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<H1>GNU Readline Library</H1></P><P>
This document describes the GNU Readline Library, a utility which aids
in the consistency of user interface across discrete programs which
provide a command line interface.
</P><P>
<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC1">1. Command Line Editing</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">GNU Readline User's Manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC23">2. Programming with GNU Readline</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">GNU Readline Programmer's Manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC49">A. Copying This Manual</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Copying this manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC52">Concept Index</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Index of concepts described in this manual.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC53">Function and Variable Index</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Index of externally visible functions
and variables.</TD></TR>
</TABLE></BLOCKQUOTE>
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<A NAME="Command Line Editing"></A>
<H1> 1. Command Line Editing </H1>
<!--docid::SEC1::-->
<P>
This chapter describes the basic features of the GNU
command line editing interface.
</P><P>
<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC2">1.1 Introduction to Line Editing</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Notation used in this text.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC3">1.2 Readline Interaction</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">The minimum set of commands for editing a line.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC9">1.3 Readline Init File</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Customizing Readline from a user's view.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC13">1.4 Bindable Readline Commands</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">A description of most of the Readline commands
available for binding</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC22">1.5 Readline vi Mode</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">A short description of how to make Readline
behave like the vi editor.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>
<A NAME="Introduction and Notation"></A>
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<H2> 1.1 Introduction to Line Editing </H2>
<!--docid::SEC2::-->
<P>
The following paragraphs describe the notation used to represent
keystrokes.
</P><P>
The text <KBD>C-k</KBD> is read as `Control-K' and describes the character
produced when the <KBD>k</KBD> key is pressed while the Control key
is depressed.
</P><P>
The text <KBD>M-k</KBD> is read as `Meta-K' and describes the character
produced when the Meta key (if you have one) is depressed, and the <KBD>k</KBD>
key is pressed.
The Meta key is labeled <KBD>ALT</KBD> on many keyboards.
On keyboards with two keys labeled <KBD>ALT</KBD> (usually to either side of
the space bar), the <KBD>ALT</KBD> on the left side is generally set to
work as a Meta key.
The <KBD>ALT</KBD> key on the right may also be configured to work as a
Meta key or may be configured as some other modifier, such as a
Compose key for typing accented characters.
</P><P>
If you do not have a Meta or <KBD>ALT</KBD> key, or another key working as
a Meta key, the identical keystroke can be generated by typing <KBD>ESC</KBD>
<EM>first</EM>, and then typing <KBD>k</KBD>.
Either process is known as <EM>metafying</EM> the <KBD>k</KBD> key.
</P><P>
The text <KBD>M-C-k</KBD> is read as `Meta-Control-k' and describes the
character produced by <EM>metafying</EM> <KBD>C-k</KBD>.
</P><P>
In addition, several keys have their own names. Specifically,
<KBD>DEL</KBD>, <KBD>ESC</KBD>, <KBD>LFD</KBD>, <KBD>SPC</KBD>, <KBD>RET</KBD>, and <KBD>TAB</KBD> all
stand for themselves when seen in this text, or in an init file
(see section <A HREF="readline.html#SEC9">1.3 Readline Init File</A>).
If your keyboard lacks a <KBD>LFD</KBD> key, typing <KBD>C-j</KBD> will
produce the desired character.
The <KBD>RET</KBD> key may be labeled <KBD>Return</KBD> or <KBD>Enter</KBD> on
some keyboards.
</P><P>
<A NAME="Readline Interaction"></A>
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<H2> 1.2 Readline Interaction </H2>
<!--docid::SEC3::-->
<P>
Often during an interactive session you type in a long line of text,
only to notice that the first word on the line is misspelled. The
Readline library gives you a set of commands for manipulating the text
as you type it in, allowing you to just fix your typo, and not forcing
you to retype the majority of the line. Using these editing commands,
you move the cursor to the place that needs correction, and delete or
insert the text of the corrections. Then, when you are satisfied with
the line, you simply press <KBD>RET</KBD>. You do not have to be at the
end of the line to press <KBD>RET</KBD>; the entire line is accepted
regardless of the location of the cursor within the line.
</P><P>
<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC4">1.2.1 Readline Bare Essentials</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">The least you need to know about Readline.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC5">1.2.2 Readline Movement Commands</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Moving about the input line.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC6">1.2.3 Readline Killing Commands</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">How to delete text, and how to get it back!</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC7">1.2.4 Readline Arguments</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Giving numeric arguments to commands.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC8">1.2.5 Searching for Commands in the History</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Searching through previous lines.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>
<A NAME="Readline Bare Essentials"></A>
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<H3> 1.2.1 Readline Bare Essentials </H3>
<!--docid::SEC4::-->
<P>
In order to enter characters into the line, simply type them. The typed
character appears where the cursor was, and then the cursor moves one
space to the right. If you mistype a character, you can use your
erase character to back up and delete the mistyped character.
</P><P>
Sometimes you may mistype a character, and
not notice the error until you have typed several other characters. In
that case, you can type <KBD>C-b</KBD> to move the cursor to the left, and then
correct your mistake. Afterwards, you can move the cursor to the right
with <KBD>C-f</KBD>.
</P><P>
When you add text in the middle of a line, you will notice that characters
to the right of the cursor are `pushed over' to make room for the text
that you have inserted. Likewise, when you delete text behind the cursor,
characters to the right of the cursor are `pulled back' to fill in the
blank space created by the removal of the text. A list of the bare
essentials for editing the text of an input line follows.
</P><P>
<DL COMPACT>
<DT><KBD>C-b</KBD>
<DD>Move back one character.
<DT><KBD>C-f</KBD>
<DD>Move forward one character.
<DT><KBD>DEL</KBD> or <KBD>Backspace</KBD>
<DD>Delete the character to the left of the cursor.
<DT><KBD>C-d</KBD>
<DD>Delete the character underneath the cursor.
<DT>Printing characters
<DD>Insert the character into the line at the cursor.
<DT><KBD>C-_</KBD> or <KBD>C-x C-u</KBD>
<DD>Undo the last editing command. You can undo all the way back to an
empty line.
</DL>
<P>
(Depending on your configuration, the <KBD>Backspace</KBD> key be set to
delete the character to the left of the cursor and the <KBD>DEL</KBD> key set
to delete the character underneath the cursor, like <KBD>C-d</KBD>, rather
than the character to the left of the cursor.)
</P><P>
<A NAME="Readline Movement Commands"></A>
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<H3> 1.2.2 Readline Movement Commands </H3>
<!--docid::SEC5::-->
<P>
The above table describes the most basic keystrokes that you need
in order to do editing of the input line. For your convenience, many
other commands have been added in addition to <KBD>C-b</KBD>, <KBD>C-f</KBD>,
<KBD>C-d</KBD>, and <KBD>DEL</KBD>. Here are some commands for moving more rapidly
about the line.
</P><P>
<DL COMPACT>
<DT><KBD>C-a</KBD>
<DD>Move to the start of the line.
<DT><KBD>C-e</KBD>
<DD>Move to the end of the line.
<DT><KBD>M-f</KBD>
<DD>Move forward a word, where a word is composed of letters and digits.
<DT><KBD>M-b</KBD>
<DD>Move backward a word.
<DT><KBD>C-l</KBD>
<DD>Clear the screen, reprinting the current line at the top.
</DL>
<P>
Notice how <KBD>C-f</KBD> moves forward a character, while <KBD>M-f</KBD> moves
forward a word. It is a loose convention that control keystrokes
operate on characters while meta keystrokes operate on words.
</P><P>
<A NAME="Readline Killing Commands"></A>
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<H3> 1.2.3 Readline Killing Commands </H3>
<!--docid::SEC6::-->
<P>
<A NAME="IDX1"></A>
<A NAME="IDX2"></A>
</P><P>
<EM>Killing</EM> text means to delete the text from the line, but to save
it away for later use, usually by <EM>yanking</EM> (re-inserting)
it back into the line.
(`Cut' and `paste' are more recent jargon for `kill' and `yank'.)
</P><P>
If the description for a command says that it `kills' text, then you can
be sure that you can get the text back in a different (or the same)
place later.
</P><P>
When you use a kill command, the text is saved in a <EM>kill-ring</EM>.
Any number of consecutive kills save all of the killed text together, so
that when you yank it back, you get it all. The kill
ring is not line specific; the text that you killed on a previously
typed line is available to be yanked back later, when you are typing
another line.
<A NAME="IDX3"></A>
</P><P>
Here is the list of commands for killing text.
</P><P>
<DL COMPACT>
<DT><KBD>C-k</KBD>
<DD>Kill the text from the current cursor position to the end of the line.
<P>
<DT><KBD>M-d</KBD>
<DD>Kill from the cursor to the end of the current word, or, if between
words, to the end of the next word.
Word boundaries are the same as those used by <KBD>M-f</KBD>.
<P>
<DT><KBD>M-<KBD>DEL</KBD></KBD>
<DD>Kill from the cursor the start of the current word, or, if between
words, to the start of the previous word.
Word boundaries are the same as those used by <KBD>M-b</KBD>.
<P>
<DT><KBD>C-w</KBD>
<DD>Kill from the cursor to the previous whitespace. This is different than
<KBD>M-<KBD>DEL</KBD></KBD> because the word boundaries differ.
