diff options
Diffstat (limited to '')
| -rw-r--r-- | doc/hsuser.texi | 527 |
1 files changed, 527 insertions, 0 deletions
diff --git a/doc/hsuser.texi b/doc/hsuser.texi new file mode 100644 index 0000000..b8fedf3 --- /dev/null +++ b/doc/hsuser.texi @@ -0,0 +1,527 @@ +@ignore +This file documents the user interface to the GNU History library. + +Copyright (C) 1988--2020 Free Software Foundation, Inc. +Authored by Brian Fox and Chet Ramey. + +Permission is granted to make and distribute verbatim copies of this manual +provided the copyright notice and this permission notice are preserved on +all copies. + +Permission is granted to process this file through Tex and print the +results, provided the printed document carries copying permission notice +identical to this one except for the removal of this paragraph (this +paragraph not being relevant to the printed manual). + +Permission is granted to copy and distribute modified versions of this +manual under the conditions for verbatim copying, provided also that the +GNU Copyright statement is available to the distributee, and provided that +the entire resulting derived work is distributed under the terms of a +permission notice identical to this one. + +Permission is granted to copy and distribute translations of this manual +into another language, under the above conditions for modified versions. +@end ignore + +@node Using History Interactively +@chapter Using History Interactively + +@ifclear BashFeatures +@defcodeindex bt +@end ifclear + +@ifset BashFeatures +This chapter describes how to use the @sc{gnu} History Library +interactively, from a user's standpoint. +It should be considered a user's guide. +For information on using the @sc{gnu} History Library in other programs, +see the @sc{gnu} Readline Library Manual. +@end ifset +@ifclear BashFeatures +This chapter describes how to use the @sc{gnu} History Library interactively, +from a user's standpoint. It should be considered a user's guide. For +information on using the @sc{gnu} History Library in your own programs, +@pxref{Programming with GNU History}. +@end ifclear + +@ifset BashFeatures +@menu +* Bash History Facilities:: How Bash lets you manipulate your command + history. +* Bash History Builtins:: The Bash builtin commands that manipulate + the command history. +* History Interaction:: What it feels like using History as a user. +@end menu +@end ifset +@ifclear BashFeatures +@menu +* History Interaction:: What it feels like using History as a user. +@end menu +@end ifclear + +@ifset BashFeatures +@node Bash History Facilities +@section Bash History Facilities +@cindex command history +@cindex history list + +When the @option{-o history} option to the @code{set} builtin +is enabled (@pxref{The Set Builtin}), +the shell provides access to the @dfn{command history}, +the list of commands previously typed. +The value of the @env{HISTSIZE} shell variable is used as the +number of commands to save in a history list. +The text of the last @env{$HISTSIZE} +commands (default 500) is saved. +The shell stores each command in the history list prior to +parameter and variable expansion +but after history expansion is performed, subject to the +values of the shell variables +@env{HISTIGNORE} and @env{HISTCONTROL}. + +When the shell starts up, the history is initialized from the +file named by the @env{HISTFILE} variable (default @file{~/.bash_history}). +The file named by the value of @env{HISTFILE} is truncated, if +necessary, to contain no more than the number of lines specified by +the value of the @env{HISTFILESIZE} variable. +When a shell with history enabled exits, the last +@env{$HISTSIZE} lines are copied from the history list to the file +named by @env{$HISTFILE}. +If the @code{histappend} shell option is set (@pxref{Bash Builtins}), +the lines are appended to the history file, +otherwise the history file is overwritten. +If @env{HISTFILE} +is unset, or if the history file is unwritable, the history is not saved. +After saving the history, the history file is truncated +to contain no more than @env{$HISTFILESIZE} lines. +If @env{HISTFILESIZE} is unset, or set to null, a non-numeric value, or +a numeric value less than zero, the history file is not truncated. + +If the @env{HISTTIMEFORMAT} is set, the time stamp information +associated with each history entry is written to the history file, +marked with the history comment character. +When the history file is read, lines beginning with the history +comment character followed immediately by a digit are interpreted +as timestamps for the following history entry. + +The builtin command @code{fc} may be used to list or edit and re-execute +a portion of the history list. +The @code{history} builtin may be used to display or modify the history +list and manipulate the history file. +When using command-line editing, search commands +are available in each editing mode that