Overview}, which is part of the NLM Software Developer's Kit, available
1858 Displays (on standard error) the linker command line used by @code{nlmconv}.
1860 @item -l @var{linker}
1861 @itemx --linker=@var{linker}
1862 Use @var{linker} for any linking. @var{linker} can be an abosolute or a
1867 Prints a usage summary.
1871 Prints the version number for @code{nlmconv}.
1877 @code{windres} may be used to manipulate Windows resources.
1880 @emph{Warning:} @code{windres} is not always built as part of the binary
1881 utilities, since it is only useful for Windows targets.
1885 windres [options] [input-file] [output-file]
1888 @code{windres} reads resources from an input file and copies them into
1889 an output file. Either file may be in one of three formats:
1893 A text format read by the Resource Compiler.
1896 A binary format generated by the Resource Compiler.
1899 A COFF object or executable.
1902 The exact description of these different formats is available in
1903 documentation from Microsoft.
1905 When @code{windres} converts from the @code{rc} format to the @code{res}
1906 format, it is acting like the Windows Resource Compiler. When
1907 @code{windres} converts from the @code{res} format to the @code{coff}
1908 format, it is acting like the Windows @code{CVTRES} program.
1910 When @code{windres} generates an @code{rc} file, the output is similar
1911 but not identical to the format expected for the input. When an input
1912 @code{rc} file refers to an external filename, an output @code{rc} file
1913 will instead include the file contents.
1915 If the input or output format is not specified, @code{windres} will
1916 guess based on the file name, or, for the input file, the file contents.
1917 A file with an extension of @file{.rc} will be treated as an @code{rc}
1918 file, a file with an extension of @file{.res} will be treated as a
1919 @code{res} file, and a file with an extension of @file{.o} or
1920 @file{.exe} will be treated as a @code{coff} file.
1922 If no output file is specified, @code{windres} will print the resources
1923 in @code{rc} format to standard output.
1925 The normal use is for you to write an @code{rc} file, use @code{windres}
1926 to convert it to a COFF object file, and then link the COFF file into
1927 your application. This will make the resources described in the
1928 @code{rc} file available to Windows.
1931 @item -i @var{filename}
1932 @itemx --input @var{filename}
1933 The name of the input file. If this option is not used, then
1934 @code{windres} will use the first non-option argument as the input file
1935 name. If there are no non-option arguments, then @code{windres} will
1936 read from standard input. @code{windres} can not read a COFF file from
1939 @item -o @var{filename}
1940 @itemx --output @var{filename}
1941 The name of the output file. If this option is not used, then
1942 @code{windres} will use the first non-option argument, after any used
1943 for the input file name, as the output file name. If there is no
1944 non-option argument, then @code{windres} will write to standard output.
1945 @code{windres} can not write a COFF file to standard output.
1947 @item -I @var{format}
1948 @itemx --input-format @var{format}
1949 The input format to read. @var{format} may be @samp{res}, @samp{rc}, or
1950 @samp{coff}. If no input format is specified, @code{windres} will
1951 guess, as described above.
1953 @item -O @var{format}
1954 @itemx --output-format @var{format}
1955 The output format to generate. @var{format} may be @samp{res},
1956 @samp{rc}, or @samp{coff}. If no output format is specified,
1957 @code{windres} will guess, as described above.
1959 @item -F @var{target}
1960 @itemx --target @var{target}
1961 Specify the BFD format to use for a COFF file as input or output. This
1962 is a BFD target name; you can use the @code{--help} option to see a list
1963 of supported targets. Normally @code{windres} will use the default
1964 format, which is the first one listed by the @code{--help} option.
1965 @ref{Target Selection}.
1967 @item --preprocessor @var{program}
1968 When @code{windres} reads an @code{rc} file, it runs it through the C
1969 preprocessor first. This option may be used to specify the preprocessor
1970 to use, including any leading arguments. The default preprocessor
1971 argument is @code{gcc -E -xc-header -DRC_INVOKED}.
1973 @item --include-dir @var{directory}
1974 Specify an include directory to use when reading an @code{rc} file.
1975 @code{windres} will pass this to the preprocessor as an @code{-I}
1976 option. @code{windres} will also search this directory when looking for
1977 files named in the @code{rc} file.