<P>
</DL>
<P>
Here is how to <EM>yank</EM> the text back into the line. Yanking
means to copy the most-recently-killed text from the kill buffer.
</P><P>
<DL COMPACT>
<DT><KBD>C-y</KBD>
<DD>Yank the most recently killed text back into the buffer at the cursor.
<P>
<DT><KBD>M-y</KBD>
<DD>Rotate the kill-ring, and yank the new top. You can only do this if
the prior command is <KBD>C-y</KBD> or <KBD>M-y</KBD>.
</DL>
<P>
<A NAME="Readline Arguments"></A>
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<H3> 1.2.4 Readline Arguments </H3>
<!--docid::SEC7::-->
<P>
You can pass numeric arguments to Readline commands. Sometimes the
argument acts as a repeat count, other times it is the <I>sign</I> of the
argument that is significant. If you pass a negative argument to a
command which normally acts in a forward direction, that command will
act in a backward direction. For example, to kill text back to the
start of the line, you might type <SAMP>`M-- C-k'</SAMP>.
</P><P>
The general way to pass numeric arguments to a command is to type meta
digits before the command. If the first `digit' typed is a minus
sign (<SAMP>`-'</SAMP>), then the sign of the argument will be negative. Once
you have typed one meta digit to get the argument started, you can type
the remainder of the digits, and then the command. For example, to give
the <KBD>C-d</KBD> command an argument of 10, you could type <SAMP>`M-1 0 C-d'</SAMP>,
which will delete the next ten characters on the input line.
</P><P>
<A NAME="Searching"></A>
<HR SIZE="6">
<A NAME="SEC8"></A>
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<H3> 1.2.5 Searching for Commands in the History </H3>
<!--docid::SEC8::-->
<P>
Readline provides commands for searching through the command history
for lines containing a specified string.
There are two search modes: <EM>incremental</EM> and <EM>non-incremental</EM>.
</P><P>
Incremental searches begin before the user has finished typing the
search string.
As each character of the search string is typed, Readline displays
the next entry from the history matching the string typed so far.
An incremental search requires only as many characters as needed to
find the desired history entry.
To search backward in the history for a particular string, type
<KBD>C-r</KBD>. Typing <KBD>C-s</KBD> searches forward through the history.
The characters present in the value of the <CODE>isearch-terminators</CODE> variable
are used to terminate an incremental search.
If that variable has not been assigned a value, the <KBD>ESC</KBD> and
<KBD>C-J</KBD> characters will terminate an incremental search.
<KBD>C-g</KBD> will abort an incremental search and restore the original line.
When the search is terminated, the history entry containing the
search string becomes the current line.
</P><P>
To find other matching entries in the history list, type <KBD>C-r</KBD> or
<KBD>C-s</KBD> as appropriate.
This will search backward or forward in the history for the next
entry matching the search string typed so far.
Any other key sequence bound to a Readline command will terminate
the search and execute that command.
For instance, a <KBD>RET</KBD> will terminate the search and accept
the line, thereby executing the command from the history list.
A movement command will terminate the search, make the last line found
the current line, and begin editing.
</P><P>
Readline remembers the last incremental search string. If two
<KBD>C-r</KBD>s are typed without any intervening characters defining a new
search string, any remembered search string is used.
</P><P>
Non-incremental searches read the entire search string before starting
to search for matching history lines. The search string may be
typed by the user or be part of the contents of the current line.
</P><P>
<A NAME="Readline Init File"></A>
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<H2> 1.3 Readline Init File </H2>
<!--docid::SEC9::-->
<P>
Although the Readline library comes with a set of Emacs-like
keybindings installed by default, it is possible to use a different set
of keybindings.
Any user can customize programs that use Readline by putting
commands in an <EM>inputrc</EM> file, conventionally in his home directory.
The name of this
file is taken from the value of the environment variable <CODE>INPUTRC</CODE>. If
that variable is unset, the default is <TT>`~/.inputrc'</TT>.
</P><P>
When a program which uses the Readline library starts up, the
init file is read, and the key bindings are set.
</P><P>
In addition, the <CODE>C-x C-r</CODE> command re-reads this init file, thus
incorporating any changes that you might have made to it.
</P><P>
<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC10">1.3.1 Readline Init File Syntax</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Syntax for the commands in the inputrc file.</TD></TR>
</TABLE>
<br>
<TABLE BORDER=0 CELLSPACING=0>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC11">1.3.2 Conditional Init Constructs</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Conditional key bindings in the inputrc file.</TD></TR>
</TABLE>
<br>
<TABLE BORDER=0 CELLSPACING=0>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC12">1.3.3 Sample Init File</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">An example inputrc file.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>
<A NAME="Readline Init File Syntax"></A>
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</TR></TABLE>
<H3> 1.3.1 Readline Init File Syntax </H3>
<!--docid::SEC10::-->
<P>
There are only a few basic constructs allowed in the
Readline init file. Blank lines are ignored.
Lines beginning with a <SAMP>`#'</SAMP> are comments.
Lines beginning with a <SAMP>`$'</SAMP> indicate conditional
constructs (see section <A HREF="readline.html#SEC11">1.3.2 Conditional Init Constructs</A>). Other lines
denote variable settings and key bindings.
</P><P>
<DL COMPACT>
<DT>Variable Settings
<DD>You can modify the run-time behavior of Readline by
altering the values of variables in Readline
using the <CODE>set</CODE> command within the init file.
The syntax is simple:
<P>
<TABLE><tr><td>&nbsp;</td><td class=example><pre>set <VAR>variable</VAR> <VAR>value</VAR>
</pre></td></tr></table></P><P>
Here, for example, is how to
change from the default Emacs-like key binding to use
<CODE>vi</CODE> line editing commands:
</P><P>
<TABLE><tr><td>&nbsp;</td><td class=example><pre>set editing-mode vi
</pre></td></tr></table></P><P>
Variable names and values, where appropriate, are recognized without regard
to case. Unrecognized variable names are ignored.
</P><P>
Boolean variables (those that can be set to on or off) are set to on if
the value is null or empty, <VAR>on</VAR> (case-insensitive), or 1. Any other
value results in the variable being set to off.
</P><P>
A great deal of run-time behavior is changeable with the following
variables.
</P><P>
<A NAME="IDX4"></A>
<DL COMPACT>
<DT><CODE>bell-style</CODE>
<DD><A NAME="IDX5"></A>
Controls what happens when Readline wants to ring the terminal bell.
If set to <SAMP>`none'</SAMP>, Readline never rings the bell. If set to
<SAMP>`visible'</SAMP>, Readline uses a visible bell if one is available.
If set to <SAMP>`audible'</SAMP> (the default), Readline attempts to ring
the terminal's bell.
<P>
<DT><CODE>bind-tty-special-chars</CODE>
<DD><A NAME="IDX6"></A>
If set to <SAMP>`on'</SAMP>, Readline attempts to bind the control characters
treated specially by the kernel's terminal driver to their Readline
equivalents.
<P>
<DT><CODE>comment-begin</CODE>
<DD><A NAME="IDX7"></A>
The string to insert at the beginning of the line when the
<CODE>insert-comment</CODE> command is executed. The default value
is <CODE>"#"</CODE>.
<P>
<DT><CODE>completion-ignore-case</CODE>
<DD>If set to <SAMP>`on'</SAMP>, Readline performs filename matching and completion
in a case-insensitive fashion.
The default value is <SAMP>`off'</SAMP>.
<P>
<DT><CODE>completion-query-items</CODE>
<DD><A NAME="IDX8"></A>
The number of possible completions that determines when the user is
asked whether the list of possibilities should be displayed.
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.
A negative value means Readline should never ask.
The default limit is <CODE>100</CODE>.
<P>
<DT><CODE>convert-meta</CODE>
<DD><A NAME="IDX9"></A>
If set to <SAMP>`on'</SAMP>, Readline will convert characters with the
eighth bit set to an ASCII key sequence by stripping the eighth
bit and prefixing an <KBD>ESC</KBD> character, converting them to a
meta-prefixed key sequence. The default value is <SAMP>`on'</SAMP>.
<P>
<DT><CODE>disable-completion</CODE>
<DD><A NAME="IDX10"></A>
If set to <SAMP>`On'</SAMP>, Readline will inhibit word completion.
Completion characters will be inserted into the line as if they had
been mapped to <CODE>self-insert</CODE>. The default is <SAMP>`off'</SAMP>.
<P>
<DT><CODE>editing-mode</CODE>
<DD><A NAME="IDX11"></A>
The <CODE>editing-mode</CODE> 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'</SAMP> or <SAMP>`vi'</SAMP>.
<P>
<DT><CODE>enable-keypad</CODE>
<DD><A NAME="IDX12"></A>
When set to <SAMP>`on'</SAMP>, 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'</SAMP>.
<P>
<DT><CODE>expand-tilde</CODE>
<DD><A NAME="IDX13"></A>
If set to <SAMP>`on'</SAMP>, tilde expansion is performed when Readline
attempts word completion. The default is <SAMP>`off'</SAMP>.