provide access to the +history list (@pxref{Commands For History}). + +The shell allows control over which commands are saved on the history +list. The @env{HISTCONTROL} and @env{HISTIGNORE} +variables may be set to cause the shell to save only a subset of the +commands entered. +The @code{cmdhist} +shell option, if enabled, causes the shell to attempt to save each +line of a multi-line command in the same history entry, adding +semicolons where necessary to preserve syntactic correctness. +The @code{lithist} +shell option causes the shell to save the command with embedded newlines +instead of semicolons. +The @code{shopt} builtin is used to set these options. +@xref{The Shopt Builtin}, for a description of @code{shopt}. + +@node Bash History Builtins +@section Bash History Builtins +@cindex history builtins + +Bash provides two builtin commands which manipulate the +history list and history file. + +@table @code + +@item fc +@btindex fc +@example +@code{fc [-e @var{ename}] [-lnr] [@var{first}] [@var{last}]} +@code{fc -s [@var{pat}=@var{rep}] [@var{command}]} +@end example + +The first form selects a range of commands from @var{first} to +@var{last} from the history list and displays or edits and re-executes +them. +Both @var{first} and +@var{last} may be specified as a string (to locate the most recent +command beginning with that string) or as a number (an index into the +history list, where a negative number is used as an offset from the +current command number). + +When listing, a @var{first} or @var{last} of 0 is equivalent to -1 +and -0 is equivalent to the current command (usually the @code{fc} +command); +otherwise 0 is equivalent to -1 and -0 is invalid. + +If @var{last} is not specified, it is set to +@var{first}. If @var{first} is not specified, it is set to the previous +command for editing and @minus{}16 for listing. If the @option{-l} flag is +given, the commands are listed on standard output. The @option{-n} flag +suppresses the command numbers when listing. The @option{-r} flag +reverses the order of the listing. Otherwise, the editor given by +@var{ename} is invoked on a file containing those commands. If +@var{ename} is not given, the value of the following variable expansion +is used: @code{$@{FCEDIT:-$@{EDITOR:-vi@}@}}. This says to use the +value of the @env{FCEDIT} variable if set, or the value of the +@env{EDITOR} variable if that is set, or @code{vi} if neither is set. +When editing is complete, the edited commands are echoed and executed. + +In the second form, @var{command} is re-executed after each instance +of @var{pat} in the selected command is replaced by @var{rep}. +@var{command} is interpreted the same as @var{first} above. + +A useful alias to use with the @code{fc} command is @code{r='fc -s'}, so +that typing @samp{r cc} runs the last command beginning with @code{cc} +and typing @samp{r} re-executes the last command (@pxref{Aliases}). + +@item history +@btindex history +@example +history [@var{n}] +history -c +history -d @var{offset} +history -d @var{start}-@var{end} +history [-anrw] [@var{filename}] +history -ps @var{arg} +@end example + +With no options, display the history list with line numbers. +Lines prefixed with a @samp{*} have been modified. +An argument of @var{n} lists only the last @var{n} lines. +If the shell variable @env{HISTTIMEFORMAT} is set and not null, +it is used as a format string for @var{strftime} to display +the time stamp associated with each displayed history entry. +No intervening blank is printed between the formatted time stamp +and the history line. + +Options, if supplied, have the following meanings: + +@table @code +@item -c +Clear the history list. This may be combined +with the other options to replace the history list completely. + +@item -d @var{offset} +Delete the history entry at position @var{offset}. +If @var{offset} is positive, it should be specified as it appears when +the history is displayed. +If @var{offset} is negative, it is interpreted as relative to one greater +than the last history position, so negative indices count back from the +end of the history, and an index of @samp{-1} refers to the current +@code{history -d} command. + +@item -d @var{start}-@var{end} +Delete the history entries between positions @var{start} and @var{end}, +inclusive. Positive and negative values for @var{start} and @var{end} +are interpreted as described above. + +@item -a +Append the new history lines to the history file. +These are history lines entered since the beginning of the current +Bash session, but not already appended to the history file. + +@item -n +Append the history lines not already read from the history file +to the current history list. These are lines appended to the history +file since the beginning of the current Bash session. + +@item -r +Read the history file and append its contents to +the history list. + +@item -w +Write out the current