readline.3

这个是LINUX下的GDB调度工具的源码

.\"
.\" MAN PAGE COMMENTS to
.\"
.\"	Chet Ramey
.\"	Information Network Services
.\"	Case Western Reserve University
.\"	[e-mail]
.\"
.\"	Last Change: Tue Jan 22 09:18:25 EST 2002
.\"
.TH READLINE 3 "2002 January 22" "GNU Readline 4.3"
.\"
.\" File Name macro.  This used to be `.PN', for Path Name,
.\" but Sun doesn't seem to like that very much.
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.de FN
\fI\|\\$1\|\fP
..
.SH NAME
readline \- get a line from a user with editing
.SH SYNOPSIS
.LP
.nf
.ft B
#include <stdio.h>
#include <readline/readline.h>
#include <readline/history.h>
.ft
.fi
.LP
.nf
\fIchar *\fP
.br
\fBreadline\fP (\fIconst char *prompt\fP);
.fi
.SH COPYRIGHT
.if n Readline is Copyright (C) 1989\-2002 by the Free Software Foundation, Inc.
.if t Readline is Copyright \(co 1989\-2002 by the Free Software Foundation, Inc.
.SH DESCRIPTION
.LP
.B readline
will read a line from the terminal
and return it, using
.B prompt
as a prompt.  If 
.B prompt
is \fBNULL\fP or the empty string, no prompt is issued.
The line returned is allocated with
.IR malloc (3);
the caller must free it when finished.  The line returned
has the final newline removed, so only the text of the line
remains.
.LP
.B readline
offers editing capabilities while the user is entering the
line.
By default, the line editing commands
are similar to those of emacs.
A vi\-style line editing interface is also available.
.LP
This manual page describes only the most basic use of \fBreadline\fP.
Much more functionality is available; see
\fIThe GNU Readline Library\fP and \fIThe GNU History Library\fP
for additional information.
.SH RETURN VALUE
.LP
.B readline
returns the text of the line read.  A blank line
returns the empty string.  If
.B EOF
is encountered while reading a line, and the line is empty,
.B NULL
is returned.  If an
.B EOF
is read with a non\-empty line, it is
treated as a newline.
.SH NOTATION
.LP
An emacs-style notation is used to denote
keystrokes.  Control keys are denoted by C\-\fIkey\fR, e.g., C\-n
means Control\-N.  Similarly, 
.I meta
keys are denoted by M\-\fIkey\fR, so M\-x means Meta\-X.  (On keyboards
without a 
.I meta
key, M\-\fIx\fP means ESC \fIx\fP, i.e., press the Escape key
then the
.I x
key.  This makes ESC the \fImeta prefix\fP.
The combination M\-C\-\fIx\fP means ESC\-Control\-\fIx\fP,
or press the Escape key
then hold the Control key while pressing the
.I x
key.)
.PP
Readline commands may be given numeric
.IR arguments ,
which normally act as a repeat count.  Sometimes, however, it is the
sign of the argument that is significant.  Passing a negative argument
to a command that acts in the forward direction (e.g., \fBkill\-line\fP)
causes that command to act in a backward direction.  Commands whose
behavior with arguments deviates from this are noted.
.PP
When a command is described as \fIkilling\fP text, the text
deleted is saved for possible future retrieval
(\fIyanking\fP).  The killed text is saved in a
\fIkill ring\fP.  Consecutive kills cause the text to be
accumulated into one unit, which can be yanked all at once. 
Commands which do not kill text separate the chunks of text
on the kill ring.
.SH INITIALIZATION FILE
.LP
Readline is customized by putting commands in an initialization
file (the \fIinputrc\fP file).
The name of this file is taken from the value of the
.B INPUTRC
environment variable.  If that variable is unset, the default is
.IR ~/.inputrc .
When a program which uses the readline library starts up, the
init file is read, and the key bindings and variables are set.
There are only a few basic constructs allowed in the
readline init file.  Blank lines are ignored.
Lines beginning with a \fB#\fP are comments.