<P>
<DT><CODE>history-preserve-point</CODE>
<DD><A NAME="IDX14"></A>
If set to <SAMP>`on'</SAMP>, the history code attempts to place point at the
same location on each history line retrieved with <CODE>previous-history</CODE>
or <CODE>next-history</CODE>. The default is <SAMP>`off'</SAMP>.
<P>
<DT><CODE>horizontal-scroll-mode</CODE>
<DD><A NAME="IDX15"></A>
This variable can be set to either <SAMP>`on'</SAMP> or <SAMP>`off'</SAMP>. Setting it
to <SAMP>`on'</SAMP> 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'</SAMP>.
<P>
<DT><CODE>input-meta</CODE>
<DD><A NAME="IDX16"></A>
<A NAME="IDX17"></A>
If set to <SAMP>`on'</SAMP>, 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'</SAMP>. The name <CODE>meta-flag</CODE> is a
synonym for this variable.
<P>
<DT><CODE>isearch-terminators</CODE>
<DD><A NAME="IDX18"></A>
The string of characters that should terminate an incremental search without
subsequently executing the character as a command (see section <A HREF="readline.html#SEC8">1.2.5 Searching for Commands in the History</A>).
If this variable has not been given a value, the characters <KBD>ESC</KBD> and
<KBD>C-J</KBD> will terminate an incremental search.
<P>
<DT><CODE>keymap</CODE>
<DD><A NAME="IDX19"></A>
Sets Readline's idea of the current keymap for key binding commands.
Acceptable <CODE>keymap</CODE> names are
<CODE>emacs</CODE>,
<CODE>emacs-standard</CODE>,
<CODE>emacs-meta</CODE>,
<CODE>emacs-ctlx</CODE>,
<CODE>vi</CODE>,
<CODE>vi-move</CODE>,
<CODE>vi-command</CODE>, and
<CODE>vi-insert</CODE>.
<CODE>vi</CODE> is equivalent to <CODE>vi-command</CODE>; <CODE>emacs</CODE> is
equivalent to <CODE>emacs-standard</CODE>. The default value is <CODE>emacs</CODE>.
The value of the <CODE>editing-mode</CODE> variable also affects the
default keymap.
<P>
<DT><CODE>mark-directories</CODE>
<DD>If set to <SAMP>`on'</SAMP>, completed directory names have a slash
appended. The default is <SAMP>`on'</SAMP>.
<P>
<DT><CODE>mark-modified-lines</CODE>
<DD><A NAME="IDX20"></A>
This variable, when set to <SAMP>`on'</SAMP>, causes Readline to display an
asterisk (<SAMP>`*'</SAMP>) at the start of history lines which have been modified.
This variable is <SAMP>`off'</SAMP> by default.
<P>
<DT><CODE>mark-symlinked-directories</CODE>
<DD><A NAME="IDX21"></A>
If set to <SAMP>`on'</SAMP>, completed names which are symbolic links
to directories have a slash appended (subject to the value of
<CODE>mark-directories</CODE>).
The default is <SAMP>`off'</SAMP>.
<P>
<DT><CODE>match-hidden-files</CODE>
<DD><A NAME="IDX22"></A>
This variable, when set to <SAMP>`on'</SAMP>, causes Readline to match files whose
names begin with a <SAMP>`.'</SAMP> (hidden files) when performing filename
completion, unless the leading <SAMP>`.'</SAMP> is
supplied by the user in the filename to be completed.
This variable is <SAMP>`on'</SAMP> by default.
<P>
<DT><CODE>output-meta</CODE>
<DD><A NAME="IDX23"></A>
If set to <SAMP>`on'</SAMP>, Readline will display characters with the
eighth bit set directly rather than as a meta-prefixed escape
sequence. The default is <SAMP>`off'</SAMP>.
<P>
<DT><CODE>page-completions</CODE>
<DD><A NAME="IDX24"></A>
If set to <SAMP>`on'</SAMP>, Readline uses an internal <CODE>more</CODE>-like pager
to display a screenful of possible completions at a time.
This variable is <SAMP>`on'</SAMP> by default.
<P>
<DT><CODE>print-completions-horizontally</CODE>
<DD>If set to <SAMP>`on'</SAMP>, Readline will display completions with matches
sorted horizontally in alphabetical order, rather than down the screen.
The default is <SAMP>`off'</SAMP>.
<P>
<DT><CODE>show-all-if-ambiguous</CODE>
<DD><A NAME="IDX25"></A>
This alters the default behavior of the completion functions. If
set to <SAMP>`on'</SAMP>,
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'</SAMP>.
<P>
<DT><CODE>show-all-if-unmodified</CODE>
<DD><A NAME="IDX26"></A>
This alters the default behavior of the completion functions in
a fashion similar to <VAR>show-all-if-ambiguous</VAR>.
If set to <SAMP>`on'</SAMP>,
words which have more than one possible completion without any
possible partial completion (the possible completions don't share
a common prefix) cause the matches to be listed immediately instead
of ringing the bell.
The default value is <SAMP>`off'</SAMP>.
<P>
<DT><CODE>visible-stats</CODE>
<DD><A NAME="IDX27"></A>
If set to <SAMP>`on'</SAMP>, a character denoting a file's type
is appended to the filename when listing possible
completions. The default is <SAMP>`off'</SAMP>.
<P>
</DL>
<P>
<DT>Key Bindings
<DD>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.
<P>
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.
</P><P>
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</VAR>).
</P><P>
<DL COMPACT>
<DT><VAR>keyname</VAR>: <VAR>function-name</VAR> or <VAR>macro</VAR>
<DD><VAR>keyname</VAR> is the name of a key spelled out in English. For example:
<TABLE><tr><td>&nbsp;</td><td class=example><pre>Control-u: universal-argument
Meta-Rubout: backward-kill-word
Control-o: "&#62; output"
</pre></td></tr></table><P>
In the above example, <KBD>C-u</KBD> is bound to the function
<CODE>universal-argument</CODE>,
<KBD>M-DEL</KBD> is bound to the function <CODE>backward-kill-word</CODE>, and
<KBD>C-o</KBD> is bound to run the macro
expressed on the right hand side (that is, to insert the text
<SAMP>`&#62; output'</SAMP> into the line).
</P><P>
A number of symbolic character names are recognized while
processing this key binding syntax:
<VAR>DEL</VAR>,
<VAR>ESC</VAR>,
<VAR>ESCAPE</VAR>,
<VAR>LFD</VAR>,
<VAR>NEWLINE</VAR>,
<VAR>RET</VAR>,
<VAR>RETURN</VAR>,
<VAR>RUBOUT</VAR>,
<VAR>SPACE</VAR>,
<VAR>SPC</VAR>,
and
<VAR>TAB</VAR>.
</P><P>
<DT>"<VAR>keyseq</VAR>": <VAR>function-name</VAR> or <VAR>macro</VAR>
<DD><VAR>keyseq</VAR> differs from <VAR>keyname</VAR> above in that strings
denoting an entire key sequence can be specified, by placing
the key sequence in double quotes. Some GNU Emacs style key
escapes can be used, as in the following example, but the
special character names are not recognized.
<P>
<TABLE><tr><td>&nbsp;</td><td class=example><pre>"\C-u": universal-argument
"\C-x\C-r": re-read-init-file
"\e[11~": "Function Key 1"
</pre></td></tr></table></P><P>
In the above example, <KBD>C-u</KBD> is again bound to the function
<CODE>universal-argument</CODE> (just as it was in the first example),
<SAMP>`<KBD>C-x</KBD> <KBD>C-r</KBD>'</SAMP> is bound to the function <CODE>re-read-init-file</CODE>,
and <SAMP>`<KBD>ESC</KBD> <KBD>[</KBD> <KBD>1</KBD> <KBD>1</KBD> <KBD>~</KBD>'</SAMP> is bound to insert
the text <SAMP>`Function Key 1'</SAMP>.
</P><P>
</DL>
<P>
The following GNU Emacs style escape sequences are available when
specifying key sequences:
</P><P>
<DL COMPACT>
<DT><CODE><KBD>\C-</KBD></CODE>
<DD>control prefix
<DT><CODE><KBD>\M-</KBD></CODE>
<DD>meta prefix
<DT><CODE><KBD>\e</KBD></CODE>
<DD>an escape character
<DT><CODE><KBD>\\</KBD></CODE>
<DD>backslash
<DT><CODE><KBD>\"</KBD></CODE>
<DD><KBD>"</KBD>, a double quotation mark
<DT><CODE><KBD>\'</KBD></CODE>
<DD><KBD>'</KBD>, a single quote or apostrophe
</DL>
<P>
In addition to the GNU Emacs style escape sequences, a second
set of backslash escapes is available:
</P><P>
<DL COMPACT>
<DT><CODE>\a</CODE>
<DD>alert (bell)
<DT><CODE>\b</CODE>
<DD>backspace
<DT><CODE>\d</CODE>
<DD>delete
<DT><CODE>\f</CODE>
<DD>form feed
<DT><CODE>\n</CODE>
<DD>newline
<DT><CODE>\r</CODE>
<DD>carriage return
<DT><CODE>\t</CODE>
<DD>horizontal tab
<DT><CODE>\v</CODE>
<DD>vertical tab
<DT><CODE>\<VAR>nnn</VAR></CODE>
<DD>the eight-bit character whose value is the octal value <VAR>nnn</VAR>
(one to three digits)
<DT><CODE>\x<VAR>HH</VAR></CODE>
<DD>the eight-bit character whose value is the hexadecimal value <VAR>HH</VAR>
(one or two hex digits)
</DL>
<P>
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>`"'</SAMP> and <SAMP>`''</SAMP>.