history list to the history file. + +@item -p +Perform history substitution on the @var{arg}s and display the result +on the standard output, without storing the results in the history list. + +@item -s +The @var{arg}s are added to the end of +the history list as a single entry. + +@end table + +When any of the @option{-w}, @option{-r}, @option{-a}, or @option{-n} options is +used, if @var{filename} +is given, then it is used as the history file. If not, then +the value of the @env{HISTFILE} variable is used. + +@end table +@end ifset + +@node History Interaction +@section History Expansion +@cindex history expansion + +The History library provides a history expansion feature that is similar +to the history expansion provided by @code{csh}. This section +describes the syntax used to manipulate the history information. + +History expansions introduce words from the history list into +the input stream, making it easy to repeat commands, insert the +arguments to a previous command into the current input line, or +fix errors in previous commands quickly. + +@ifset BashFeatures +History expansion is performed immediately after a complete line +is read, before the shell breaks it into words, and is performed +on each line individually. Bash attempts to inform the history +expansion functions about quoting still in effect from previous lines. +@end ifset + +History expansion takes place in two parts. The first is to determine +which line from the history list should be used during substitution. +The second is to select portions of that line for inclusion into the +current one. The line selected from the history is called the +@dfn{event}, and the portions of that line that are acted upon are +called @dfn{words}. Various @dfn{modifiers} are available to manipulate +the selected words. The line is broken into words in the same fashion +that Bash does, so that several words +surrounded by quotes are considered one word. +History expansions are introduced by the appearance of the +history expansion character, which is @samp{!} by default. + +History expansion implements shell-like quoting conventions: +a backslash can be used to remove the special handling for the next character; +single quotes enclose verbatim sequences of characters, and can be used to +inhibit history expansion; +and characters enclosed within double quotes may be subject to history +expansion, since backslash can escape the history expansion character, +but single quotes may not, since they are not treated specially within +double quotes. + +@ifset BashFeatures +When using the shell, only @samp{\} and @samp{'} may be used to escape the +history expansion character, but the history expansion character is +also treated as quoted if it immediately precedes the closing double quote +in a double-quoted string. +@end ifset + +@ifset BashFeatures +Several shell options settable with the @code{shopt} +builtin (@pxref{The Shopt Builtin}) may be used to tailor +the behavior of history expansion. If the +@code{histverify} shell option is enabled, and Readline +is being used, history substitutions are not immediately passed to +the shell parser. +Instead, the expanded line is reloaded into the Readline +editing buffer for further modification. +If Readline is being used, and the @code{histreedit} +shell option is enabled, a failed history expansion will be +reloaded into the Readline editing buffer for correction. +The @option{-p} option to the @code{history} builtin command +may be used to see what a history expansion will do before using it. +The @option{-s} option to the @code{history} builtin may be used to +add commands to the end of the history list without actually executing +them, so that they are available for subsequent recall. +This is most useful in conjunction with Readline. + +The shell allows control of the various characters used by the +history expansion mechanism with the @code{histchars} variable, +as explained above (@pxref{Bash Variables}). The shell uses +the history comment character to mark history timestamps when +writing the history file. +@end ifset + +@menu +* Event Designators:: How to specify which history line to use. +* Word Designators:: Specifying which words are of interest. +* Modifiers:: Modifying the results of substitution. +@end menu + +@node Event Designators +@subsection Event Designators +@cindex event designators + +An event designator is a reference to a command line entry in the +history list. +Unless the reference is absolute, events are relative to the current +position in the history list. +@cindex history events + +@table @asis + +@item @code{!} +@ifset BashFeatures +Start a history substitution, except when followed by a space, tab, +the end of the line, @samp{=} or @samp{(} (when the +@code{extglob} shell option is enabled using the @code{shopt} builtin). +@end ifset +@ifclear BashFeatures +Start a history substitution, except when followed by a space, tab, +the end of the line, or @samp{=}. +@end ifclear + +@item @code{!