2 This file documents the user interface to the GNU History library.
4 Copyright (C) 1988--2016 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 GDB bundling modification:
30 @c @ifclear BashFeatures
35 This chapter describes how to use the @sc{gnu} History Library
36 interactively, from a user's standpoint.
37 It should be considered a user's guide.
38 For information on using the @sc{gnu} History Library in other programs,
39 see the @sc{gnu} Readline Library Manual.
42 This chapter describes how to use the @sc{gnu} History Library interactively,
43 from a user's standpoint. It should be considered a user's guide. For
44 information on using the @sc{gnu} History Library in your own programs,
45 @c GDB bundling modification:
46 @pxref{Programming with GNU History, , , history, GNU History Library}.
51 * Bash History Facilities:: How Bash lets you manipulate your command
53 * Bash History Builtins:: The Bash builtin commands that manipulate
55 * History Interaction:: What it feels like using History as a user.
60 * History Interaction:: What it feels like using History as a user.
65 @node Bash History Facilities
66 @section Bash History Facilities
67 @cindex command history
70 When the @option{-o history} option to the @code{set} builtin
71 is enabled (@pxref{The Set Builtin}),
72 the shell provides access to the @dfn{command history},
73 the list of commands previously typed.
74 The value of the @env{HISTSIZE} shell variable is used as the
75 number of commands to save in a history list.
76 The text of the last @env{$HISTSIZE}
77 commands (default 500) is saved.
78 The shell stores each command in the history list prior to
79 parameter and variable expansion
80 but after history expansion is performed, subject to the
81 values of the shell variables
82 @env{HISTIGNORE} and @env{HISTCONTROL}.
84 When the shell starts up, the history is initialized from the
85 file named by the @env{HISTFILE} variable (default @file{~/.bash_history}).
86 The file named by the value of @env{HISTFILE} is truncated, if
87 necessary, to contain no more than the number of lines specified by
88 the value of the @env{HISTFILESIZE} variable.
89 When a shell with history enabled exits, the last
90 @env{$HISTSIZE} lines are copied from the history list to the file
91 named by @env{$HISTFILE}.
92 If the @code{histappend} shell option is set (@pxref{Bash Builtins}),
93 the lines are appended to the history file,
94 otherwise the history file is overwritten.
96 is unset, or if the history file is unwritable, the history is not saved.
97 After saving the history, the history file is truncated
98 to contain no more than @env{$HISTFILESIZE} lines.
99 If @env{HISTFILESIZE} is unset, or set to null, a non-numeric value, or
100 a numeric value less than zero, the history file is not truncated.
102 If the @env{HISTTIMEFORMAT} is set, the time stamp information
103 associated with each history entry is written to the history file,
104 marked with the history comment character.
105 When the history file is read, lines beginning with the history
106 comment character followed immediately by a digit are interpreted
107 as timestamps for the following history entry.
109 The builtin command @code{fc} may be used to list or edit and re-execute
110 a portion of the history list.
111 The @code{history} builtin may be used to display or modify the history
112 list and manipulate the history file.
113 When using command-line editing, search commands
114 are available in each editing mode that provide access to the
115 history list (@pxref{Commands For History}).
117 The shell allows control over which commands are saved on the history
118 list. The @env{HISTCONTROL} and @env{HISTIGNORE}
119 variables may be set to cause the shell to save only a subset of the
122 shell option, if enabled, causes the shell to attempt to save each
123 line of a multi-line command in the same history entry, adding
124 semicolons where necessary to preserve syntactic correctness.
126 shell option causes the shell to save the command with embedded newlines
127 instead of semicolons.
128 The @code{shopt} builtin is used to set these options.
129 @xref{Bash Builtins}, for a description of @code{shopt}.
131 @node Bash History Builtins
132 @section Bash History Builtins
133 @cindex history builtins
135 Bash provides two builtin commands which manipulate the
136 history list and history file.
143 @code{fc [-e @var{ename}] [-lnr] [@var{first}] [@var{last}]}
144 @code{fc -s [@var{pat}=@var{rep}] [@var{command}]}
147 The first form selects a range of commands from @var{first} to
148 @var{last} from the history list and displays or edits and re-executes
151 @var{last} may be specified as a string (to locate the most recent
152 command beginning with that string) or as a number (an index into the
153 history list, where a negative number is used as an offset from the
154 current command number). If @var{last} is not specified it is set to
155 @var{first}. If @var{first} is not specified it is set to the previous
156 command for editing and @minus{}16 for listing. If the @option{-l} flag is
157 given, the commands are listed on standard output. The @option{-n} flag
158 suppresses the command numbers when listing. The @option{-r} flag
159 reverses the order of the listing. Otherwise, the editor given by
160 @var{ename} is invoked on a file containing those commands. If
161 @var{ename} is not given, the value of the following variable expansion
162 is used: @code{$@{FCEDIT:-$@{EDITOR:-vi@}@}}. This says to use the
163 value of the @env{FCEDIT} variable if set, or the value of the
164 @env{EDITOR} variable if that is set, or @code{vi} if neither is set.