For example, the following binding will make <SAMP>`<KBD>C-x</KBD> \'</SAMP>
insert a single <SAMP>`\'</SAMP> into the line:
<TABLE><tr><td>&nbsp;</td><td class=example><pre>"\C-x\\": "\\"
</pre></td></tr></table></P><P>
</DL>
<P>
<A NAME="Conditional Init Constructs"></A>
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</TR></TABLE>
<H3> 1.3.2 Conditional Init Constructs </H3>
<!--docid::SEC11::-->
<P>
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.
</P><P>
<DL COMPACT>
<DT><CODE>$if</CODE>
<DD>The <CODE>$if</CODE> construct allows bindings to be made based on the
editing mode, the terminal being used, or the application using
Readline. The text of the test extends to the end of the line;
no characters are required to isolate it.
<P>
<DL COMPACT>
<DT><CODE>mode</CODE>
<DD>The <CODE>mode=</CODE> form of the <CODE>$if</CODE> directive is used to test
whether Readline is in <CODE>emacs</CODE> or <CODE>vi</CODE> mode.
This may be used in conjunction
with the <SAMP>`set keymap'</SAMP> command, for instance, to set bindings in
the <CODE>emacs-standard</CODE> and <CODE>emacs-ctlx</CODE> keymaps only if
Readline is starting out in <CODE>emacs</CODE> mode.
<P>
<DT><CODE>term</CODE>
<DD>The <CODE>term=</CODE> form may be used to include terminal-specific
key bindings, perhaps to bind the key sequences output by the
terminal's function keys. The word on the right side of the
<SAMP>`='</SAMP> is tested against both the full name of the terminal and
the portion of the terminal name before the first <SAMP>`-'</SAMP>. This
allows <CODE>sun</CODE> to match both <CODE>sun</CODE> and <CODE>sun-cmd</CODE>,
for instance.
<P>
<DT><CODE>application</CODE>
<DD>The <VAR>application</VAR> construct is used to include
application-specific settings. Each program using the Readline
library sets the <VAR>application name</VAR>, and you can test for
a particular value.
This could be used to bind key sequences to functions useful for
a specific program. For instance, the following command adds a
key sequence that quotes the current or previous word in Bash:
<TABLE><tr><td>&nbsp;</td><td class=example><pre>$if Bash
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
$endif
</pre></td></tr></table></DL>
<P>
<DT><CODE>$endif</CODE>
<DD>This command, as seen in the previous example, terminates an
<CODE>$if</CODE> command.
<P>
<DT><CODE>$else</CODE>
<DD>Commands in this branch of the <CODE>$if</CODE> directive are executed if
the test fails.
<P>
<DT><CODE>$include</CODE>
<DD>This directive takes a single filename as an argument and reads commands
and bindings from that file.
For example, the following directive reads from <TT>`/etc/inputrc'</TT>:
<TABLE><tr><td>&nbsp;</td><td class=example><pre>$include /etc/inputrc
</pre></td></tr></table></DL>
<P>
<A NAME="Sample Init File"></A>
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<H3> 1.3.3 Sample Init File </H3>
<!--docid::SEC12::-->
<P>
Here is an example of an <VAR>inputrc</VAR> file. This illustrates key
binding, variable assignment, and conditional syntax.
</P><P>
<TABLE><tr><td>&nbsp;</td><td class=example><pre># This file controls the behaviour of line input editing for
# programs that use the GNU Readline library. Existing
# programs include FTP, Bash, and GDB.
#
# You can re-read the inputrc file with C-x C-r.
# Lines beginning with '#' are comments.
#
# First, include any systemwide bindings and variable
# assignments from /etc/Inputrc
$include /etc/Inputrc
#
# Set various bindings for emacs mode.
set editing-mode emacs
$if mode=emacs
Meta-Control-h: backward-kill-word Text after the function name is ignored
#
# Arrow keys in keypad mode
#
#"\M-OD": backward-char
#"\M-OC": forward-char
#"\M-OA": previous-history
#"\M-OB": next-history
#
# Arrow keys in ANSI mode
#
"\M-[D": backward-char
"\M-[C": forward-char
"\M-[A": previous-history
"\M-[B": next-history
#
# Arrow keys in 8 bit keypad mode
#
#"\M-\C-OD": backward-char
#"\M-\C-OC": forward-char
#"\M-\C-OA": previous-history
#"\M-\C-OB": next-history
#
# Arrow keys in 8 bit ANSI mode
#
#"\M-\C-[D": backward-char
#"\M-\C-[C": forward-char
#"\M-\C-[A": previous-history
#"\M-\C-[B": next-history
C-q: quoted-insert
$endif
# An old-style binding. This happens to be the default.
TAB: complete
# Macros that are convenient for shell interaction
$if Bash
# edit the path
"\C-xp": "PATH=${PATH}\e\C-e\C-a\ef\C-f"
# prepare to type a quoted word --
# insert open and close double quotes
# and move to just after the open quote
"\C-x\"": "\"\"\C-b"
# insert a backslash (testing backslash escapes
# in sequences and macros)
"\C-x\\": "\\"
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
# Add a binding to refresh the line, which is unbound
"\C-xr": redraw-current-line
# Edit variable on current line.
"\M-\C-v": "\C-a\C-k$\C-y\M-\C-e\C-a\C-y="
$endif
# use a visible bell if one is available
set bell-style visible
# don't strip characters to 7 bits when reading
set input-meta on
# allow iso-latin1 characters to be inserted rather
# than converted to prefix-meta sequences
set convert-meta off
# display characters with the eighth bit set directly
# rather than as meta-prefixed characters
set output-meta on
# if there are more than 150 possible completions for
# a word, ask the user if he wants to see all of them
set completion-query-items 150
# For FTP
$if Ftp
"\C-xg": "get \M-?"
"\C-xt": "put \M-?"
"\M-.": yank-last-arg
$endif
</pre></td></tr></table></P><P>
<A NAME="Bindable Readline Commands"></A>
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<H2> 1.4 Bindable Readline Commands </H2>
<!--docid::SEC13::-->
<P>
<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC14">1.4.1 Commands For Moving</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Moving about the line.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC15">1.4.2 Commands For Manipulating The History</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Getting at previous lines.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC16">1.4.3 Commands For Changing Text</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Commands for changing text.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC17">1.4.4 Killing And Yanking</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Commands for killing and yanking.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC18">1.4.5 Specifying Numeric Arguments</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Specifying numeric arguments, repeat counts.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC19">1.4.6 Letting Readline Type For You</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Getting Readline to do the typing for you.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC20">1.4.7 Keyboard Macros</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Saving and re-executing typed characters</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC21">1.4.8 Some Miscellaneous Commands</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Other miscellaneous commands.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>
This section describes Readline commands that may be bound to key
sequences.
Command names without an accompanying key sequence are unbound by default.
</P><P>
In the following descriptions, <EM>point</EM> refers to the current cursor
position, and <EM>mark</EM> refers to a cursor position saved by the
<CODE>set-mark</CODE> command.
The text between the point and mark is referred to as the <EM>region</EM>.
</P><P>
<A NAME="Commands For Moving"></A>
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<H3> 1.4.1 Commands For Moving </H3>
<!--docid::SEC14::-->
<DL COMPACT>
<A NAME="IDX28"></A>
<DT><CODE>beginning-of-line (C-a)</CODE>
<DD><A NAME="IDX29"></A>
Move to the start of the current line.
<P>
<A NAME="IDX30"></A>
<DT><CODE>end-of-line (C-e)</CODE>
<DD><A NAME="IDX31"></A>
Move to the end of the line.
<P>
<A NAME="IDX32"></A>
<DT><CODE>forward-char (C-f)</CODE>
<DD><A NAME="IDX33"></A>
Move forward a character.
<P>
<A NAME="IDX34"></A>
<DT><CODE>backward-char (C-b)</CODE>
<DD><A NAME="IDX35"></A>
Move back a character.
<P>
<A NAME="IDX36"></A>
<DT><CODE>forward-word (M-f)</CODE>
<DD><A NAME="IDX37"></A>
Move forward to the end of the next word. Words are composed of
letters and digits.
<P>
<A NAME="IDX38"></A>
<DT><CODE>backward-word (M-b)</CODE>
<DD><A NAME="IDX39"></A>
Move back to the start of the current or previous word. Words are
composed of letters and digits.
<P>
<A NAME="IDX40"></A>
<DT><CODE>clear-screen (C-l)</CODE>
<DD><A NAME="IDX41"></A>
Clear the screen and redraw the current line,
leaving the current line at the top of the screen.
<P>
<A NAME="IDX42"></A>
<DT><CODE>redraw-current-line ()</CODE>
<DD><A NAME="IDX43"></A>
Refresh the current line. By default, this is unbound.
