2 This file documents the user interface to the GNU History library.
4 Copyright (C) 1988-1999 Free Software Foundation, Inc.
5 Authored by Brian Fox and Chet Ramey.
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26 @node Using History Interactively
27 @chapter Using History Interactively
29 @c @ifclear BashFeatures
34 This chapter describes how to use the @sc{gnu} History Library
35 interactively, from a user's standpoint.
36 It should be considered a user's guide.
37 For information on using the @sc{gnu} History Library in other programs,
38 see the @sc{gnu} Readline Library Manual.
41 This chapter describes how to use the GNU History Library interactively,
42 from a user's standpoint. It should be considered a user's guide.
44 @c information on using the GNU History Library in your own programs,
45 @c @pxref{Programming with GNU History}.
50 * Bash History Facilities:: How Bash lets you manipulate your command
52 * Bash History Builtins:: The Bash builtin commands that manipulate
54 * History Interaction:: What it feels like using History as a user.
59 * History Interaction:: What it feels like using History as a user.
64 @node Bash History Facilities
65 @section Bash History Facilities
66 @cindex command history
69 When the @samp{-o history} option to the @code{set} builtin
70 is enabled (@pxref{The Set Builtin}),
71 the shell provides access to the @var{command history},
72 the list of commands previously typed.
73 The value of the @code{HISTSIZE} shell variable is used as the
74 number of commands to save in a history list.
75 The text of the last @code{$HISTSIZE}
76 commands (default 500) is saved.
77 The shell stores each command in the history list prior to
78 parameter and variable expansion
79 but after history expansion is performed, subject to the
80 values of the shell variables
81 @code{HISTIGNORE} and @code{HISTCONTROL}.
83 When the shell starts up, the history is initialized from the
84 file named by the @code{HISTFILE} variable (default @file{~/.bash_history}).
85 The file named by the value of @code{HISTFILE} is truncated, if
86 necessary, to contain no more than the number of lines specified by
87 the value of the @code{HISTFILESIZE} variable.
88 When an interactive shell exits, the last
89 @code{$HISTSIZE} lines are copied from the history list to the file
90 named by @code{$HISTFILE}.
91 If the @code{histappend} shell option is set (@pxref{Bash Builtins}),
92 the lines are appended to the history file,
93 otherwise the history file is overwritten.
95 is unset, or if the history file is unwritable, the history is
96 not saved. After saving the history, the history file is truncated
97 to contain no more than @code{$HISTFILESIZE}
98 lines. If @code{HISTFILESIZE} is not set, no truncation is performed.
100 The builtin command @code{fc} may be used to list or edit and re-execute
101 a portion of the history list.
102 The @code{history} builtin may be used to display or modify the history
103 list and manipulate the history file.
104 When using command-line editing, search commands
105 are available in each editing mode that provide access to the
106 history list (@pxref{Commands For History}).
108 The shell allows control over which commands are saved on the history
109 list. The @code{HISTCONTROL} and @code{HISTIGNORE}
110 variables may be set to cause the shell to save only a subset of the
113 shell option, if enabled, causes the shell to attempt to save each
114 line of a multi-line command in the same history entry, adding
115 semicolons where necessary to preserve syntactic correctness.
117 shell option causes the shell to save the command with embedded newlines
118 instead of semicolons.
119 The @code{shopt} builtin is used to set these options.
120 @xref{Bash Builtins}, for a description of @code{shopt}.
122 @node Bash History Builtins
123 @section Bash History Builtins
124 @cindex history builtins
126 Bash provides two builtin commands which manipulate the
127 history list and history file.