165 When editing is complete, the edited commands are echoed and executed.
167 In the second form, @var{command} is re-executed after each instance
168 of @var{pat} in the selected command is replaced by @var{rep}.
169 @var{command} is intepreted the same as @var{first} above.
171 A useful alias to use with the @code{fc} command is @code{r='fc -s'}, so
172 that typing @samp{r cc} runs the last command beginning with @code{cc}
173 and typing @samp{r} re-executes the last command (@pxref{Aliases}).
180 history -d @var{offset}
181 history [-anrw] [@var{filename}]
182 history -ps @var{arg}
185 With no options, display the history list with line numbers.
186 Lines prefixed with a @samp{*} have been modified.
187 An argument of @var{n} lists only the last @var{n} lines.
188 If the shell variable @env{HISTTIMEFORMAT} is set and not null,
189 it is used as a format string for @var{strftime} to display
190 the time stamp associated with each displayed history entry.
191 No intervening blank is printed between the formatted time stamp
192 and the history line.
194 Options, if supplied, have the following meanings:
198 Clear the history list. This may be combined
199 with the other options to replace the history list completely.
201 @item -d @var{offset}
202 Delete the history entry at position @var{offset}.
203 @var{offset} should be specified as it appears when the history is
207 Append the new history lines to the history file.
208 These are history lines entered since the beginning of the current
209 Bash session, but not already appended to the history file.
212 Append the history lines not already read from the history file
213 to the current history list. These are lines appended to the history
214 file since the beginning of the current Bash session.
217 Read the history file and append its contents to
221 Write out the current history list to the history file.
224 Perform history substitution on the @var{arg}s and display the result
225 on the standard output, without storing the results in the history list.
228 The @var{arg}s are added to the end of
229 the history list as a single entry.
233 When any of the @option{-w}, @option{-r}, @option{-a}, or @option{-n} options is
234 used, if @var{filename}
235 is given, then it is used as the history file. If not, then
236 the value of the @env{HISTFILE} variable is used.
241 @node History Interaction
242 @section History Expansion
243 @cindex history expansion
245 The History library provides a history expansion feature that is similar
246 to the history expansion provided by @code{csh}. This section
247 describes the syntax used to manipulate the history information.
249 History expansions introduce words from the history list into
250 the input stream, making it easy to repeat commands, insert the
251 arguments to a previous command into the current input line, or
252 fix errors in previous commands quickly.
255 History expansion is performed immediately after a complete line
256 is read, before the shell breaks it into words.
259 History expansion takes place in two parts. The first is to determine
260 which line from the history list should be used during substitution.
261 The second is to select portions of that line for inclusion into the
262 current one. The line selected from the history is called the
263 @dfn{event}, and the portions of that line that are acted upon are
264 called @dfn{words}. Various @dfn{modifiers} are available to manipulate
265 the selected words. The line is broken into words in the same fashion
266 that Bash does, so that several words
267 surrounded by quotes are considered one word.
268 History expansions are introduced by the appearance of the
269 history expansion character, which is @samp{!} by default.
271 Only @samp{\} and @samp{'} may be used to escape the history expansion
272 character, but the history expansion character is
273 also treated as quoted if it immediately precedes the closing double quote
274 in a double-quoted string.
278 Several shell options settable with the @code{shopt}
279 builtin (@pxref{Bash Builtins}) may be used to tailor
280 the behavior of history expansion. If the
281 @code{histverify} shell option is enabled, and Readline
282 is being used, history substitutions are not immediately passed to
284 Instead, the expanded line is reloaded into the Readline
285 editing buffer for further modification.
286 If Readline is being used, and the @code{histreedit}
287 shell option is enabled, a failed history expansion will be
288 reloaded into the Readline editing buffer for correction.
289 The @option{-p} option to the @code{history} builtin command
290 may be used to see what a history expansion will do before using it.
291 The @option{-s} option to the @code{history} builtin may be used to
292 add commands to the end of the history list without actually executing
293 them, so that they are available for subsequent recall.