Lines beginning with a \fB$\fP indicate conditional constructs.
Other lines denote key bindings and variable settings.
Each program using this library may add its own commands
and bindings.
.PP
For example, placing
.RS
.PP
M\-Control\-u: universal\-argument
.RE
or
.RS
C\-Meta\-u: universal\-argument
.RE
.sp
into the 
.I inputrc
would make M\-C\-u execute the readline command
.IR universal\-argument .
.PP
The following symbolic character names are recognized while
processing key bindings:
.IR DEL ,
.IR ESC ,
.IR ESCAPE ,
.IR LFD ,
.IR NEWLINE ,
.IR RET ,
.IR RETURN ,
.IR RUBOUT ,
.IR SPACE ,
.IR SPC ,
and
.IR TAB .
.PP
In addition to command names, readline allows keys to be bound
to a string that is inserted when the key is pressed (a \fImacro\fP).
.PP
.SS Key Bindings
.PP
The syntax for controlling key bindings in the
.I inputrc
file is simple.  All that is required is the name of the
command or the text of a macro and a key sequence to which
it should be bound. The name may be specified in one of two ways:
as a symbolic key name, possibly with \fIMeta\-\fP or \fIControl\-\fP
prefixes, or as a key sequence.
.PP
When using the form \fBkeyname\fP:\^\fIfunction-name\fP or \fImacro\fP,
.I keyname
is the name of a key spelled out in English.  For example:
.sp
.RS
Control\-u: universal\-argument
.br
Meta\-Rubout: backward\-kill\-word
.br
Control\-o: "> output"
.RE
.LP
In the above example,
.I C\-u
is bound to the function
.BR universal\-argument ,
.I M-DEL
is bound to the function
.BR backward\-kill\-word ,
and
.I C\-o
is bound to run the macro
expressed on the right hand side (that is, to insert the text
.if t \f(CW> output\fP
.if n ``> output''
into the line).
.PP
In the second form, \fB"keyseq"\fP:\^\fIfunction\-name\fP or \fImacro\fP,
.B keyseq
differs from
.B keyname
above in that strings denoting
an entire key sequence may be specified by placing the sequence
within double quotes.  Some GNU Emacs style key escapes can be
used, as in the following example, but the symbolic character names
are not recognized.
.sp
.RS
"\eC\-u": universal\-argument
.br
"\eC\-x\eC\-r": re\-read\-init\-file
.br
"\ee[11~": "Function Key 1"
.RE
.PP
In this example,
.I C-u
is again bound to the function
.BR universal\-argument .
.I "C-x C-r"
is bound to the function
.BR re\-read\-init\-file ,
and 
.I "ESC [ 1 1 ~"
is bound to insert the text
.if t \f(CWFunction Key 1\fP.
.if n ``Function Key 1''.
.PP
The full set of GNU Emacs style escape sequences available when specifying
key sequences is
.RS
.PD 0
.TP
.B \eC\-
control prefix
.TP
.B \eM\-
meta prefix
.TP
.B \ee
an escape character
.TP
.B \e\e
backslash
.TP
.B \e"
literal ", a double quote
.TP
.B \e'
literal ', a single quote
.RE
.PD
.PP
In addition to the GNU Emacs style escape sequences, a second
set of backslash escapes is available:
.RS
.PD 0
.TP
.B \ea
alert (bell)
.TP
.B \eb
backspace
.TP
.B \ed
delete
.TP
.B \ef
form feed
.TP
.B \en
newline
.TP
.B \er
carriage return
.TP
.B \et
horizontal tab
.TP
.B \ev
vertical tab
.TP
.B \e\fInnn\fP
the eight-bit character whose value is the octal value \fInnn\fP
(one to three digits)
.TP
.B \ex\fIHH\fP
the eight-bit character whose value is the hexadecimal value \fIHH\fP
(one or two hex digits)
.RE
.PD
.PP
When entering the text of a macro, single or double quotes should
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 " and '.