<P>
</DL>
<P>
<A NAME="Commands For History"></A>
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<H3> 1.4.2 Commands For Manipulating The History </H3>
<!--docid::SEC15::-->
<P>
<DL COMPACT>
<A NAME="IDX44"></A>
<DT><CODE>accept-line (Newline or Return)</CODE>
<DD><A NAME="IDX45"></A>
Accept the line regardless of where the cursor is.
If this line is
non-empty, it may be added to the history list for future recall with
<CODE>add_history()</CODE>.
If this line is a modified history line, the history line is restored
to its original state.
<P>
<A NAME="IDX46"></A>
<DT><CODE>previous-history (C-p)</CODE>
<DD><A NAME="IDX47"></A>
Move `back' through the history list, fetching the previous command.
<P>
<A NAME="IDX48"></A>
<DT><CODE>next-history (C-n)</CODE>
<DD><A NAME="IDX49"></A>
Move `forward' through the history list, fetching the next command.
<P>
<A NAME="IDX50"></A>
<DT><CODE>beginning-of-history (M-&#60;)</CODE>
<DD><A NAME="IDX51"></A>
Move to the first line in the history.
<P>
<A NAME="IDX52"></A>
<DT><CODE>end-of-history (M-&#62;)</CODE>
<DD><A NAME="IDX53"></A>
Move to the end of the input history, i.e., the line currently
being entered.
<P>
<A NAME="IDX54"></A>
<DT><CODE>reverse-search-history (C-r)</CODE>
<DD><A NAME="IDX55"></A>
Search backward starting at the current line and moving `up' through
the history as necessary. This is an incremental search.
<P>
<A NAME="IDX56"></A>
<DT><CODE>forward-search-history (C-s)</CODE>
<DD><A NAME="IDX57"></A>
Search forward starting at the current line and moving `down' through
the the history as necessary. This is an incremental search.
<P>
<A NAME="IDX58"></A>
<DT><CODE>non-incremental-reverse-search-history (M-p)</CODE>
<DD><A NAME="IDX59"></A>
Search backward starting at the current line and moving `up'
through the history as necessary using a non-incremental search
for a string supplied by the user.
<P>
<A NAME="IDX60"></A>
<DT><CODE>non-incremental-forward-search-history (M-n)</CODE>
<DD><A NAME="IDX61"></A>
Search forward starting at the current line and moving `down'
through the the history as necessary using a non-incremental search
for a string supplied by the user.
<P>
<A NAME="IDX62"></A>
<DT><CODE>history-search-forward ()</CODE>
<DD><A NAME="IDX63"></A>
Search forward through the history for the string of characters
between the start of the current line and the point.
This is a non-incremental search.
By default, this command is unbound.
<P>
<A NAME="IDX64"></A>
<DT><CODE>history-search-backward ()</CODE>
<DD><A NAME="IDX65"></A>
Search backward through the history for the string of characters
between the start of the current line and the point. This
is a non-incremental search. By default, this command is unbound.
<P>
<A NAME="IDX66"></A>
<DT><CODE>yank-nth-arg (M-C-y)</CODE>
<DD><A NAME="IDX67"></A>
Insert the first argument to the previous command (usually
the second word on the previous line) at point.
With an argument <VAR>n</VAR>,
insert the <VAR>n</VAR>th word from the previous command (the words
in the previous command begin with word 0). A negative argument
inserts the <VAR>n</VAR>th word from the end of the previous command.
Once the argument <VAR>n</VAR> is computed, the argument is extracted
as if the <SAMP>`!<VAR>n</VAR>'</SAMP> history expansion had been specified.
<P>
<A NAME="IDX68"></A>
<DT><CODE>yank-last-arg (M-. or M-_)</CODE>
<DD><A NAME="IDX69"></A>
Insert last argument to the previous command (the last word of the
previous history entry). With an
argument, behave exactly like <CODE>yank-nth-arg</CODE>.
Successive calls to <CODE>yank-last-arg</CODE> move back through the history
list, inserting the last argument of each line in turn.
The history expansion facilities are used to extract the last argument,
as if the <SAMP>`!$'</SAMP> history expansion had been specified.
<P>
</DL>
<P>
<A NAME="Commands For Text"></A>
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<H3> 1.4.3 Commands For Changing Text </H3>
<!--docid::SEC16::-->
<P>
<DL COMPACT>
<A NAME="IDX70"></A>
<DT><CODE>delete-char (C-d)</CODE>
<DD><A NAME="IDX71"></A>
Delete the character at point. If point is at the
beginning of the line, there are no characters in the line, and
the last character typed was not bound to <CODE>delete-char</CODE>, then
return EOF.
<P>
<A NAME="IDX72"></A>
<DT><CODE>backward-delete-char (Rubout)</CODE>
<DD><A NAME="IDX73"></A>
Delete the character behind the cursor. A numeric argument means
to kill the characters instead of deleting them.
<P>
<A NAME="IDX74"></A>
<DT><CODE>forward-backward-delete-char ()</CODE>
<DD><A NAME="IDX75"></A>
Delete the character under the cursor, unless the cursor is at the
end of the line, in which case the character behind the cursor is
deleted. By default, this is not bound to a key.
<P>
<A NAME="IDX76"></A>
<DT><CODE>quoted-insert (C-q or C-v)</CODE>
<DD><A NAME="IDX77"></A>
Add the next character typed to the line verbatim. This is
how to insert key sequences like <KBD>C-q</KBD>, for example.
<P>
<A NAME="IDX78"></A>
<DT><CODE>tab-insert (M-<KBD>TAB</KBD>)</CODE>
<DD><A NAME="IDX79"></A>
Insert a tab character.
<P>
<A NAME="IDX80"></A>
<DT><CODE>self-insert (a, b, A, 1, !, <small>...</small>)</CODE>
<DD><A NAME="IDX81"></A>
Insert yourself.
<P>
<A NAME="IDX82"></A>
<DT><CODE>transpose-chars (C-t)</CODE>
<DD><A NAME="IDX83"></A>
Drag the character before the cursor forward over
the character at the cursor, moving the
cursor forward as well. If the insertion point
is at the end of the line, then this
transposes the last two characters of the line.
Negative arguments have no effect.
<P>
<A NAME="IDX84"></A>
<DT><CODE>transpose-words (M-t)</CODE>
<DD><A NAME="IDX85"></A>
Drag the word before point past the word after point,
moving point past that word as well.
If the insertion point is at the end of the line, this transposes
the last two words on the line.
<P>
<A NAME="IDX86"></A>
<DT><CODE>upcase-word (M-u)</CODE>
<DD><A NAME="IDX87"></A>
Uppercase the current (or following) word. With a negative argument,
uppercase the previous word, but do not move the cursor.
<P>
<A NAME="IDX88"></A>
<DT><CODE>downcase-word (M-l)</CODE>
<DD><A NAME="IDX89"></A>
Lowercase the current (or following) word. With a negative argument,
lowercase the previous word, but do not move the cursor.
<P>
<A NAME="IDX90"></A>
<DT><CODE>capitalize-word (M-c)</CODE>
<DD><A NAME="IDX91"></A>
Capitalize the current (or following) word. With a negative argument,
capitalize the previous word, but do not move the cursor.
<P>
<A NAME="IDX92"></A>
<DT><CODE>overwrite-mode ()</CODE>
<DD><A NAME="IDX93"></A>
Toggle overwrite mode. With an explicit positive numeric argument,
switches to overwrite mode. With an explicit non-positive numeric
argument, switches to insert mode. This command affects only
<CODE>emacs</CODE> mode; <CODE>vi</CODE> mode does overwrite differently.
Each call to <CODE>readline()</CODE> starts in insert mode.
<P>
In overwrite mode, characters bound to <CODE>self-insert</CODE> replace
the text at point rather than pushing the text to the right.
Characters bound to <CODE>backward-delete-char</CODE> replace the character
before point with a space.
</P><P>
By default, this command is unbound.
</P><P>
</DL>
<P>
<A NAME="Commands For Killing"></A>
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<H3> 1.4.4 Killing And Yanking </H3>
<!--docid::SEC17::-->
<P>
<DL COMPACT>
<A NAME="IDX94"></A>
<DT><CODE>kill-line (C-k)</CODE>
<DD><A NAME="IDX95"></A>
Kill the text from point to the end of the line.
<P>
<A NAME="IDX96"></A>
<DT><CODE>backward-kill-line (C-x Rubout)</CODE>
<DD><A NAME="IDX97"></A>
Kill backward to the beginning of the line.
<P>
<A NAME="IDX98"></A>
<DT><CODE>unix-line-discard (C-u)</CODE>
<DD><A NAME="IDX99"></A>
Kill backward from the cursor to the beginning of the current line.
<P>
<A NAME="IDX100"></A>
<DT><CODE>kill-whole-line ()</CODE>
<DD><A NAME="IDX101"></A>
Kill all characters on the current line, no matter where point is.
By default, this is unbound.
<P>
<A NAME="IDX102"></A>
<DT><CODE>kill-word (M-d)</CODE>
<DD><A NAME="IDX103"></A>
Kill from point to the end of the current word, or if between
words, to the end of the next word.
Word boundaries are the same as <CODE>forward-word</CODE>.