@var{n}} +Refer to command line @var{n}. + +@item @code{!-@var{n}} +Refer to the command @var{n} lines back. + +@item @code{!!} +Refer to the previous command. This is a synonym for @samp{!-1}. + +@item @code{!@var{string}} +Refer to the most recent command +preceding the current position in the history list +starting with @var{string}. + +@item @code{!?@var{string}[?]} +Refer to the most recent command +preceding the current position in the history list +containing @var{string}. +The trailing +@samp{?} may be omitted if the @var{string} is followed immediately by +a newline. +If @var{string} is missing, the string from the most recent search is used; +it is an error if there is no previous search string. + +@item @code{^@var{string1}^@var{string2}^} +Quick Substitution. Repeat the last command, replacing @var{string1} +with @var{string2}. Equivalent to +@code{!!:s^@var{string1}^@var{string2}^}. + +@item @code{!#} +The entire command line typed so far. + +@end table + +@node Word Designators +@subsection Word Designators + +Word designators are used to select desired words from the event. +A @samp{:} separates the event specification from the word designator. It +may be omitted if the word designator begins with a @samp{^}, @samp{$}, +@samp{*}, @samp{-}, or @samp{%}. Words are numbered from the beginning +of the line, with the first word being denoted by 0 (zero). Words are +inserted into the current line separated by single spaces. + +@need 0.75 +For example, + +@table @code +@item !! +designates the preceding command. When you type this, the preceding +command is repeated in toto. + +@item !!:$ +designates the last argument of the preceding command. This may be +shortened to @code{!$}. + +@item !fi:2 +designates the second argument of the most recent command starting with +the letters @code{fi}. +@end table + +@need 0.75 +Here are the word designators: + +@table @code + +@item 0 (zero) +The @code{0}th word. For many applications, this is the command word. + +@item @var{n} +The @var{n}th word. + +@item ^ +The first argument; that is, word 1. + +@item $ +The last argument. + +@item % +The first word matched by the most recent @samp{?@var{string}?} search, +if the search string begins with a character that is part of a word. + +@item @var{x}-@var{y} +A range of words; @samp{-@var{y}} abbreviates @samp{0-@var{y}}. + +@item * +All of the words, except the @code{0}th. This is a synonym for @samp{1-$}. +It is not an error to use @samp{*} if there is just one word in the event; +the empty string is returned in that case. + +@item @var{x}* +Abbreviates @samp{@var{x}-$} + +@item @var{x}- +Abbreviates @samp{@var{x}-$} like @samp{@var{x}*}, but omits the last word. +If @samp{x} is missing, it defaults to 0. + +@end table + +If a word designator is supplied without an event specification, the +previous command is used as the event. + +@node Modifiers +@subsection Modifiers + +After the optional word designator, you can add a sequence of one or more +of the following modifiers, each preceded by a @samp{:}. +These modify, or edit, the word or words selected from the history event. + +@table @code + +@item h +Remove a trailing pathname component, leaving only the head. + +@item t +Remove all leading pathname components, leaving the tail. + +@item r +Remove a trailing suffix of the form @samp{.@var{suffix}}, leaving +the basename. + +@item e +Remove all but the trailing suffix. + +@item p +Print the new command but do not execute it. + +@ifset BashFeatures +@item q +Quote the substituted words, escaping further substitutions. + +@item x +Quote the substituted words as with @samp{q}, +but break into words at spaces, tabs, and newlines. +The @samp{q} and @samp{x} modifiers are mutually exclusive; the last one +supplied is used. +@end ifset + +@item s/@var{old}/@var{new}/ +Substitute @var{new} for the first occurrence of @var{old} in the +event line. +Any character may be used as the delimiter in place of @samp{/}. +The delimiter may be quoted in @var{old} and @var{new} +with a single backslash. If @samp{&} appears in @var{new}, +it is replaced by @var{old}. A single backslash will quote +the @samp{&}. +If @var{old} is null, it is set to the last @var{old} +substituted, or, if no previous history substitutions took place, +the last @var{string} +in a !?@var{string}@code{[?]} +search. +If @var{new} is is null, each matching @var{old} is deleted. +The final delimiter is optional if it is the last +character on the input line. + +@item & +Repeat the previous substitution. + +@item g +@itemx a +Cause changes to be applied over the entire event line. Used in +conjunction with @samp{s}, as in @code{gs/@var{old}/@var{new}/}, +or with @samp{&}. + +@item G +Apply the following @samp{s} or @samp{&} modifier once to each word +in the event. + +@end table |