134 @code{fc [-e @var{ename}] [-nlr] [@var{first}] [@var{last}]}
135 @code{fc -s [@var{pat}=@var{rep}] [@var{command}]}
138 Fix Command. In the first form, a range of commands from @var{first} to
139 @var{last} is selected from the history list. Both @var{first} and
140 @var{last} may be specified as a string (to locate the most recent
141 command beginning with that string) or as a number (an index into the
142 history list, where a negative number is used as an offset from the
143 current command number). If @var{last} is not specified it is set to
144 @var{first}. If @var{first} is not specified it is set to the previous
145 command for editing and @minus{}16 for listing. If the @samp{-l} flag is
146 given, the commands are listed on standard output. The @samp{-n} flag
147 suppresses the command numbers when listing. The @samp{-r} flag
148 reverses the order of the listing. Otherwise, the editor given by
149 @var{ename} is invoked on a file containing those commands. If
150 @var{ename} is not given, the value of the following variable expansion
151 is used: @code{$@{FCEDIT:-$@{EDITOR:-vi@}@}}. This says to use the
152 value of the @code{FCEDIT} variable if set, or the value of the
153 @code{EDITOR} variable if that is set, or @code{vi} if neither is set.
154 When editing is complete, the edited commands are echoed and executed.
156 In the second form, @var{command} is re-executed after each instance
157 of @var{pat} in the selected command is replaced by @var{rep}.
159 A useful alias to use with the @code{fc} command is @code{r='fc -s'}, so
160 that typing @samp{r cc} runs the last command beginning with @code{cc}
161 and typing @samp{r} re-executes the last command (@pxref{Aliases}).
168 history -d @var{offset}
169 history [-anrw] [@var{filename}]
170 history -ps @var{arg}
173 With no options, display the history list with line numbers.
174 Lines prefixed with with a @samp{*} have been modified.
175 An argument of @var{n} lists only the last @var{n} lines.
176 Options, if supplied, have the following meanings:
180 Clear the history list. This may be combined
181 with the other options to replace the history list completely.
183 @item -d @var{offset}
184 Delete the history entry at position @var{offset}.
185 @var{offset} should be specified as it appears when the history is
190 history lines (history lines entered since the beginning of the
191 current Bash session) to the history file.
194 Append the history lines not already read from the history file
195 to the current history list. These are lines appended to the history
196 file since the beginning of the current Bash session.
199 Read the current history file and append its contents to
203 Write out the current history to the history file.
206 Perform history substitution on the @var{arg}s and display the result
207 on the standard output, without storing the results in the history list.
210 The @var{arg}s are added to the end of
211 the history list as a single entry.
215 When any of the @samp{-w}, @samp{-r}, @samp{-a}, or @samp{-n} options is
216 used, if @var{filename}
217 is given, then it is used as the history file. If not, then
218 the value of the @code{HISTFILE} variable is used.
223 @node History Interaction
224 @section History Expansion
225 @cindex history expansion
227 The History library provides a history expansion feature that is similar
228 to the history expansion provided by @code{csh}. This section
229 describes the syntax used to manipulate the history information.
231 History expansions introduce words from the history list into
232 the input stream, making it easy to repeat commands, insert the
233 arguments to a previous command into the current input line, or
234 fix errors in previous commands quickly.
236 History expansion takes place in two parts. The first is to determine
237 which line from the history list should be used during substitution.
238 The second is to select portions of that line for inclusion into the
239 current one. The line selected from the history is called the
240 @dfn{event}, and the portions of that line that are acted upon are
241 called @dfn{words}. Various @dfn{modifiers} are available to manipulate
242 the selected words. The line is broken into words in the same fashion
243 that Bash does, so that several words
244 surrounded by quotes are considered one word.
245 History expansions are introduced by the appearance of the
246 history expansion character, which is @samp{!} by default.
248 Only @samp{\} and @samp{'} may be used to escape the history expansion
253 Several shell options settable with the @code{shopt}
254 builtin (@pxref{Bash Builtins}) may be used to tailor
255 the behavior of history expansion. If the
256 @code{histverify} shell option is enabled, and Readline
257 is being used, history substitutions are not immediately passed to
259 Instead, the expanded line is reloaded into the Readline
260 editing buffer for further modification.
261 If Readline is being used, and the @code{histreedit}
262 shell option is enabled, a failed history expansion will be
263 reloaded into the Readline editing buffer for correction.
264 The @samp{-p} option to the @code{history} builtin command
265 may be used to see what a history expansion will do before using it.