<P>
<A NAME="IDX104"></A>
<DT><CODE>backward-kill-word (M-<KBD>DEL</KBD>)</CODE>
<DD><A NAME="IDX105"></A>
Kill the word behind point.
Word boundaries are the same as <CODE>backward-word</CODE>.
<P>
<A NAME="IDX106"></A>
<DT><CODE>unix-word-rubout (C-w)</CODE>
<DD><A NAME="IDX107"></A>
Kill the word behind point, using white space as a word boundary.
The killed text is saved on the kill-ring.
<P>
<A NAME="IDX108"></A>
<DT><CODE>unix-filename-rubout ()</CODE>
<DD><A NAME="IDX109"></A>
Kill the word behind point, using white space and the slash character
as the word boundaries.
The killed text is saved on the kill-ring.
<P>
<A NAME="IDX110"></A>
<DT><CODE>delete-horizontal-space ()</CODE>
<DD><A NAME="IDX111"></A>
Delete all spaces and tabs around point. By default, this is unbound.
<P>
<A NAME="IDX112"></A>
<DT><CODE>kill-region ()</CODE>
<DD><A NAME="IDX113"></A>
Kill the text in the current region.
By default, this command is unbound.
<P>
<A NAME="IDX114"></A>
<DT><CODE>copy-region-as-kill ()</CODE>
<DD><A NAME="IDX115"></A>
Copy the text in the region to the kill buffer, so it can be yanked
right away. By default, this command is unbound.
<P>
<A NAME="IDX116"></A>
<DT><CODE>copy-backward-word ()</CODE>
<DD><A NAME="IDX117"></A>
Copy the word before point to the kill buffer.
The word boundaries are the same as <CODE>backward-word</CODE>.
By default, this command is unbound.
<P>
<A NAME="IDX118"></A>
<DT><CODE>copy-forward-word ()</CODE>
<DD><A NAME="IDX119"></A>
Copy the word following point to the kill buffer.
The word boundaries are the same as <CODE>forward-word</CODE>.
By default, this command is unbound.
<P>
<A NAME="IDX120"></A>
<DT><CODE>yank (C-y)</CODE>
<DD><A NAME="IDX121"></A>
Yank the top of the kill ring into the buffer at point.
<P>
<A NAME="IDX122"></A>
<DT><CODE>yank-pop (M-y)</CODE>
<DD><A NAME="IDX123"></A>
Rotate the kill-ring, and yank the new top. You can only do this if
the prior command is <CODE>yank</CODE> or <CODE>yank-pop</CODE>.
</DL>
<P>
<A NAME="Numeric Arguments"></A>
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<H3> 1.4.5 Specifying Numeric Arguments </H3>
<!--docid::SEC18::-->
<DL COMPACT>
<A NAME="IDX124"></A>
<DT><CODE>digit-argument (<KBD>M-0</KBD>, <KBD>M-1</KBD>, <small>...</small> <KBD>M--</KBD>)</CODE>
<DD><A NAME="IDX125"></A>
Add this digit to the argument already accumulating, or start a new
argument. <KBD>M--</KBD> starts a negative argument.
<P>
<A NAME="IDX126"></A>
<DT><CODE>universal-argument ()</CODE>
<DD><A NAME="IDX127"></A>
This is another way to specify an argument.
If this command is followed by one or more digits, optionally with a
leading minus sign, those digits define the argument.
If the command is followed by digits, executing <CODE>universal-argument</CODE>
again ends the numeric argument, but is otherwise ignored.
As a special case, if this command is immediately followed by a
character that is neither a digit or minus sign, the argument count
for the next command is multiplied by four.
The argument count is initially one, so executing this function the
first time makes the argument count four, a second time makes the
argument count sixteen, and so on.
By default, this is not bound to a key.
</DL>
<P>
<A NAME="Commands For Completion"></A>
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<H3> 1.4.6 Letting Readline Type For You </H3>
<!--docid::SEC19::-->
<P>
<DL COMPACT>
<A NAME="IDX128"></A>
<DT><CODE>complete (<KBD>TAB</KBD>)</CODE>
<DD><A NAME="IDX129"></A>
Attempt to perform completion on the text before point.
The actual completion performed is application-specific.
The default is filename completion.
<P>
<A NAME="IDX130"></A>
<DT><CODE>possible-completions (M-?)</CODE>
<DD><A NAME="IDX131"></A>
List the possible completions of the text before point.
<P>
<A NAME="IDX132"></A>
<DT><CODE>insert-completions (M-*)</CODE>
<DD><A NAME="IDX133"></A>
Insert all completions of the text before point that would have
been generated by <CODE>possible-completions</CODE>.
<P>
<A NAME="IDX134"></A>
<DT><CODE>menu-complete ()</CODE>
<DD><A NAME="IDX135"></A>
Similar to <CODE>complete</CODE>, but replaces the word to be completed
with a single match from the list of possible completions.
Repeated execution of <CODE>menu-complete</CODE> steps through the list
of possible completions, inserting each match in turn.
At the end of the list of completions, the bell is rung
(subject to the setting of <CODE>bell-style</CODE>)
and the original text is restored.
An argument of <VAR>n</VAR> moves <VAR>n</VAR> positions forward in the list
of matches; a negative argument may be used to move backward
through the list.
This command is intended to be bound to <KBD>TAB</KBD>, but is unbound
by default.
<P>
<A NAME="IDX136"></A>
<DT><CODE>delete-char-or-list ()</CODE>
<DD><A NAME="IDX137"></A>
Deletes the character under the cursor if not at the beginning or
end of the line (like <CODE>delete-char</CODE>).
If at the end of the line, behaves identically to
<CODE>possible-completions</CODE>.
This command is unbound by default.
<P>
</DL>
<P>
<A NAME="Keyboard Macros"></A>
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<H3> 1.4.7 Keyboard Macros </H3>
<!--docid::SEC20::-->
<DL COMPACT>
<A NAME="IDX138"></A>
<DT><CODE>start-kbd-macro (C-x ()</CODE>
<DD><A NAME="IDX139"></A>
Begin saving the characters typed into the current keyboard macro.
<P>
<A NAME="IDX140"></A>
<DT><CODE>end-kbd-macro (C-x ))</CODE>
<DD><A NAME="IDX141"></A>
Stop saving the characters typed into the current keyboard macro
and save the definition.
<P>
<A NAME="IDX142"></A>
<DT><CODE>call-last-kbd-macro (C-x e)</CODE>
<DD><A NAME="IDX143"></A>
Re-execute the last keyboard macro defined, by making the characters
in the macro appear as if typed at the keyboard.
<P>
</DL>
<P>
<A NAME="Miscellaneous Commands"></A>
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<H3> 1.4.8 Some Miscellaneous Commands </H3>
<!--docid::SEC21::-->
<DL COMPACT>
<A NAME="IDX144"></A>
<DT><CODE>re-read-init-file (C-x C-r)</CODE>
<DD><A NAME="IDX145"></A>
Read in the contents of the <VAR>inputrc</VAR> file, and incorporate
any bindings or variable assignments found there.
<P>
<A NAME="IDX146"></A>
<DT><CODE>abort (C-g)</CODE>
<DD><A NAME="IDX147"></A>
Abort the current editing command and
ring the terminal's bell (subject to the setting of
<CODE>bell-style</CODE>).
<P>
<A NAME="IDX148"></A>
<DT><CODE>do-uppercase-version (M-a, M-b, M-<VAR>x</VAR>, <small>...</small>)</CODE>
<DD><A NAME="IDX149"></A>
If the metafied character <VAR>x</VAR> is lowercase, run the command
that is bound to the corresponding uppercase character.
<P>
<A NAME="IDX150"></A>
<DT><CODE>prefix-meta (<KBD>ESC</KBD>)</CODE>
<DD><A NAME="IDX151"></A>
Metafy the next character typed. This is for keyboards
without a meta key. Typing <SAMP>`<KBD>ESC</KBD> f'</SAMP> is equivalent to typing
<KBD>M-f</KBD>.
<P>
<A NAME="IDX152"></A>
<DT><CODE>undo (C-_ or C-x C-u)</CODE>
<DD><A NAME="IDX153"></A>
Incremental undo, separately remembered for each line.
<P>
<A NAME="IDX154"></A>
<DT><CODE>revert-line (M-r)</CODE>
<DD><A NAME="IDX155"></A>
Undo all changes made to this line. This is like executing the <CODE>undo</CODE>
command enough times to get back to the beginning.
<P>
<A NAME="IDX156"></A>
<DT><CODE>tilde-expand (M-~)</CODE>
<DD><A NAME="IDX157"></A>
Perform tilde expansion on the current word.
<P>
<A NAME="IDX158"></A>
<DT><CODE>set-mark (C-@)</CODE>
<DD><A NAME="IDX159"></A>
Set the mark to the point. If a
numeric argument is supplied, the mark is set to that position.
<P>
<A NAME="IDX160"></A>
<DT><CODE>exchange-point-and-mark (C-x C-x)</CODE>
<DD><A NAME="IDX161"></A>
Swap the point with the mark. The current cursor position is set to
the saved position, and the old cursor position is saved as the mark.
