rluser.texinfo

这个是LINUX下的GDB调度工具的源码

Lines beginning with a @samp{$} indicate conditional
constructs (@pxref{Conditional Init Constructs}).  Other lines
denote variable settings and key bindings.

@table @asis
@item Variable Settings
You can modify the run-time behavior of Readline by
altering the values of variables in Readline
using the @code{set} command within the init file.
The syntax is simple:

@example
set @var{variable} @var{value}
@end example

@noindent
Here, for example, is how to
change from the default Emacs-like key binding to use
@code{vi} line editing commands:

@example
set editing-mode vi
@end example

Variable names and values, where appropriate, are recognized without regard
to case. 

@ifset BashFeatures
The @w{@code{bind -V}} command lists the current Readline variable names
and values.  @xref{Bash Builtins}.
@end ifset

A great deal of run-time behavior is changeable with the following
variables.

@cindex variables, readline
@table @code

@item bell-style
@vindex bell-style
Controls what happens when Readline wants to ring the terminal bell.
If set to @samp{none}, Readline never rings the bell.  If set to
@samp{visible}, Readline uses a visible bell if one is available.
If set to @samp{audible} (the default), Readline attempts to ring
the terminal's bell.

@item comment-begin
@vindex comment-begin
The string to insert at the beginning of the line when the
@code{insert-comment} command is executed.  The default value
is @code{"#"}.

@item completion-ignore-case
If set to @samp{on}, Readline performs filename matching and completion
in a case-insensitive fashion.
The default value is @samp{off}.

@item completion-query-items
@vindex completion-query-items
The number of possible completions that determines when the user is
asked whether he wants to see the list of possibilities.  If the
number of possible completions is greater than this value,
Readline will ask the user whether or not he wishes to view
them; otherwise, they are simply listed.
This variable must be set to an integer value greater than or equal to 0.
The default limit is @code{100}.

@item convert-meta
@vindex convert-meta
If set to @samp{on}, Readline will convert characters with the
eighth bit set to an @sc{ascii} key sequence by stripping the eighth
bit and prefixing an @key{ESC} character, converting them to a
meta-prefixed key sequence.  The default value is @samp{on}.

@item disable-completion
@vindex disable-completion
If set to @samp{On}, Readline will inhibit word completion.
Completion  characters will be inserted into the line as if they had
been mapped to @code{self-insert}.  The default is @samp{off}.

@item editing-mode
@vindex editing-mode
The @code{editing-mode} variable controls which default set of
key bindings is used.  By default, Readline starts up in Emacs editing
mode, where the keystrokes are most similar to Emacs.  This variable can be
set to either @samp{emacs} or @samp{vi}.

@item enable-keypad
@vindex enable-keypad
When set to @samp{on}, Readline will try to enable the application
keypad when it is called.  Some systems need this to enable the
arrow keys.  The default is @samp{off}.

@item expand-tilde
@vindex expand-tilde
If set to @samp{on}, tilde expansion is performed when Readline
attempts word completion.  The default is @samp{off}.

@vindex history-preserve-point
If set to @samp{on}, the history code attempts to place point at the
same location on each history line retrived with @code{previous-history}
or @code{next-history}.

@item horizontal-scroll-mode
@vindex horizontal-scroll-mode
This variable can be set to either @samp{on} or @samp{off}.  Setting it
to @samp{on} means that the text of the lines being edited will scroll
horizontally on a single screen line when they are longer than the width
of the screen, instead of wrapping onto a new screen line.  By default,
this variable is set to @samp{off}.

@item input-meta
@vindex input-meta
@vindex meta-flag
If set to @samp{on}, Readline will enable eight-bit input (it
will not clear the eighth bit in the characters it reads),
regardless of what the terminal claims it can support.  The
default value is @samp{off}.  The name @code{meta-flag} is a
synonym for this variable.

@item isearch-terminators
@vindex isearch-terminators
The string of characters that should terminate an incremental search without
subsequently executing the character as a command (@pxref{Searching}).
If this variable has not been given a value, the characters @key{ESC} and
@kbd{C-J} will terminate an incremental search.

@item keymap
@vindex keymap
Sets Readline's idea of the current keymap for key binding commands.
Acceptable @code{keymap} names are
@code{emacs},
@code{emacs-standard},
@code{emacs-meta},
@code{emacs-ctlx},
@code{vi},
@code{vi-move},
@code{vi-command}, and
@code{vi-insert}.
@code{vi} is equivalent to @code{vi-command}; @code{emacs} is
equivalent to @code{emacs-standard}.  The default value is @code{emacs}.
The value of the @code{editing-mode} variable also affects the
default keymap.

@item mark-directories
If set to @samp{on}, completed directory names have a slash
appended.  The default is @samp{on}.

@item mark-modified-lines
@vindex mark-modified-lines
This variable, when set to @samp{on}, causes Readline to display an
asterisk (@samp{*}) at the start of history lines which have been modified.
This variable is @samp{off} by default.

@item mark-symlinked-directories
@vindex mark-symlinked-directories
If set to @samp{on}, completed names which are symbolic links
to directories have a slash appended (subject to the value of
@code{mark-directories}).
The default is @samp{off}.

@item match-hidden-files
@vindex match-hidden-files
This variable, when set to @samp{on}, causes Readline to match files whose
names begin with a @samp{.} (hidden files) when performing filename
completion, unless the leading @samp{.} is
supplied by the user in the filename to be completed.
This variable is @samp{on} by default.