1979 @item --define @var{sym[=val]}
1980 Specify a @code{-D} option to pass to the preprocessor when reading an
1983 @item --language @var{val}
1984 Specify the default language to use when reading an @code{rc} file.
1985 @var{val} should be a hexadecimal language code. The low eight bits are
1986 the language, and the high eight bits are the sublanguage.
1989 Prints a usage summary.
1992 Prints the version number for @code{windres}.
1995 If @code{windres} is compiled with @code{YYDEBUG} defined as @code{1},
1996 this will turn on parser debugging.
1999 @node Selecting The Target System
2000 @chapter Selecting the target system
2002 You can specify three aspects of the target system to the @sc{gnu}
2003 binary file utilities, each in several ways:
2013 the linker emulation (which applies to the linker only)
2016 In the following summaries, the lists of ways to specify values are in
2017 order of decreasing precedence. The ways listed first override those
2020 The commands to list valid values only list the values for which the
2021 programs you are running were configured. If they were configured with
2022 @samp{--enable-targets=all}, the commands list most of the available
2023 values, but a few are left out; not all targets can be configured in at
2024 once because some of them can only be configured @dfn{native} (on hosts
2025 with the same type as the target system).
2028 * Target Selection::
2029 * Architecture Selection::
2030 * Linker Emulation Selection::
2033 @node Target Selection
2034 @section Target Selection
2036 A @dfn{target} is an object file format. A given target may be
2037 supported for multiple architectures (@pxref{Architecture Selection}).
2038 A target selection may also have variations for different operating
2039 systems or architectures.
2041 The command to list valid target values is @samp{objdump -i}
2042 (the first column of output contains the relevant information).
2044 Some sample values are: @samp{a.out-hp300bsd}, @samp{ecoff-littlemips},
2045 @samp{a.out-sunos-big}.
2047 You can also specify a target using a configuration triplet. This is
2048 the same sort of name that is passed to configure to specify a target.
2049 When you use a configuration triplet as an argument, it must be fully
2050 canonicalized. You can see the canonical version of a triplet by
2051 running the shell script @file{config.sub} which is included with the
2054 Some sample configuration triplets are: @samp{m68k-hp-bsd},
2055 @samp{mips-dec-ultrix}, @samp{sparc-sun-sunos}.
2057 @subheading @code{objdump} Target
2063 command line option: @samp{-b} or @samp{--target}
2066 environment variable @code{GNUTARGET}
2069 deduced from the input file
2072 @subheading @code{objcopy} and @code{strip} Input Target
2078 command line options: @samp{-I} or @samp{--input-target}, or @samp{-F} or @samp{--target}
2081 environment variable @code{GNUTARGET}
2084 deduced from the input file
2087 @subheading @code{objcopy} and @code{strip} Output Target
2093 command line options: @samp{-O} or @samp{--output-target}, or @samp{-F} or @samp{--target}
2096 the input target (see ``@code{objcopy} and @code{strip} Input Target'' above)
2099 environment variable @code{GNUTARGET}
2102 deduced from the input file
2105 @subheading @code{nm}, @code{size}, and @code{strings} Target
2111 command line option: @samp{--target}
2114 environment variable @code{GNUTARGET}
2117 deduced from the input file
2120 @subheading Linker Input Target
2126 command line option: @samp{-b} or @samp{--format}
2127 (@pxref{Options,,Options,ld.info,Using LD})
2130 script command @code{TARGET}
2131 (@pxref{Option Commands,,Option Commands,ld.info,Using LD})
2134 environment variable @code{GNUTARGET}
2135 (@pxref{Environment,,Environment,ld.info,Using LD})
2138 the default target of the selected linker emulation
2139 (@pxref{Linker Emulation Selection})
2142 @subheading Linker Output Target
2148 command line option: @samp{-oformat}
2149 (@pxref{Options,,Options,ld.info,Using LD})
2152 script command @code{OUTPUT_FORMAT}
2153 (@pxref{Option Commands,,Option Commands,ld.info,Using LD})
2156 the linker input target (see ``Linker Input Target'' above)
2159 @node Architecture Selection
2160 @section Architecture selection
2162 An @dfn{architecture} is a type of @sc{cpu} on which an object file is
2163 to run. Its name may contain a colon, separating the name of the
2164 processor family from the name of the particular @sc{cpu}.