<P>
<A NAME="IDX162"></A>
<DT><CODE>character-search (C-])</CODE>
<DD><A NAME="IDX163"></A>
A character is read and point is moved to the next occurrence of that
character. A negative count searches for previous occurrences.
<P>
<A NAME="IDX164"></A>
<DT><CODE>character-search-backward (M-C-])</CODE>
<DD><A NAME="IDX165"></A>
A character is read and point is moved to the previous occurrence
of that character. A negative count searches for subsequent
occurrences.
<P>
<A NAME="IDX166"></A>
<DT><CODE>insert-comment (M-#)</CODE>
<DD><A NAME="IDX167"></A>
Without a numeric argument, the value of the <CODE>comment-begin</CODE>
variable is inserted at the beginning of the current line.
If a numeric argument is supplied, this command acts as a toggle: if
the characters at the beginning of the line do not match the value
of <CODE>comment-begin</CODE>, the value is inserted, otherwise
the characters in <CODE>comment-begin</CODE> are deleted from the beginning of
the line.
In either case, the line is accepted as if a newline had been typed.
<P>
<A NAME="IDX168"></A>
<DT><CODE>dump-functions ()</CODE>
<DD><A NAME="IDX169"></A>
Print all of the functions and their key bindings to the
Readline output stream. If a numeric argument is supplied,
the output is formatted in such a way that it can be made part
of an <VAR>inputrc</VAR> file. This command is unbound by default.
<P>
<A NAME="IDX170"></A>
<DT><CODE>dump-variables ()</CODE>
<DD><A NAME="IDX171"></A>
Print all of the settable variables and their values to the
Readline output stream. If a numeric argument is supplied,
the output is formatted in such a way that it can be made part
of an <VAR>inputrc</VAR> file. This command is unbound by default.
<P>
<A NAME="IDX172"></A>
<DT><CODE>dump-macros ()</CODE>
<DD><A NAME="IDX173"></A>
Print all of the Readline key sequences bound to macros and the
strings they output. If a numeric argument is supplied,
the output is formatted in such a way that it can be made part
of an <VAR>inputrc</VAR> file. This command is unbound by default.
<P>
<A NAME="IDX174"></A>
<DT><CODE>emacs-editing-mode (C-e)</CODE>
<DD><A NAME="IDX175"></A>
When in <CODE>vi</CODE> command mode, this causes a switch to <CODE>emacs</CODE>
editing mode.
<P>
<A NAME="IDX176"></A>
<DT><CODE>vi-editing-mode (M-C-j)</CODE>
<DD><A NAME="IDX177"></A>
When in <CODE>emacs</CODE> editing mode, this causes a switch to <CODE>vi</CODE>
editing mode.
<P>
</DL>
<P>
<A NAME="Readline vi Mode"></A>
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<H2> 1.5 Readline vi Mode </H2>
<!--docid::SEC22::-->
<P>
While the Readline library does not have a full set of <CODE>vi</CODE>
editing functions, it does contain enough to allow simple editing
of the line. The Readline <CODE>vi</CODE> mode behaves as specified in
the POSIX 1003.2 standard.
</P><P>
In order to switch interactively between <CODE>emacs</CODE> and <CODE>vi</CODE>
editing modes, use the command <KBD>M-C-j</KBD> (bound to emacs-editing-mode
when in <CODE>vi</CODE> mode and to vi-editing-mode in <CODE>emacs</CODE> mode).
The Readline default is <CODE>emacs</CODE> mode.
</P><P>
When you enter a line in <CODE>vi</CODE> mode, you are already placed in
`insertion' mode, as if you had typed an <SAMP>`i'</SAMP>. Pressing <KBD>ESC</KBD>
switches you into `command' mode, where you can edit the text of the
line with the standard <CODE>vi</CODE> movement keys, move to previous
history lines with <SAMP>`k'</SAMP> and subsequent lines with <SAMP>`j'</SAMP>, and
so forth.
</P><P>
This document describes the GNU Readline Library, a utility for aiding
in the consistency of user interface across discrete programs that need
to provide a command line interface.
</P><P>
Copyright (C) 1988-2005 Free Software Foundation, Inc.
</P><P>
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
pare preserved on all copies.
</P><P>
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.
</P><P>
Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation approved
by the Foundation.
</P><P>
<A NAME="Programming with GNU Readline"></A>
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</TR></TABLE>
<H1> 2. Programming with GNU Readline </H1>
<!--docid::SEC23::-->
<P>
This chapter describes the interface between the GNU Readline Library and
other programs. If you are a programmer, and you wish to include the
features found in GNU Readline
such as completion, line editing, and interactive history manipulation
in your own programs, this section is for you.
</P><P>
<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC24">2.1 Basic Behavior</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Using the default behavior of Readline.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC25">2.2 Custom Functions</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Adding your own functions to Readline.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC28">2.3 Readline Variables</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Variables accessible to custom
functions.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC29">2.4 Readline Convenience Functions</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Functions which Readline supplies to
aid in writing your own custom
functions.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC43">2.5 Readline Signal Handling</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">How Readline behaves when it receives signals.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC44">2.6 Custom Completers</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Supplanting or supplementing Readline's
completion functions.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>
<A NAME="Basic Behavior"></A>
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</TR></TABLE>
<H2> 2.1 Basic Behavior </H2>
<!--docid::SEC24::-->
<P>
Many programs provide a command line interface, such as <CODE>mail</CODE>,
<CODE>ftp</CODE>, and <CODE>sh</CODE>. For such programs, the default behaviour of
Readline is sufficient. This section describes how to use Readline in
the simplest way possible, perhaps to replace calls in your code to
<CODE>gets()</CODE> or <CODE>fgets()</CODE>.
</P><P>
<A NAME="IDX178"></A>
<A NAME="IDX179"></A>
</P><P>
The function <CODE>readline()</CODE> prints a prompt <VAR>prompt</VAR>
and then reads and returns a single line of text from the user.
If <VAR>prompt</VAR> is <CODE>NULL</CODE> or the empty string, no prompt is displayed.
The line <CODE>readline</CODE> returns is allocated with <CODE>malloc()</CODE>;
the caller should <CODE>free()</CODE> the line when it has finished with it.
The declaration for <CODE>readline</CODE> in ANSI C is
</P><P>
<TABLE><tr><td>&nbsp;</td><td class=example><pre><CODE>char *readline (const char *<VAR>prompt</VAR>);</CODE>
</pre></td></tr></table></P><P>
So, one might say
<TABLE><tr><td>&nbsp;</td><td class=example><pre><CODE>char *line = readline ("Enter a line: ");</CODE>
</pre></td></tr></table>in order to read a line of text from the user.
The line returned has the final newline removed, so only the
text remains.
</P><P>
If <CODE>readline</CODE> encounters an <CODE>EOF</CODE> while reading the line, and the
line is empty at that point, then <CODE>(char *)NULL</CODE> is returned.
Otherwise, the line is ended just as if a newline had been typed.
</P><P>
If you want the user to be able to get at the line later, (with
<KBD>C-p</KBD> for example), you must call <CODE>add_history()</CODE> to save the
line away in a <EM>history</EM> list of such lines.
</P><P>
<TABLE><tr><td>&nbsp;</td><td class=example><pre><CODE>add_history (line)</CODE>;
</pre></td></tr></table></P><P>
For full details on the GNU History Library, see the associated manual.
</P><P>
It is preferable to avoid saving empty lines on the history list, since
users rarely have a burning need to reuse a blank line. Here is
a function which usefully replaces the standard <CODE>gets()</CODE> library
function, and has the advantage of no static buffer to overflow:
</P><P>
<TABLE><tr><td>&nbsp;</td><td class=example><pre>/* A static variable for holding the line. */
static char *line_read = (char *)NULL;
/* Read a string, and return a pointer to it.
Returns NULL on EOF. */
char *
rl_gets ()
{
/* If the buffer has already been allocated,
return the memory to the free pool. */
if (line_read)
{
free (line_read);
line_read = (char *)NULL;
}
/* Get a line from the user. */
line_read = readline ("");
/* If the line has any text in it,
save it on the history. */
if (line_read &#38;&#38; *line_read)
add_history (line_read);
return (line_read);
}
</pre></td></tr></table></P><P>
This function gives the user the default behaviour of <KBD>TAB</KBD>
completion: completion on file names. If you do not want Readline to
complete on filenames, you can change the binding of the <KBD>TAB</KBD> key
with <CODE>rl_bind_key()</CODE>.
</P><P>
<TABLE><tr><td>&nbsp;</td><td class=example><pre><CODE>int rl_bind_key (int <VAR>key</VAR>, rl_command_func_t *<VAR>function</VAR>);</CODE>
</pre></td></tr></table></P><P>
<CODE>rl_bind_key()</CODE> takes two arguments: <VAR>key</VAR> is the character that
you want to bind, and <VAR>function</VAR> is the address of the function to
call when <VAR>key</VAR> is pressed. Binding <KBD>TAB</KBD> to <CODE>rl_insert()</CODE>
makes <KBD>TAB</KBD> insert itself.
<CODE>rl_bind_key()</CODE> returns non-zero if <VAR>key</VAR> is not a valid
ASCII character code (between 0 and 255).
