2 This file documents the user interface to the GNU History library.
4 Copyright (C) 1988--2022 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
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 @sc{gnu} History Library interactively,
42 from a user's standpoint. It should be considered a user's guide. For
43 information on using the @sc{gnu} History Library in your own programs,
44 @pxref{Programming with GNU History}.
49 * Bash History Facilities:: How Bash lets you manipulate your command
51 * Bash History Builtins:: The Bash builtin commands that manipulate
53 * History Interaction:: What it feels like using History as a user.
58 * History Interaction:: What it feels like using History as a user.
63 @node Bash History Facilities
64 @section Bash History Facilities
65 @cindex command history
68 When the @option{-o history} option to the @code{set} builtin
69 is enabled (@pxref{The Set Builtin}),
70 the shell provides access to the @dfn{command history},
71 the list of commands previously typed.
72 The value of the @env{HISTSIZE} shell variable is used as the
73 number of commands to save in a history list.
74 The text of the last @env{$HISTSIZE}
75 commands (default 500) is saved.
76 The shell stores each command in the history list prior to
77 parameter and variable expansion
78 but after history expansion is performed, subject to the
79 values of the shell variables
80 @env{HISTIGNORE} and @env{HISTCONTROL}.
82 When the shell starts up, the history is initialized from the
83 file named by the @env{HISTFILE} variable (default @file{~/.bash_history}).
84 The file named by the value of @env{HISTFILE} is truncated, if
85 necessary, to contain no more than the number of lines specified by
86 the value of the @env{HISTFILESIZE} variable.
87 When a shell with history enabled exits, the last
88 @env{$HISTSIZE} lines are copied from the history list to the file
89 named by @env{$HISTFILE}.
90 If the @code{histappend} shell option is set (@pxref{Bash Builtins}),
91 the lines are appended to the history file,
92 otherwise the history file is overwritten.
94 is unset, or if the history file is unwritable, the history is not saved.
95 After saving the history, the history file is truncated
96 to contain no more than @env{$HISTFILESIZE} lines.
97 If @env{HISTFILESIZE} is unset, or set to null, a non-numeric value, or
98 a numeric value less than zero, the history file is not truncated.
100 If the @env{HISTTIMEFORMAT} is set, the time stamp information
101 associated with each history entry is written to the history file,
102 marked with the history comment character.
103 When the history file is read, lines beginning with the history
104 comment character followed immediately by a digit are interpreted
105 as timestamps for the following history entry.
107 The builtin command @code{fc} may be used to list or edit and re-execute
108 a portion of the history list.
109 The @code{history} builtin may be used to display or modify the history
110 list and manipulate the history file.
111 When using command-line editing, search commands
112 are available in each editing mode that provide access to the
113 history list (@pxref{Commands For History}).
115 The shell allows control over which commands are saved on the history
116 list. The @env{HISTCONTROL} and @env{HISTIGNORE}
117 variables may be set to cause the shell to save only a subset of the
120 shell option, if enabled, causes the shell to attempt to save each
121 line of a multi-line command in the same history entry, adding
122 semicolons where necessary to preserve syntactic correctness.
124 shell option causes the shell to save the command with embedded newlines
125 instead of semicolons.
126 The @code{shopt} builtin is used to set these options.
127 @xref{The Shopt Builtin}, for a description of @code{shopt}.
129 @node Bash History Builtins
130 @section Bash History Builtins
131 @cindex history builtins
133 Bash provides two builtin commands which manipulate the
134 history list and history file.
141 @code{fc [-e @var{ename}] [-lnr] [@var{first}] [@var{last}]}
142 @code{fc -s [@var{pat}=@var{rep}] [@var{command}]}
145 The first form selects a range of commands from @var{first} to
146 @var{last} from the history list and displays or edits and re-executes
149 @var{last} may be specified as a string (to locate the most recent
150 command beginning with that string) or as a number (an index into the
151 history list, where a negative number is used as an offset from the
152 current command number).
154 When listing, a @var{first} or @var{last} of 0 is equivalent to -1
155 and -0 is equivalent to the current command (usually the @code{fc}
157 otherwise 0 is equivalent to -1 and -0 is invalid.
159 If @var{last} is not specified, it is set to
160 @var{first}. If @var{first} is not specified, it is set to the previous
161 command for editing and @minus{}16 for listing. If the @option{-l} flag is
162 given, the commands are listed on standard output. The @option{-n} flag
163 suppresses the command numbers when listing. The @option{-r} flag
164 reverses the order of the listing. Otherwise, the editor given by
165 @var{ename} is invoked on a file containing those commands. If
166 @var{ename} is not given, the value of the following variable expansion
167 is used: @code{$@{FCEDIT:-$@{EDITOR:-vi@}@}}. This says to use the
168 value of the @env{FCEDIT} variable if set, or the value of the
169 @env{EDITOR} variable if that is set, or @code{vi} if neither is set.
170 When editing is complete, the edited commands are echoed and executed.
172 In the second form, @var{command} is re-executed after each instance
173 of @var{pat} in the selected command is replaced by @var{rep}.