2166 The command to list valid architecture values is @samp{objdump -i} (the
2167 second column contains the relevant information).
2169 Sample values: @samp{m68k:68020}, @samp{mips:3000}, @samp{sparc}.
2171 @subheading @code{objdump} Architecture
2177 command line option: @samp{-m} or @samp{--architecture}
2180 deduced from the input file
2183 @subheading @code{objcopy}, @code{nm}, @code{size}, @code{strings} Architecture
2189 deduced from the input file
2192 @subheading Linker Input Architecture
2198 deduced from the input file
2201 @subheading Linker Output Architecture
2207 script command @code{OUTPUT_ARCH}
2208 (@pxref{Option Commands,,Option Commands,ld.info,Using LD})
2211 the default architecture from the linker output target
2212 (@pxref{Target Selection})
2215 @node Linker Emulation Selection
2216 @section Linker emulation selection
2218 A linker @dfn{emulation} is a ``personality'' of the linker, which gives
2219 the linker default values for the other aspects of the target system.
2220 In particular, it consists of
2230 several ``hook'' functions that are run at certain stages of the linking
2231 process to do special things that some targets require
2234 The command to list valid linker emulation values is @samp{ld -V}.
2236 Sample values: @samp{hp300bsd}, @samp{mipslit}, @samp{sun4}.
2242 command line option: @samp{-m}
2243 (@pxref{Options,,Options,ld.info,Using LD})
2246 environment variable @code{LDEMULATION}
2249 compiled-in @code{DEFAULT_EMULATION} from @file{Makefile},
2250 which comes from @code{EMUL} in @file{config/@var{target}.mt}
2253 @node Reporting Bugs
2254 @chapter Reporting Bugs
2256 @cindex reporting bugs
2258 Your bug reports play an essential role in making the binary utilities
2261 Reporting a bug may help you by bringing a solution to your problem, or
2262 it may not. But in any case the principal function of a bug report is
2263 to help the entire community by making the next version of the binary
2264 utilities work better. Bug reports are your contribution to their
2267 In order for a bug report to serve its purpose, you must include the
2268 information that enables us to fix the bug.
2271 * Bug Criteria:: Have you found a bug?
2272 * Bug Reporting:: How to report bugs
2276 @section Have you found a bug?
2277 @cindex bug criteria
2279 If you are not sure whether you have found a bug, here are some guidelines:
2282 @cindex fatal signal
2285 If a binary utility gets a fatal signal, for any input whatever, that is
2286 a bug. Reliable utilities never crash.
2288 @cindex error on valid input
2290 If a binary utility produces an error message for valid input, that is a
2294 If you are an experienced user of binary utilities, your suggestions for
2295 improvement are welcome in any case.
2299 @section How to report bugs
2301 @cindex bugs, reporting
2303 A number of companies and individuals offer support for @sc{gnu}
2304 products. If you obtained the binary utilities from a support
2305 organization, we recommend you contact that organization first.
2307 You can find contact information for many support companies and
2308 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
2311 In any event, we also recommend that you send bug reports for the binary
2312 utilities to @samp{bug-gnu-utils@@gnu.org}.
2314 The fundamental principle of reporting bugs usefully is this:
2315 @strong{report all the facts}. If you are not sure whether to state a
2316 fact or leave it out, state it!
2318 Often people omit facts because they think they know what causes the
2319 problem and assume that some details do not matter. Thus, you might
2320 assume that the name of a file you use in an example does not matter.
2321 Well, probably it does not, but one cannot be sure. Perhaps the bug is
2322 a stray memory reference which happens to fetch from the location where
2323 that pathname is stored in memory; perhaps, if the pathname were
2324 different, the contents of that location would fool the utility into
2325 doing the right thing despite the bug. Play it safe and give a
2326 specific, complete example. That is the easiest thing for you to do,
2327 and the most helpful.
2329 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
2330 it is new to us. Therefore, always write your bug reports on the assumption
2331 that the bug has not been reported previously.
