458 lines
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458 lines
15 KiB
Plaintext
@ignore
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This file documents the user interface to the GNU History library.
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Copyright (C) 1988-2002 Free Software Foundation, Inc.
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Authored by Brian Fox and Chet Ramey.
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Permission is granted to make and distribute verbatim copies of this manual
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provided the copyright notice and this permission notice are preserved on
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all copies.
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Permission is granted to process this file through Tex and print the
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results, provided the printed document carries copying permission notice
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identical to this one except for the removal of this paragraph (this
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paragraph not being relevant to the printed manual).
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Permission is granted to copy and distribute modified versions of this
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manual under the conditions for verbatim copying, provided also that the
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GNU Copyright statement is available to the distributee, and provided that
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the entire resulting derived work is distributed under the terms of a
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permission notice identical to this one.
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Permission is granted to copy and distribute translations of this manual
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into another language, under the above conditions for modified versions.
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@end ignore
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@node Using History Interactively
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@chapter Using History Interactively
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@ifclear BashFeatures
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@defcodeindex bt
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@end ifclear
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@ifset BashFeatures
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This chapter describes how to use the @sc{gnu} History Library
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interactively, from a user's standpoint.
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It should be considered a user's guide.
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For information on using the @sc{gnu} History Library in other programs,
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see the @sc{gnu} Readline Library Manual.
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@end ifset
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@ifclear BashFeatures
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This chapter describes how to use the @sc{gnu} History Library interactively,
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from a user's standpoint. It should be considered a user's guide. For
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information on using the @sc{gnu} History Library in your own programs,
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@pxref{Programming with GNU History}.
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@end ifclear
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@ifset BashFeatures
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@menu
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* Bash History Facilities:: How Bash lets you manipulate your command
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history.
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* Bash History Builtins:: The Bash builtin commands that manipulate
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the command history.
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* History Interaction:: What it feels like using History as a user.
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@end menu
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@end ifset
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@ifclear BashFeatures
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@menu
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* History Interaction:: What it feels like using History as a user.
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@end menu
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@end ifclear
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@ifset BashFeatures
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@node Bash History Facilities
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@section Bash History Facilities
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@cindex command history
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@cindex history list
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When the @option{-o history} option to the @code{set} builtin
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is enabled (@pxref{The Set Builtin}),
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the shell provides access to the @dfn{command history},
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the list of commands previously typed.
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The value of the @env{HISTSIZE} shell variable is used as the
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number of commands to save in a history list.
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The text of the last @env{$HISTSIZE}
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commands (default 500) is saved.
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The shell stores each command in the history list prior to
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parameter and variable expansion
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but after history expansion is performed, subject to the
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values of the shell variables
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@env{HISTIGNORE} and @env{HISTCONTROL}.
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When the shell starts up, the history is initialized from the
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file named by the @env{HISTFILE} variable (default @file{~/.bash_history}).
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The file named by the value of @env{HISTFILE} is truncated, if
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necessary, to contain no more than the number of lines specified by
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the value of the @env{HISTFILESIZE} variable.
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When an interactive shell exits, the last
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@env{$HISTSIZE} lines are copied from the history list to the file
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named by @env{$HISTFILE}.
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If the @code{histappend} shell option is set (@pxref{Bash Builtins}),
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the lines are appended to the history file,
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otherwise the history file is overwritten.
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If @env{HISTFILE}
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is unset, or if the history file is unwritable, the history is
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not saved. After saving the history, the history file is truncated
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to contain no more than @env{$HISTFILESIZE}
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lines. If @env{HISTFILESIZE} is not set, no truncation is performed.
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If the @env{HISTTIMEFORMAT} is set, the time stamp information
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associated with each history entry is written to the history file.
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The builtin command @code{fc} may be used to list or edit and re-execute
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a portion of the history list.
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The @code{history} builtin may be used to display or modify the history
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list and manipulate the history file.
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When using command-line editing, search commands
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are available in each editing mode that provide access to the
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history list (@pxref{Commands For History}).
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The shell allows control over which commands are saved on the history
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list. The @env{HISTCONTROL} and @env{HISTIGNORE}
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variables may be set to cause the shell to save only a subset of the
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commands entered.
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The @code{cmdhist}
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shell option, if enabled, causes the shell to attempt to save each
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line of a multi-line command in the same history entry, adding
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semicolons where necessary to preserve syntactic correctness.
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The @code{lithist}
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shell option causes the shell to save the command with embedded newlines
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instead of semicolons.
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The @code{shopt} builtin is used to set these options.
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@xref{Bash Builtins}, for a description of @code{shopt}.
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@node Bash History Builtins
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@section Bash History Builtins
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@cindex history builtins
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Bash provides two builtin commands which manipulate the
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history list and history file.