174 @var{command} is interpreted the same as @var{first} above.
176 A useful alias to use with the @code{fc} command is @code{r='fc -s'}, so
177 that typing @samp{r cc} runs the last command beginning with @code{cc}
178 and typing @samp{r} re-executes the last command (@pxref{Aliases}).
185 history -d @var{offset}
186 history -d @var{start}-@var{end}
187 history [-anrw] [@var{filename}]
188 history -ps @var{arg}
191 With no options, display the history list with line numbers.
192 Lines prefixed with a @samp{*} have been modified.
193 An argument of @var{n} lists only the last @var{n} lines.
194 If the shell variable @env{HISTTIMEFORMAT} is set and not null,
195 it is used as a format string for @var{strftime} to display
196 the time stamp associated with each displayed history entry.
197 No intervening blank is printed between the formatted time stamp
198 and the history line.
200 Options, if supplied, have the following meanings:
204 Clear the history list. This may be combined
205 with the other options to replace the history list completely.
207 @item -d @var{offset}
208 Delete the history entry at position @var{offset}.
209 If @var{offset} is positive, it should be specified as it appears when
210 the history is displayed.
211 If @var{offset} is negative, it is interpreted as relative to one greater
212 than the last history position, so negative indices count back from the
213 end of the history, and an index of @samp{-1} refers to the current
214 @code{history -d} command.
216 @item -d @var{start}-@var{end}
217 Delete the range of history entries between positions @var{start} and
218 @var{end}, inclusive.
219 Positive and negative values for @var{start} and @var{end}
220 are interpreted as described above.
223 Append the new history lines to the history file.
224 These are history lines entered since the beginning of the current
225 Bash session, but not already appended to the history file.
228 Append the history lines not already read from the history file
229 to the current history list. These are lines appended to the history
230 file since the beginning of the current Bash session.
233 Read the history file and append its contents to
237 Write out the current history list to the history file.
240 Perform history substitution on the @var{arg}s and display the result
241 on the standard output, without storing the results in the history list.
244 The @var{arg}s are added to the end of
245 the history list as a single entry.
249 If a @var{filename} argument is supplied
250 when any of the @option{-w}, @option{-r}, @option{-a}, or @option{-n} options
251 is used, Bash uses @var{filename} as the history file.
252 If not, then the value of the @env{HISTFILE} variable is used.
254 The return value is 0 unless an invalid option is encountered, an
255 error occurs while reading or writing the history file, an invalid
256 @var{offset} or range is supplied as an argument to @option{-d}, or the
257 history expansion supplied as an argument to @option{-p} fails.
262 @node History Interaction
263 @section History Expansion
264 @cindex history expansion
266 The History library provides a history expansion feature that is similar
267 to the history expansion provided by @code{csh}. This section
268 describes the syntax used to manipulate the history information.
270 History expansions introduce words from the history list into
271 the input stream, making it easy to repeat commands, insert the
272 arguments to a previous command into the current input line, or
273 fix errors in previous commands quickly.
276 History expansion is performed immediately after a complete line
277 is read, before the shell breaks it into words, and is performed
278 on each line individually. Bash attempts to inform the history
279 expansion functions about quoting still in effect from previous lines.
282 History expansion takes place in two parts. The first is to determine
283 which line from the history list should be used during substitution.
284 The second is to select portions of that line for inclusion into the
285 current one. The line selected from the history is called the
286 @dfn{event}, and the portions of that line that are acted upon are
287 called @dfn{words}. Various @dfn{modifiers} are available to manipulate
288 the selected words. The line is broken into words in the same fashion
289 that Bash does, so that several words
290 surrounded by quotes are considered one word.
291 History expansions are introduced by the appearance of the
292 history expansion character, which is @samp{!} by default.
294 History expansion implements shell-like quoting conventions:
295 a backslash can be used to remove the special handling for the next character;
296 single quotes enclose verbatim sequences of characters, and can be used to
297 inhibit history expansion;
298 and characters enclosed within double quotes may be subject to history
299 expansion, since backslash can escape the history expansion character,
300 but single quotes may not, since they are not treated specially within
304 When using the shell, only @samp{\} and @samp{'} may be used to escape the
305 history expansion character, but the history expansion character is
306 also treated as quoted if it immediately precedes the closing double quote
307 in a double-quoted string.
311 Several shell options settable with the @code{shopt}
312 builtin (@pxref{The Shopt Builtin}) may be used to tailor
313 the behavior of history expansion. If the
314 @code{histverify} shell option is enabled, and Readline
315 is being used, history substitutions are not immediately passed to
317 Instead, the expanded line is reloaded into the Readline
318 editing buffer for further modification.
319 If Readline is being used, and the @code{histreedit}
320 shell option is enabled, a failed history expansion will be
321 reloaded into the Readline editing buffer for correction.
322 The @option{-p} option to the @code{history} builtin command
323 may be used to see what a history expansion will do before using it.
324 The @option{-s} option to the @code{history} builtin may be used to
325 add commands to the end of the history list without actually executing
326 them, so that they are available for subsequent recall.