294 This is most useful in conjunction with Readline.
296 The shell allows control of the various characters used by the
297 history expansion mechanism with the @code{histchars} variable,
298 as explained above (@pxref{Bash Variables}). The shell uses
299 the history comment character to mark history timestamps when
300 writing the history file.
304 * Event Designators:: How to specify which history line to use.
305 * Word Designators:: Specifying which words are of interest.
306 * Modifiers:: Modifying the results of substitution.
309 @node Event Designators
310 @subsection Event Designators
311 @cindex event designators
313 An event designator is a reference to a command line entry in the
315 Unless the reference is absolute, events are relative to the current
316 position in the history list.
317 @cindex history events
323 Start a history substitution, except when followed by a space, tab,
324 the end of the line, @samp{=} or @samp{(} (when the
325 @code{extglob} shell option is enabled using the @code{shopt} builtin).
327 @ifclear BashFeatures
328 Start a history substitution, except when followed by a space, tab,
329 the end of the line, or @samp{=}.
332 @item @code{!@var{n}}
333 Refer to command line @var{n}.
335 @item @code{!-@var{n}}
336 Refer to the command @var{n} lines back.
339 Refer to the previous command. This is a synonym for @samp{!-1}.
341 @item @code{!@var{string}}
342 Refer to the most recent command
343 preceding the current position in the history list
344 starting with @var{string}.
346 @item @code{!?@var{string}[?]}
347 Refer to the most recent command
348 preceding the current position in the history list
349 containing @var{string}.
351 @samp{?} may be omitted if the @var{string} is followed immediately by
354 @item @code{^@var{string1}^@var{string2}^}
355 Quick Substitution. Repeat the last command, replacing @var{string1}
356 with @var{string2}. Equivalent to
357 @code{!!:s/@var{string1}/@var{string2}/}.
360 The entire command line typed so far.
364 @node Word Designators
365 @subsection Word Designators
367 Word designators are used to select desired words from the event.
368 A @samp{:} separates the event specification from the word designator. It
369 may be omitted if the word designator begins with a @samp{^}, @samp{$},
370 @samp{*}, @samp{-}, or @samp{%}. Words are numbered from the beginning
371 of the line, with the first word being denoted by 0 (zero). Words are
372 inserted into the current line separated by single spaces.
379 designates the preceding command. When you type this, the preceding
380 command is repeated in toto.
383 designates the last argument of the preceding command. This may be
384 shortened to @code{!$}.
387 designates the second argument of the most recent command starting with
388 the letters @code{fi}.
392 Here are the word designators:
397 The @code{0}th word. For many applications, this is the command word.
403 The first argument; that is, word 1.
409 The word matched by the most recent @samp{?@var{string}?} search.
411 @item @var{x}-@var{y}
412 A range of words; @samp{-@var{y}} abbreviates @samp{0-@var{y}}.
415 All of the words, except the @code{0}th. This is a synonym for @samp{1-$}.
416 It is not an error to use @samp{*} if there is just one word in the event;
417 the empty string is returned in that case.
420 Abbreviates @samp{@var{x}-$}
423 Abbreviates @samp{@var{x}-$} like @samp{@var{x}*}, but omits the last word.
427 If a word designator is supplied without an event specification, the
428 previous command is used as the event.
431 @subsection Modifiers
433 After the optional word designator, you can add a sequence of one or more
434 of the following modifiers, each preceded by a @samp{:}.
439 Remove a trailing pathname component, leaving only the head.
442 Remove all leading pathname components, leaving the tail.
445 Remove a trailing suffix of the form @samp{.@var{suffix}}, leaving
449 Remove all but the trailing suffix.
452 Print the new command but do not execute it.
456 Quote the substituted words, escaping further substitutions.
459 Quote the substituted words as with @samp{q},
460 but break into words at spaces, tabs, and newlines.
463 @item s/@var{old}/@var{new}/
464 Substitute @var{new} for the first occurrence of @var{old} in the
465 event line. Any delimiter may be used in place of @samp{/}.
466 The delimiter may be quoted in @var{old} and @var{new}
467 with a single backslash. If @samp{&} appears in @var{new},
468 it is replaced by @var{old}. A single backslash will quote
469 the @samp{&}. The final delimiter is optional if it is the last
470 character on the input line.
473 Repeat the previous substitution.
477 Cause changes to be applied over the entire event line. Used in
478 conjunction with @samp{s}, as in @code{gs/@var{old}/@var{new}/},
482 Apply the following @samp{s} modifier once to each word in the event.