</P><P>
Thus, to disable the default <KBD>TAB</KBD> behavior, the following suffices:
<TABLE><tr><td>&nbsp;</td><td class=example><pre><CODE>rl_bind_key ('\t', rl_insert);</CODE>
</pre></td></tr></table></P><P>
This code should be executed once at the start of your program; you
might write a function called <CODE>initialize_readline()</CODE> which
performs this and other desired initializations, such as installing
custom completers (see section <A HREF="readline.html#SEC44">2.6 Custom Completers</A>).
</P><P>
<A NAME="Custom Functions"></A>
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<H2> 2.2 Custom Functions </H2>
<!--docid::SEC25::-->
<P>
Readline provides many functions for manipulating the text of
the line, but it isn't possible to anticipate the needs of all
programs. This section describes the various functions and variables
defined within the Readline library which allow a user program to add
customized functionality to Readline.
</P><P>
Before declaring any functions that customize Readline's behavior, or
using any functionality Readline provides in other code, an
application writer should include the file <CODE>&#60;readline/readline.h&#62;</CODE>
in any file that uses Readline's features. Since some of the definitions
in <CODE>readline.h</CODE> use the <CODE>stdio</CODE> library, the file
<CODE>&#60;stdio.h&#62;</CODE> should be included before <CODE>readline.h</CODE>.
</P><P>
<CODE>readline.h</CODE> defines a C preprocessor variable that should
be treated as an integer, <CODE>RL_READLINE_VERSION</CODE>, which may
be used to conditionally compile application code depending on
the installed Readline version. The value is a hexadecimal
encoding of the major and minor version numbers of the library,
of the form 0x<VAR>MMmm</VAR>. <VAR>MM</VAR> is the two-digit major
version number; <VAR>mm</VAR> is the two-digit minor version number.
For Readline 4.2, for example, the value of
<CODE>RL_READLINE_VERSION</CODE> would be <CODE>0x0402</CODE>.
</P><P>
<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC26">2.2.1 Readline Typedefs</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">C declarations to make code readable.</TD></TR>
<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="readline.html#SEC27">2.2.2 Writing a New Function</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Variables and calling conventions.</TD></TR>
</TABLE></BLOCKQUOTE>
<P>
<A NAME="Readline Typedefs"></A>
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</TR></TABLE>
<H3> 2.2.1 Readline Typedefs </H3>
<!--docid::SEC26::-->
<P>
For readabilty, we declare a number of new object types, all pointers
to functions.
</P><P>
The reason for declaring these new types is to make it easier to write
code describing pointers to C functions with appropriately prototyped
arguments and return values.
</P><P>
For instance, say we want to declare a variable <VAR>func</VAR> as a pointer
to a function which takes two <CODE>int</CODE> arguments and returns an
<CODE>int</CODE> (this is the type of all of the Readline bindable functions).
Instead of the classic C declaration
</P><P>
<CODE>int (*func)();</CODE>
</P><P>
or the ANSI-C style declaration
</P><P>
<CODE>int (*func)(int, int);</CODE>
</P><P>
we may write
</P><P>
<CODE>rl_command_func_t *func;</CODE>
</P><P>
The full list of function pointer types available is
</P><P>
<DL COMPACT>
<DT><CODE>typedef int rl_command_func_t (int, int);</CODE>
<DD><P>
<DT><CODE>typedef char *rl_compentry_func_t (const char *, int);</CODE>
<DD><P>
<DT><CODE>typedef char **rl_completion_func_t (const char *, int, int);</CODE>
<DD><P>
<DT><CODE>typedef char *rl_quote_func_t (char *, int, char *);</CODE>
<DD><P>
<DT><CODE>typedef char *rl_dequote_func_t (char *, int);</CODE>
<DD><P>
<DT><CODE>typedef int rl_compignore_func_t (char **);</CODE>
<DD><P>
<DT><CODE>typedef void rl_compdisp_func_t (char **, int, int);</CODE>
<DD><P>
<DT><CODE>typedef int rl_hook_func_t (void);</CODE>
<DD><P>
<DT><CODE>typedef int rl_getc_func_t (FILE *);</CODE>
<DD><P>
<DT><CODE>typedef int rl_linebuf_func_t (char *, int);</CODE>
<DD><P>
<DT><CODE>typedef int rl_intfunc_t (int);</CODE>
<DD><DT><CODE>#define rl_ivoidfunc_t rl_hook_func_t</CODE>
<DD><DT><CODE>typedef int rl_icpfunc_t (char *);</CODE>
<DD><DT><CODE>typedef int rl_icppfunc_t (char **);</CODE>
<DD><P>
<DT><CODE>typedef void rl_voidfunc_t (void);</CODE>
<DD><DT><CODE>typedef void rl_vintfunc_t (int);</CODE>
<DD><DT><CODE>typedef void rl_vcpfunc_t (char *);</CODE>
<DD><DT><CODE>typedef void rl_vcppfunc_t (char **);</CODE>
<DD><P>
</DL>
<P>
<A NAME="Function Writing"></A>
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</TR></TABLE>
<H3> 2.2.2 Writing a New Function </H3>
<!--docid::SEC27::-->
<P>
In order to write new functions for Readline, you need to know the
calling conventions for keyboard-invoked functions, and the names of the
variables that describe the current state of the line read so far.
</P><P>
The calling sequence for a command <CODE>foo</CODE> looks like
</P><P>
<TABLE><tr><td>&nbsp;</td><td class=example><pre><CODE>int foo (int count, int key)</CODE>
</pre></td></tr></table></P><P>
where <VAR>count</VAR> is the numeric argument (or 1 if defaulted) and
<VAR>key</VAR> is the key that invoked this function.
</P><P>
It is completely up to the function as to what should be done with the
numeric argument. Some functions use it as a repeat count, some
as a flag, and others to choose alternate behavior (refreshing the current
line as opposed to refreshing the screen, for example). Some choose to
ignore it. In general, if a
function uses the numeric argument as a repeat count, it should be able
to do something useful with both negative and positive arguments.
At the very least, it should be aware that it can be passed a
negative argument.
</P><P>
A command function should return 0 if its action completes successfully,
and a non-zero value if some error occurs.
This is the convention obeyed by all of the builtin Readline bindable
command functions.
</P><P>
<A NAME="Readline Variables"></A>
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</TR></TABLE>
<H2> 2.3 Readline Variables </H2>
<!--docid::SEC28::-->
<P>
These variables are available to function writers.
</P><P>
<A NAME="IDX180"></A>
<DL>
<DT><U>Variable:</U> char * <B>rl_line_buffer</B>
<DD>This is the line gathered so far. You are welcome to modify the
contents of the line, but see <A HREF="readline.html#SEC34">2.4.5 Allowing Undoing</A>. The
function <CODE>rl_extend_line_buffer</CODE> is available to increase
the memory allocated to <CODE>rl_line_buffer</CODE>.
</DL>
</P><P>
<A NAME="IDX181"></A>
<DL>
<DT><U>Variable:</U> int <B>rl_point</B>
<DD>The offset of the current cursor position in <CODE>rl_line_buffer</CODE>
(the <EM>point</EM>).
</DL>
</P><P>
<A NAME="IDX182"></A>
<DL>
<DT><U>Variable:</U> int <B>rl_end</B>
<DD>The number of characters present in <CODE>rl_line_buffer</CODE>. When
<CODE>rl_point</CODE> is at the end of the line, <CODE>rl_point</CODE> and
<CODE>rl_end</CODE> are equal.
</DL>
</P><P>
<A NAME="IDX183"></A>
<DL>
<DT><U>Variable:</U> int <B>rl_mark</B>
<DD>The <VAR>mark</VAR> (saved position) in the current line. If set, the mark
and point define a <EM>region</EM>.
</DL>
</P><P>
<A NAME="IDX184"></A>
<DL>
<DT><U>Variable:</U> int <B>rl_done</B>
<DD>Setting this to a non-zero value causes Readline to return the current
line immediately.
</DL>
</P><P>
<A NAME="IDX185"></A>
<DL>
<DT><U>Variable:</U> int <B>rl_num_chars_to_read</B>
<DD>Setting this to a positive value before calling <CODE>readline()</CODE> causes
Readline to return after accepting that many characters, rather
than reading up to a character bound to <CODE>accept-line</CODE>.
</DL>
</P><P>
<A NAME="IDX186"></A>
<DL>
<DT><U>Variable:</U> int <B>rl_pending_input</B>
<DD>Setting this to a value makes it the next keystroke read. This is a
way to stuff a single character into the input stream.
</DL>
</P><P>
<A NAME="IDX187"></A>
<DL>
<DT><U>Variable:</U> int <B>rl_dispatching</B>
<DD>Set to a non-zero value if a function is being called from a key binding;
zero otherwise. Application functions can test this to discover whether
they were called directly or by Readline's dispatching mechanism.
</DL>
</P><P>
<A NAME="IDX188"></A>
<DL>
<DT><U>Variable:</U> int <B>rl_erase_empty_line</B>
<DD>Setting this to a non-zero value causes Readline to completely erase
the current line, including any prompt, any time a newline is typed as
the only character on an otherwise-empty line. The cursor is moved to
the beginning of the newly-blank line.
</DL>
</P><P>
<A NAME="IDX189"></A>