327 This is most useful in conjunction with Readline.
329 The shell allows control of the various characters used by the
330 history expansion mechanism with the @code{histchars} variable,
331 as explained above (@pxref{Bash Variables}). The shell uses
332 the history comment character to mark history timestamps when
333 writing the history file.
337 * Event Designators:: How to specify which history line to use.
338 * Word Designators:: Specifying which words are of interest.
339 * Modifiers:: Modifying the results of substitution.
342 @node Event Designators
343 @subsection Event Designators
344 @cindex event designators
346 An event designator is a reference to a command line entry in the
348 Unless the reference is absolute, events are relative to the current
349 position in the history list.
350 @cindex history events
356 Start a history substitution, except when followed by a space, tab,
357 the end of the line, @samp{=} or @samp{(} (when the
358 @code{extglob} shell option is enabled using the @code{shopt} builtin).
360 @ifclear BashFeatures
361 Start a history substitution, except when followed by a space, tab,
362 the end of the line, or @samp{=}.
365 @item @code{!@var{n}}
366 Refer to command line @var{n}.
368 @item @code{!-@var{n}}
369 Refer to the command @var{n} lines back.
372 Refer to the previous command. This is a synonym for @samp{!-1}.
374 @item @code{!@var{string}}
375 Refer to the most recent command
376 preceding the current position in the history list
377 starting with @var{string}.
379 @item @code{!?@var{string}[?]}
380 Refer to the most recent command
381 preceding the current position in the history list
382 containing @var{string}.
384 @samp{?} may be omitted if the @var{string} is followed immediately by
386 If @var{string} is missing, the string from the most recent search is used;
387 it is an error if there is no previous search string.
389 @item @code{^@var{string1}^@var{string2}^}
390 Quick Substitution. Repeat the last command, replacing @var{string1}
391 with @var{string2}. Equivalent to
392 @code{!!:s^@var{string1}^@var{string2}^}.
395 The entire command line typed so far.
399 @node Word Designators
400 @subsection Word Designators
402 Word designators are used to select desired words from the event.
403 A @samp{:} separates the event specification from the word designator. It
404 may be omitted if the word designator begins with a @samp{^}, @samp{$},
405 @samp{*}, @samp{-}, or @samp{%}. Words are numbered from the beginning
406 of the line, with the first word being denoted by 0 (zero). Words are
407 inserted into the current line separated by single spaces.
414 designates the preceding command. When you type this, the preceding
415 command is repeated in toto.
418 designates the last argument of the preceding command. This may be
419 shortened to @code{!$}.
422 designates the second argument of the most recent command starting with
423 the letters @code{fi}.
427 Here are the word designators:
432 The @code{0}th word. For many applications, this is the command word.
438 The first argument; that is, word 1.
444 The first word matched by the most recent @samp{?@var{string}?} search,
445 if the search string begins with a character that is part of a word.
447 @item @var{x}-@var{y}
448 A range of words; @samp{-@var{y}} abbreviates @samp{0-@var{y}}.
451 All of the words, except the @code{0}th. This is a synonym for @samp{1-$}.
452 It is not an error to use @samp{*} if there is just one word in the event;
453 the empty string is returned in that case.
456 Abbreviates @samp{@var{x}-$}
459 Abbreviates @samp{@var{x}-$} like @samp{@var{x}*}, but omits the last word.
460 If @samp{x} is missing, it defaults to 0.
464 If a word designator is supplied without an event specification, the
465 previous command is used as the event.
468 @subsection Modifiers
470 After the optional word designator, you can add a sequence of one or more
471 of the following modifiers, each preceded by a @samp{:}.
472 These modify, or edit, the word or words selected from the history event.
477 Remove a trailing pathname component, leaving only the head.
480 Remove all leading pathname components, leaving the tail.
483 Remove a trailing suffix of the form @samp{.@var{suffix}}, leaving
487 Remove all but the trailing suffix.
490 Print the new command but do not execute it.
494 Quote the substituted words, escaping further substitutions.
497 Quote the substituted words as with @samp{q},
498 but break into words at spaces, tabs, and newlines.
499 The @samp{q} and @samp{x} modifiers are mutually exclusive; the last one
503 @item s/@var{old}/@var{new}/
504 Substitute @var{new} for the first occurrence of @var{old} in the
506 Any character may be used as the delimiter in place of @samp{/}.
507 The delimiter may be quoted in @var{old} and @var{new}
508 with a single backslash. If @samp{&} appears in @var{new},
509 it is replaced by @var{old}. A single backslash will quote
511 If @var{old} is null, it is set to the last @var{old}
512 substituted, or, if no previous history substitutions took place,
513 the last @var{string}
514 in a !?@var{string}@code{[?]}
516 If @var{new} is null, each matching @var{old} is deleted.
517 The final delimiter is optional if it is the last
518 character on the input line.
521 Repeat the previous substitution.
525 Cause changes to be applied over the entire event line. Used in
526 conjunction with @samp{s}, as in @code{gs/@var{old}/@var{new}/},
530 Apply the following @samp{s} or @samp{&} modifier once to each word