2 This file documents the user interface to the GNU History library.
4 Copyright (C) 1988--2014 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 previous history line.
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{Bash Builtins}, 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). If @var{last} is not specified it is set to
153 @var{first}. If @var{first} is not specified it is set to the previous
154 command for editing and @minus{}16 for listing. If the @option{-l} flag is
155 given, the commands are listed on standard output. The @option{-n} flag
156 suppresses the command numbers when listing. The @option{-r} flag
157 reverses the order of the listing. Otherwise, the editor given by
158 @var{ename} is invoked on a file containing those commands. If
159 @var{ename} is not given, the value of the following variable expansion
160 is used: @code{$@{FCEDIT:-$@{EDITOR:-vi@}@}}. This says to use the
161 value of the @env{FCEDIT} variable if set, or the value of the
162 @env{EDITOR} variable if that is set, or @code{vi} if neither is set.
163 When editing is complete, the edited commands are echoed and executed.
165 In the second form, @var{command} is re-executed after each instance
166 of @var{pat} in the selected command is replaced by @var{rep}.
167 @var{command} is intepreted the same as @var{first} above.
169 A useful alias to use with the @code{fc} command is @code{r='fc -s'}, so
170 that typing @samp{r cc} runs the last command beginning with @code{cc}
171 and typing @samp{r} re-executes the last command (@pxref{Aliases}).
178 history -d @var{offset}
179 history [-anrw] [@var{filename}]
180 history -ps @var{arg}
183 With no options, display the history list with line numbers.
184 Lines prefixed with a @samp{*} have been modified.
185 An argument of @var{n} lists only the last @var{n} lines.
186 If the shell variable @env{HISTTIMEFORMAT} is set and not null,
187 it is used as a format string for @var{strftime} to display
188 the time stamp associated with each displayed history entry.
189 No intervening blank is printed between the formatted time stamp
190 and the history line.
192 Options, if supplied, have the following meanings:
196 Clear the history list. This may be combined
197 with the other options to replace the history list completely.
199 @item -d @var{offset}
200 Delete the history entry at position @var{offset}.
201 @var{offset} should be specified as it appears when the history is
205 Append the new history lines to the history file.
206 These are history lines entered since the beginning of the current
207 Bash session, but not already appended to the history file.
210 Append the history lines not already read from the history file
211 to the current history list. These are lines appended to the history
212 file since the beginning of the current Bash session.
215 Read the history file and append its contents to
219 Write out the current history list to the history file.
222 Perform history substitution on the @var{arg}s and display the result
223 on the standard output, without storing the results in the history list.
226 The @var{arg}s are added to the end of
227 the history list as a single entry.
231 When any of the @option{-w}, @option{-r}, @option{-a}, or @option{-n} options is
232 used, if @var{filename}
233 is given, then it is used as the history file. If not, then
234 the value of the @env{HISTFILE} variable is used.
239 @node History Interaction
240 @section History Expansion
241 @cindex history expansion
243 The History library provides a history expansion feature that is similar
244 to the history expansion provided by @code{csh}. This section
245 describes the syntax used to manipulate the history information.
247 History expansions introduce words from the history list into
248 the input stream, making it easy to repeat commands, insert the
249 arguments to a previous command into the current input line, or
250 fix errors in previous commands quickly.
252 History expansion takes place in two parts. The first is to determine
253 which line from the history list should be used during substitution.
254 The second is to select portions of that line for inclusion into the
255 current one. The line selected from the history is called the
256 @dfn{event}, and the portions of that line that are acted upon are
257 called @dfn{words}. Various @dfn{modifiers} are available to manipulate
258 the selected words. The line is broken into words in the same fashion
259 that Bash does, so that several words
260 surrounded by quotes are considered one word.
261 History expansions are introduced by the appearance of the
262 history expansion character, which is @samp{!} by default.
264 Only @samp{\} and @samp{'} may be used to escape the history expansion
269 Several shell options settable with the @code{shopt}
270 builtin (@pxref{Bash Builtins}) may be used to tailor
271 the behavior of history expansion. If the
272 @code{histverify} shell option is enabled, and Readline
273 is being used, history substitutions are not immediately passed to
275 Instead, the expanded line is reloaded into the Readline
276 editing buffer for further modification.
277 If Readline is being used, and the @code{histreedit}
278 shell option is enabled, a failed history expansion will be
279 reloaded into the Readline editing buffer for correction.
280 The @option{-p} option to the @code{history} builtin command
281 may be used to see what a history expansion will do before using it.
282 The @option{-s} option to the @code{history} builtin may be used to
283 add commands to the end of the history list without actually executing
284 them, so that they are available for subsequent recall.