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@table @code
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@item fc
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@btindex fc
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@example
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@code{fc [-e @var{ename}] [-nlr] [@var{first}] [@var{last}]}
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@code{fc -s [@var{pat}=@var{rep}] [@var{command}]}
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@end example
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Fix Command. In the first form, a range of commands from @var{first} to
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@var{last} is selected from the history list. Both @var{first} and
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@var{last} may be specified as a string (to locate the most recent
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command beginning with that string) or as a number (an index into the
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history list, where a negative number is used as an offset from the
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current command number). If @var{last} is not specified it is set to
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@var{first}. If @var{first} is not specified it is set to the previous
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command for editing and @minus{}16 for listing. If the @option{-l} flag is
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given, the commands are listed on standard output. The @option{-n} flag
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suppresses the command numbers when listing. The @option{-r} flag
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reverses the order of the listing. Otherwise, the editor given by
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@var{ename} is invoked on a file containing those commands. If
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@var{ename} is not given, the value of the following variable expansion
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is used: @code{$@{FCEDIT:-$@{EDITOR:-vi@}@}}. This says to use the
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value of the @env{FCEDIT} variable if set, or the value of the
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@env{EDITOR} variable if that is set, or @code{vi} if neither is set.
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When editing is complete, the edited commands are echoed and executed.
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In the second form, @var{command} is re-executed after each instance
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of @var{pat} in the selected command is replaced by @var{rep}.
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A useful alias to use with the @code{fc} command is @code{r='fc -s'}, so
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that typing @samp{r cc} runs the last command beginning with @code{cc}
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and typing @samp{r} re-executes the last command (@pxref{Aliases}).
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@item history
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@btindex history
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@example
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history [@var{n}]
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history -c
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history -d @var{offset}
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history [-anrw] [@var{filename}]
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history -ps @var{arg}
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@end example
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With no options, display the history list with line numbers.
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Lines prefixed with a @samp{*} have been modified.
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An argument of @var{n} lists only the last @var{n} lines.
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If the shell variable @env{HISTTIMEFORMAT} is set and not null,
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it is used as a format string for @var{strftime} to display
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the time stamp associated with each displayed history entry.
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No intervening blank is printed between the formatted time stamp
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and the history line.
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Options, if supplied, have the following meanings:
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@table @code
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@item -c
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Clear the history list. This may be combined
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with the other options to replace the history list completely.
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@item -d @var{offset}
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Delete the history entry at position @var{offset}.
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@var{offset} should be specified as it appears when the history is
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displayed.
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@item -a
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Append the new
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history lines (history lines entered since the beginning of the
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current Bash session) to the history file.
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@item -n
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Append the history lines not already read from the history file
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to the current history list. These are lines appended to the history
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file since the beginning of the current Bash session.
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@item -r
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Read the current history file and append its contents to
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the history list.
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@item -w
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Write out the current history to the history file.
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@item -p
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Perform history substitution on the @var{arg}s and display the result
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on the standard output, without storing the results in the history list.
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@item -s
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The @var{arg}s are added to the end of
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the history list as a single entry.
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@end table
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When any of the @option{-w}, @option{-r}, @option{-a}, or @option{-n} options is
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used, if @var{filename}
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is given, then it is used as the history file. If not, then
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the value of the @env{HISTFILE} variable is used.
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@end table
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@end ifset
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@node History Interaction
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@section History Expansion
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@cindex history expansion
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The History library provides a history expansion feature that is similar
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to the history expansion provided by @code{csh}. This section
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describes the syntax used to manipulate the history information.
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History expansions introduce words from the history list into
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the input stream, making it easy to repeat commands, insert the
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arguments to a previous command into the current input line, or
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fix errors in previous commands quickly.
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History expansion takes place in two parts. The first is to determine
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which line from the history list should be used during substitution.
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The second is to select portions of that line for inclusion into the
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current one. The line selected from the history is called the
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@dfn{event}, and the portions of that line that are acted upon are
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called @dfn{words}. Various @dfn{modifiers} are available to manipulate
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the selected words. The line is broken into words in the same fashion
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that Bash does, so that several words
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surrounded by quotes are considered one word.
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History expansions are introduced by the appearance of the
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history expansion character, which is @samp{!} by default.
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@ifset BashFeatures
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Only @samp{\} and @samp{'} may be used to escape the history expansion
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character.
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@end ifset
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@ifset BashFeatures
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Several shell options settable with the @code{shopt}
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builtin (@pxref{Bash Builtins}) may be used to tailor
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the behavior of history expansion. If the
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@code{histverify} shell option is enabled, and Readline
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is being used, history substitutions are not immediately passed to
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the shell parser.
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Instead, the expanded line is reloaded into the Readline
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editing buffer for further modification.
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If Readline is being used, and the @code{histreedit}
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shell option is enabled, a failed history expansion will be
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reloaded into the Readline editing buffer for correction.
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The @option{-p} option to the @code{history} builtin command
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may be used to see what a history expansion will do before using it.
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The @option{-s} option to the @code{history} builtin may be used to
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add commands to the end of the history list without actually executing
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them, so that they are available for subsequent recall.