2333 Sometimes people give a few sketchy facts and ask, ``Does this ring a
2334 bell?'' Those bug reports are useless, and we urge everyone to
2335 @emph{refuse to respond to them} except to chide the sender to report
2338 To enable us to fix the bug, you should include all these things:
2342 The version of the utility. Each utility announces it if you start it
2343 with the @samp{--version} argument.
2345 Without this, we will not know whether there is any point in looking for
2346 the bug in the current version of the binary utilities.
2349 Any patches you may have applied to the source, including any patches
2350 made to the @code{BFD} library.
2353 The type of machine you are using, and the operating system name and
2357 What compiler (and its version) was used to compile the utilities---e.g.
2361 The command arguments you gave the utility to observe the bug. To
2362 guarantee you will not omit something important, list them all. A copy
2363 of the Makefile (or the output from make) is sufficient.
2365 If we were to try to guess the arguments, we would probably guess wrong
2366 and then we might not encounter the bug.
2369 A complete input file, or set of input files, that will reproduce the
2370 bug. If the utility is reading an object file or files, then it is
2371 generally most helpful to send the actual object files, uuencoded if
2372 necessary to get them through the mail system. Making them available
2373 for anonymous FTP is not as good, but may be the only reasonable choice
2374 for large object files.
2376 If the source files were produced exclusively using @sc{gnu} programs
2377 (e.g., @code{gcc}, @code{gas}, and/or the @sc{gnu} @code{ld}), then it
2378 may be OK to send the source files rather than the object files. In
2379 this case, be sure to say exactly what version of @code{gcc}, or
2380 whatever, was used to produce the object files. Also say how
2381 @code{gcc}, or whatever, was configured.
2384 A description of what behavior you observe that you believe is
2385 incorrect. For example, ``It gets a fatal signal.''
2387 Of course, if the bug is that the utility gets a fatal signal, then we
2388 will certainly notice it. But if the bug is incorrect output, we might
2389 not notice unless it is glaringly wrong. You might as well not give us
2390 a chance to make a mistake.
2392 Even if the problem you experience is a fatal signal, you should still
2393 say so explicitly. Suppose something strange is going on, such as, your
2394 copy of the utility is out of synch, or you have encountered a bug in
2395 the C library on your system. (This has happened!) Your copy might
2396 crash and ours would not. If you told us to expect a crash, then when
2397 ours fails to crash, we would know that the bug was not happening for
2398 us. If you had not told us to expect a crash, then we would not be able
2399 to draw any conclusion from our observations.
2402 If you wish to suggest changes to the source, send us context diffs, as
2403 generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
2404 option. Always send diffs from the old file to the new file. If you
2405 even discuss something in the @code{ld} source, refer to it by context,
2408 The line numbers in our development sources will not match those in your
2409 sources. Your line numbers would convey no useful information to us.
2412 Here are some things that are not necessary:
2416 A description of the envelope of the bug.
2418 Often people who encounter a bug spend a lot of time investigating
2419 which changes to the input file will make the bug go away and which
2420 changes will not affect it.
2422 This is often time consuming and not very useful, because the way we
2423 will find the bug is by running a single example under the debugger
2424 with breakpoints, not by pure deduction from a series of examples.
2425 We recommend that you save your time for something else.
2427 Of course, if you can find a simpler example to report @emph{instead}
2428 of the original one, that is a convenience for us. Errors in the
2429 output will be easier to spot, running under the debugger will take
2430 less time, and so on.
2432 However, simplification is not vital; if you do not want to do this,
2433 report the bug anyway and send us the entire test case you used.
2436 A patch for the bug.
2438 A patch for the bug does help us if it is a good one. But do not omit
2439 the necessary information, such as the test case, on the assumption that
2440 a patch is all we need. We might see problems with your patch and decide
2441 to fix the problem another way, or we might not understand it at all.
2443 Sometimes with programs as complicated as the binary utilities it is
2444 very hard to construct an example that will make the program follow a
2445 certain path through the code. If you do not send us the example, we
2446 will not be able to construct one, so we will not be able to verify that
2449 And if we cannot understand what bug you are trying to fix, or why your
2450 patch should be an improvement, we will not install it. A test case will
2451 help us to understand.
2454 A guess about what the bug is or what it depends on.
2456 Such guesses are usually wrong. Even we cannot guess right about such
2457 things without first using the debugger to find the facts.