285 This is most useful in conjunction with Readline.
287 The shell allows control of the various characters used by the
288 history expansion mechanism with the @code{histchars} variable,
289 as explained above (@pxref{Bash Variables}). The shell uses
290 the history comment character to mark history timestamps when
291 writing the history file.
295 * Event Designators:: How to specify which history line to use.
296 * Word Designators:: Specifying which words are of interest.
297 * Modifiers:: Modifying the results of substitution.
300 @node Event Designators
301 @subsection Event Designators
302 @cindex event designators
304 An event designator is a reference to a command line entry in the
306 Unless the reference is absolute, events are relative to the current
307 position in the history list.
308 @cindex history events
314 Start a history substitution, except when followed by a space, tab,
315 the end of the line, @samp{=} or @samp{(} (when the
316 @code{extglob} shell option is enabled using the @code{shopt} builtin).
318 @ifclear BashFeatures
319 Start a history substitution, except when followed by a space, tab,
320 the end of the line, or @samp{=}.
323 @item @code{!@var{n}}
324 Refer to command line @var{n}.
326 @item @code{!-@var{n}}
327 Refer to the command @var{n} lines back.
330 Refer to the previous command. This is a synonym for @samp{!-1}.
332 @item @code{!@var{string}}
333 Refer to the most recent command
334 preceding the current position in the history list
335 starting with @var{string}.
337 @item @code{!?@var{string}[?]}
338 Refer to the most recent command
339 preceding the current position in the history list
340 containing @var{string}.
342 @samp{?} may be omitted if the @var{string} is followed immediately by
345 @item @code{^@var{string1}^@var{string2}^}
346 Quick Substitution. Repeat the last command, replacing @var{string1}
347 with @var{string2}. Equivalent to
348 @code{!!:s/@var{string1}/@var{string2}/}.
351 The entire command line typed so far.
355 @node Word Designators
356 @subsection Word Designators
358 Word designators are used to select desired words from the event.
359 A @samp{:} separates the event specification from the word designator. It
360 may be omitted if the word designator begins with a @samp{^}, @samp{$},
361 @samp{*}, @samp{-}, or @samp{%}. Words are numbered from the beginning
362 of the line, with the first word being denoted by 0 (zero). Words are
363 inserted into the current line separated by single spaces.
370 designates the preceding command. When you type this, the preceding
371 command is repeated in toto.
374 designates the last argument of the preceding command. This may be
375 shortened to @code{!$}.
378 designates the second argument of the most recent command starting with
379 the letters @code{fi}.
383 Here are the word designators:
388 The @code{0}th word. For many applications, this is the command word.
394 The first argument; that is, word 1.
400 The word matched by the most recent @samp{?@var{string}?} search.
402 @item @var{x}-@var{y}
403 A range of words; @samp{-@var{y}} abbreviates @samp{0-@var{y}}.
406 All of the words, except the @code{0}th. This is a synonym for @samp{1-$}.
407 It is not an error to use @samp{*} if there is just one word in the event;
408 the empty string is returned in that case.
411 Abbreviates @samp{@var{x}-$}
414 Abbreviates @samp{@var{x}-$} like @samp{@var{x}*}, but omits the last word.
418 If a word designator is supplied without an event specification, the
419 previous command is used as the event.
422 @subsection Modifiers
424 After the optional word designator, you can add a sequence of one or more
425 of the following modifiers, each preceded by a @samp{:}.
430 Remove a trailing pathname component, leaving only the head.
433 Remove all leading pathname components, leaving the tail.
436 Remove a trailing suffix of the form @samp{.@var{suffix}}, leaving
440 Remove all but the trailing suffix.
443 Print the new command but do not execute it.
447 Quote the substituted words, escaping further substitutions.
450 Quote the substituted words as with @samp{q},
451 but break into words at spaces, tabs, and newlines.
454 @item s/@var{old}/@var{new}/
455 Substitute @var{new} for the first occurrence of @var{old} in the
456 event line. Any delimiter may be used in place of @samp{/}.
457 The delimiter may be quoted in @var{old} and @var{new}
458 with a single backslash. If @samp{&} appears in @var{new},
459 it is replaced by @var{old}. A single backslash will quote
460 the @samp{&}. The final delimiter is optional if it is the last
461 character on the input line.
464 Repeat the previous substitution.
468 Cause changes to be applied over the entire event line. Used in
469 conjunction with @samp{s}, as in @code{gs/@var{old}/@var{new}/},
473 Apply the following @samp{s} modifier once to each word in the event.