.PP
.B Bash
allows the current readline key bindings to be displayed or modified
with the
.B bind
builtin command.  The editing mode may be switched during interactive
use by using the
.B \-o
option to the
.B set
builtin command.  Other programs using this library provide
similar mechanisms.  The
.I inputrc
file may be edited and re-read if a program does not provide
any other means to incorporate new bindings.
.SS Variables
.PP
Readline has variables that can be used to further customize its
behavior.  A variable may be set in the
.I inputrc
file with a statement of the form
.RS
.PP
\fBset\fP \fIvariable\-name\fP \fIvalue\fP
.RE
.PP
Except where noted, readline variables can take the values
.B On
or
.B Off
(without regard to case).
The variables and their default values are:
.PP
.PD 0
.TP
.B bell\-style (audible)
Controls what happens when readline wants to ring the terminal bell.
If set to \fBnone\fP, readline never rings the bell.  If set to
\fBvisible\fP, readline uses a visible bell if one is available.
If set to \fBaudible\fP, readline attempts to ring the terminal's bell.
.TP
.B comment\-begin (``#'')
The string that is inserted in \fBvi\fP mode when the
.B insert\-comment
command is executed.
This command is bound to
.B M\-#
in emacs mode and to
.B #
in vi command mode.
.TP 
.B completion\-ignore\-case (Off)
If set to \fBOn\fP, readline performs filename matching and completion
in a case\-insensitive fashion.
.TP
.B completion\-query\-items (100)
This determines when the user is queried about viewing
the number of possible completions
generated by the \fBpossible\-completions\fP command.
It may be set to any integer value greater than or equal to
zero.  If the number of possible completions is greater than
or equal to the value of this variable, the user is asked whether
or not he wishes to view them; otherwise they are simply listed
on the terminal.
.TP
.B convert\-meta (On)
If set to \fBOn\fP, readline will convert characters with the
eighth bit set to an ASCII key sequence
by stripping the eighth bit and prefixing it with an
escape character (in effect, using escape as the \fImeta prefix\fP).
.TP
.B disable\-completion (Off)
If set to \fBOn\fP, readline will inhibit word completion.  Completion 
characters will be inserted into the line as if they had been
mapped to \fBself-insert\fP.
.TP
.B editing\-mode (emacs)
Controls whether readline begins with a set of key bindings similar
to emacs or vi.
.B editing\-mode
can be set to either
.B emacs
or
.BR vi .
.TP
.B enable\-keypad (Off)
When set to \fBOn\fP, readline will try to enable the application
keypad when it is called.  Some systems need this to enable the
arrow keys.
.TP
.B expand\-tilde (Off)
If set to \fBon\fP, tilde expansion is performed when readline
attempts word completion.
.TP
.B history-preserve-point     
If set to \fBon\fP, the history code attempts to place point at the 
same location on each history line retrived with \fBprevious-history\fP 
or \fBnext-history\fP.
.TP
.B horizontal\-scroll\-mode (Off)
When set to \fBOn\fP, makes readline use a single line for display,
scrolling the input horizontally on a single screen line when it
becomes longer than the screen width rather than wrapping to a new line.
.TP
.B input\-meta (Off)
If set to \fBOn\fP, readline will enable eight-bit input (that is,
it will not clear the eighth bit in the characters it reads),
regardless of what the terminal claims it can support.  The name
.B meta\-flag
is a synonym for this variable.
.TP
.B isearch\-terminators (``C\-[ C\-J'')
The string of characters that should terminate an incremental
search without subsequently executing the character as a command.
If this variable has not been given a value, the characters
\fIESC\fP and \fIC\-J\fP will terminate an incremental search.
.TP
.B keymap (emacs)
Set the current readline keymap.  The set of legal keymap names is
\fIemacs, emacs-standard, emacs-meta, emacs-ctlx, vi, vi-move,
vi-command\fP, and
.IR vi-insert .
\fIvi\fP is equivalent to \fIvi-command\fP; \fIemacs\fP is
equivalent to \fIemacs-standard\fP.  The default value is
.IR emacs .
The value of