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This is most useful in conjunction with Readline.
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The shell allows control of the various characters used by the
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history expansion mechanism with the @code{histchars} variable.
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@end ifset
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@menu
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* Event Designators:: How to specify which history line to use.
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* Word Designators:: Specifying which words are of interest.
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* Modifiers:: Modifying the results of substitution.
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@end menu
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@node Event Designators
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@subsection Event Designators
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@cindex event designators
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An event designator is a reference to a command line entry in the
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history list.
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@cindex history events
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@table @asis
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@item @code{!}
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@ifset BashFeatures
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Start a history substitution, except when followed by a space, tab,
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the end of the line, @samp{=} or @samp{(} (when the
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@code{extglob} shell option is enabled using the @code{shopt} builtin).
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@end ifset
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@ifclear BashFeatures
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Start a history substitution, except when followed by a space, tab,
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the end of the line, or @samp{=}.
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@end ifclear
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@item @code{!@var{n}}
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Refer to command line @var{n}.
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@item @code{!-@var{n}}
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Refer to the command @var{n} lines back.
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@item @code{!!}
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Refer to the previous command. This is a synonym for @samp{!-1}.
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@item @code{!@var{string}}
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Refer to the most recent command starting with @var{string}.
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@item @code{!?@var{string}[?]}
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Refer to the most recent command containing @var{string}. The trailing
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@samp{?} may be omitted if the @var{string} is followed immediately by
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a newline.
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@item @code{^@var{string1}^@var{string2}^}
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Quick Substitution. Repeat the last command, replacing @var{string1}
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with @var{string2}. Equivalent to
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@code{!!:s/@var{string1}/@var{string2}/}.
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@item @code{!#}
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The entire command line typed so far.
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@end table
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@node Word Designators
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@subsection Word Designators
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Word designators are used to select desired words from the event.
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A @samp{:} separates the event specification from the word designator. It
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may be omitted if the word designator begins with a @samp{^}, @samp{$},
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@samp{*}, @samp{-}, or @samp{%}. Words are numbered from the beginning
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of the line, with the first word being denoted by 0 (zero). Words are
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inserted into the current line separated by single spaces.
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@need 0.75
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For example,
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@table @code
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@item !!
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designates the preceding command. When you type this, the preceding
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command is repeated in toto.
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@item !!:$
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designates the last argument of the preceding command. This may be
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shortened to @code{!$}.
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@item !fi:2
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designates the second argument of the most recent command starting with
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the letters @code{fi}.
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@end table
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@need 0.75
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Here are the word designators:
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@table @code
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@item 0 (zero)
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The @code{0}th word. For many applications, this is the command word.
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@item @var{n}
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The @var{n}th word.
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@item ^
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The first argument; that is, word 1.
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@item $
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The last argument.
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@item %
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The word matched by the most recent @samp{?@var{string}?} search.
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@item @var{x}-@var{y}
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A range of words; @samp{-@var{y}} abbreviates @samp{0-@var{y}}.
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@item *
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All of the words, except the @code{0}th. This is a synonym for @samp{1-$}.
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It is not an error to use @samp{*} if there is just one word in the event;
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the empty string is returned in that case.
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@item @var{x}*
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Abbreviates @samp{@var{x}-$}
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@item @var{x}-
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Abbreviates @samp{@var{x}-$} like @samp{@var{x}*}, but omits the last word.
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@end table
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If a word designator is supplied without an event specification, the
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previous command is used as the event.
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@node Modifiers
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@subsection Modifiers
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After the optional word designator, you can add a sequence of one or more
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of the following modifiers, each preceded by a @samp{:}.
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@table @code
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@item h
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Remove a trailing pathname component, leaving only the head.
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@item t
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Remove all leading pathname components, leaving the tail.
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@item r
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Remove a trailing suffix of the form @samp{.@var{suffix}}, leaving
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the basename.
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@item e
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Remove all but the trailing suffix.
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@item p
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Print the new command but do not execute it.
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@ifset BashFeatures
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@item q
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Quote the substituted words, escaping further substitutions.
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@item x
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Quote the substituted words as with @samp{q},
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but break into words at spaces, tabs, and newlines.
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@end ifset
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@item s/@var{old}/@var{new}/
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Substitute @var{new} for the first occurrence of @var{old} in the
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event line. Any delimiter may be used in place of @samp{/}.
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The delimiter may be quoted in @var{old} and @var{new}
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with a single backslash. If @samp{&} appears in @var{new},
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it is replaced by @var{old}. A single backslash will quote
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the @samp{&}. The final delimiter is optional if it is the last
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character on the input line.
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@item &
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Repeat the previous substitution.
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@item g
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@itemx a
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Cause changes to be applied over the entire event line. Used in
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conjunction with @samp{s}, as in @code{gs/@var{old}/@var{new}/},
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or with @samp{&}.
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@item G
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Apply the following @samp{s} modifier once to each word in the event.
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@end table
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