@item output-meta
@vindex output-meta
If set to @samp{on}, Readline will display characters with the
eighth bit set directly rather than as a meta-prefixed escape
sequence.  The default is @samp{off}.

@item page-completions
@vindex page-completions
If set to @samp{on}, Readline uses an internal @code{more}-like pager
to display a screenful of possible completions at a time.
This variable is @samp{on} by default.

@item print-completions-horizontally
If set to @samp{on}, Readline will display completions with matches
sorted horizontally in alphabetical order, rather than down the screen.
The default is @samp{off}.

@item show-all-if-ambiguous
@vindex show-all-if-ambiguous
This alters the default behavior of the completion functions.  If
set to @samp{on}, 
words which have more than one possible completion cause the
matches to be listed immediately instead of ringing the bell.
The default value is @samp{off}.

@item visible-stats
@vindex visible-stats
If set to @samp{on}, a character denoting a file's type
is appended to the filename when listing possible
completions.  The default is @samp{off}.

@end table

@item Key Bindings
The syntax for controlling key bindings in the init file is
simple.  First you need to find the name of the command that you
want to change.  The following sections contain tables of the command
name, the default keybinding, if any, and a short description of what
the command does.

Once you know the name of the command, simply place on a line
in the init file the name of the key
you wish to bind the command to, a colon, and then the name of the
command.  The name of the key
can be expressed in different ways, depending on what you find most
comfortable.

In addition to command names, readline allows keys to be bound
to a string that is inserted when the key is pressed (a @var{macro}).

@ifset BashFeatures
The @w{@code{bind -p}} command displays Readline function names and
bindings in a format that can put directly into an initialization file.
@xref{Bash Builtins}.
@end ifset

@table @asis
@item @w{@var{keyname}: @var{function-name} or @var{macro}}
@var{keyname} is the name of a key spelled out in English.  For example:
@example
Control-u: universal-argument
Meta-Rubout: backward-kill-word
Control-o: "> output"
@end example

In the above example, @kbd{C-u} is bound to the function
@code{universal-argument},
@kbd{M-DEL} is bound to the function @code{backward-kill-word}, and
@kbd{C-o} is bound to run the macro
expressed on the right hand side (that is, to insert the text
@samp{> output} into the line).

A number of symbolic character names are recognized while
processing this key binding syntax:
@var{DEL},
@var{ESC},
@var{ESCAPE},
@var{LFD},
@var{NEWLINE},
@var{RET},
@var{RETURN},
@var{RUBOUT},
@var{SPACE},
@var{SPC},
and
@var{TAB}.

@item @w{"@var{keyseq}": @var{function-name} or @var{macro}}
@var{keyseq} differs from @var{keyname} above in that strings
denoting an entire key sequence can be specified, by placing
the key sequence in double quotes.  Some @sc{gnu} Emacs style key
escapes can be used, as in the following example, but the
special character names are not recognized.

@example
"\C-u": universal-argument
"\C-x\C-r": re-read-init-file
"\e[11~": "Function Key 1"
@end example

In the above example, @kbd{C-u} is again bound to the function
@code{universal-argument} (just as it was in the first example),
@samp{@kbd{C-x} @kbd{C-r}} is bound to the function @code{re-read-init-file},
and @samp{@key{ESC} @key{[} @key{1} @key{1} @key{~}} is bound to insert
the text @samp{Function Key 1}.

@end table

The following @sc{gnu} Emacs style escape sequences are available when
specifying key sequences:

@table @code
@item @kbd{\C-}
control prefix
@item @kbd{\M-}
meta prefix
@item @kbd{\e}
an escape character
@item @kbd{\\}
backslash
@item @kbd{\"}
@key{"}, a double quotation mark
@item @kbd{\'}
@key{'}, a single quote or apostrophe
@end table

In addition to the @sc{gnu} Emacs style escape sequences, a second
set of backslash escapes is available:

@table @code
@item \a
alert (bell)
@item \b
backspace
@item \d
delete
@item \f
form feed
@item \n
newline
@item \r
carriage return
@item \t
horizontal tab
@item \v
vertical tab
@item \@var{nnn}
the eight-bit character whose value is the octal value @var{nnn}
(one to three digits)
@item \x@var{HH}
the eight-bit character whose value is the hexadecimal value @var{HH}
(one or two hex digits)
@end table

When entering the text of a macro, single or double quotes must
be used to indicate a macro definition.
Unquoted text is assumed to be a function name.
In the macro body, the backslash escapes described above are expanded.
Backslash will quote any other character in the macro text,
including @samp{"} and @samp{'}.
For example, the following binding will make @samp{@kbd{C-x} \}
insert a single @samp{\} into the line:
@example
"\C-x\\": "\\"
@end example

@end table

@node Conditional Init Constructs
@subsection Conditional Init Constructs

Readline implements a facility similar in spirit to the conditional
compilation features of the C preprocessor which allows key
bindings and variable settings to be performed as the result
of tests.  There are four parser directives used.

@table @code
@item $if
The @code{$if} construct allows bindings to be made based on the
editing mode, the terminal being used, or the application using
Readline.  The text of the test extends to the end of the line;
no characters are required to isolate it.

@table @code
@item mode
The @code{mode=} form of the @code{$if} directive is used to test
whether Readline is in @code{emacs} or @code{vi} mode.
This may be used in conjunction
with the @samp{set keymap} command, for instance, to set bindings in
the @code{emacs-standard} and @code{emacs-ctlx} keymaps only if
Readline is starting out in @code{emacs} mode.