266 The @samp{-s} option to the @code{history} builtin may be used to
267 add commands to the end of the history list without actually executing
268 them, so that they are available for subsequent recall.
269 This is most useful in conjunction with Readline.
271 The shell allows control of the various characters used by the
272 history expansion mechanism with the @code{histchars} variable.
276 * Event Designators:: How to specify which history line to use.
277 * Word Designators:: Specifying which words are of interest.
278 * Modifiers:: Modifying the results of substitution.
281 @node Event Designators
282 @subsection Event Designators
283 @cindex event designators
285 An event designator is a reference to a command line entry in the
287 @cindex history events
292 Start a history substitution, except when followed by a space, tab,
293 the end of the line, @samp{=} or @samp{(}.
295 @item @code{!@var{n}}
296 Refer to command line @var{n}.
298 @item @code{!-@var{n}}
299 Refer to the command @var{n} lines back.
302 Refer to the previous command. This is a synonym for @samp{!-1}.
304 @item @code{!@var{string}}
305 Refer to the most recent command starting with @var{string}.
307 @item @code{!?@var{string}[?]}
308 Refer to the most recent command containing @var{string}. The trailing
309 @samp{?} may be omitted if the @var{string} is followed immediately by
312 @item @code{^@var{string1}^@var{string2}^}
313 Quick Substitution. Repeat the last command, replacing @var{string1}
314 with @var{string2}. Equivalent to
315 @code{!!:s/@var{string1}/@var{string2}/}.
318 The entire command line typed so far.
322 @node Word Designators
323 @subsection Word Designators
325 Word designators are used to select desired words from the event.
326 A @samp{:} separates the event specification from the word designator. It
327 may be omitted if the word designator begins with a @samp{^}, @samp{$},
328 @samp{*}, @samp{-}, or @samp{%}. Words are numbered from the beginning
329 of the line, with the first word being denoted by 0 (zero). Words are
330 inserted into the current line separated by single spaces.
337 designates the preceding command. When you type this, the preceding
338 command is repeated in toto.
341 designates the last argument of the preceding command. This may be
342 shortened to @code{!$}.
345 designates the second argument of the most recent command starting with
346 the letters @code{fi}.
350 Here are the word designators:
355 The @code{0}th word. For many applications, this is the command word.
361 The first argument; that is, word 1.
367 The word matched by the most recent @samp{?@var{string}?} search.
369 @item @var{x}-@var{y}
370 A range of words; @samp{-@var{y}} abbreviates @samp{0-@var{y}}.
373 All of the words, except the @code{0}th. This is a synonym for @samp{1-$}.
374 It is not an error to use @samp{*} if there is just one word in the event;
375 the empty string is returned in that case.
378 Abbreviates @samp{@var{x}-$}
381 Abbreviates @samp{@var{x}-$} like @samp{@var{x}*}, but omits the last word.
385 If a word designator is supplied without an event specification, the
386 previous command is used as the event.
389 @subsection Modifiers
391 After the optional word designator, you can add a sequence of one or more
392 of the following modifiers, each preceded by a @samp{:}.
397 Remove a trailing pathname component, leaving only the head.
400 Remove all leading pathname components, leaving the tail.
403 Remove a trailing suffix of the form @samp{.@var{suffix}}, leaving
407 Remove all but the trailing suffix.
410 Print the new command but do not execute it.
414 Quote the substituted words, escaping further substitutions.
417 Quote the substituted words as with @samp{q},
418 but break into words at spaces, tabs, and newlines.
421 @item s/@var{old}/@var{new}/
422 Substitute @var{new} for the first occurrence of @var{old} in the
423 event line. Any delimiter may be used in place of @samp{/}.
424 The delimiter may be quoted in @var{old} and @var{new}
425 with a single backslash. If @samp{&} appears in @var{new},
426 it is replaced by @var{old}. A single backslash will quote
427 the @samp{&}. The final delimiter is optional if it is the last
428 character on the input line.
431 Repeat the previous substitution.
434 Cause changes to be applied over the entire event line. Used in
435 conjunction with @samp{s}, as in @code{gs/@var{old}/@var{new}/},