hsuser.texi

linux中bash shell的源代码

@ignore
This file documents the user interface to the GNU History library.

Copyright (C) 1988-2002 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 an interactive shell 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 not set, no truncation is performed.

If the @env{HISTTIMEFORMAT} is set, the time stamp information
associated with each history entry is written to the history file.

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{Bash Builtins}, 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}] [-nlr] [@var{first}] [@var{last}]}
@code{fc -s [@var{pat}=@var{rep}] [@var{command}]}
@end example

Fix Command.  In the first form, a range of commands from @var{first} to
@var{last} is selected from the history list.  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).  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}.

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 [-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}.
@var{offset} should be specified as it appears when the history is
displayed.

@item -a
Append the new
history lines (history lines entered since the beginning of the
current Bash session) 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 current history file and append its contents to
the history list.

@item -w
Write out the current history 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