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Info file readline.info, produced by Makeinfo, -*- Text -*- from input
file rlman.texinfo.
This document describes the GNU Readline Library, a utility which
aids in the consistency of user interface across discrete programs
that need to provide a command line interface.
Copyright (C) 1988, 1991 Free Software Foundation, Inc.
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.
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.
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.

File: readline.info, Node: Top, Next: Command Line Editing, Prev: (DIR), Up: (DIR)
GNU Readline Library
********************
This document describes the GNU Readline Library, a utility which
aids in the consistency of user interface across discrete programs
that need to provide a command line interface.
* Menu:
* Command Line Editing:: GNU Readline User's Manual.
* Programming with GNU Readline:: GNU Readline Programmer's Manual.
* Concept Index:: Index of concepts described in this manual.
* Function and Variable Index:: Index of externally visible functions
and variables.

File: readline.info, Node: Command Line Editing, Next: Programming with GNU Readline, Prev: Top, Up: Top
Command Line Editing
********************
This text describes GNU's command line editing interface.
* Menu:
* Introduction and Notation:: Notation used in this text.
* Readline Interaction:: The minimum set of commands for editing a line.
* Readline Init File:: Customizing Readline from a user's view.

File: readline.info, Node: Introduction and Notation, Next: Readline Interaction, Up: Command Line Editing
Introduction to Line Editing
============================
The following paragraphs describe the notation we use to represent
keystrokes.
The text C-k is read as `Control-K' and describes the character
produced when the Control key is depressed and the k key is struck.
The text M-k is read as `Meta-K' and describes the character
produced when the meta key (if you have one) is depressed, and the k
key is struck. If you do not have a meta key, the identical keystroke
can be generated by typing ESC first, and then typing k. Either
process is known as "metafying" the k key.
The text M-C-k is read as `Meta-Control-k' and describes the
character produced by "metafying" C-k.
In addition, several keys have their own names. Specifically, DEL,
ESC, LFD, SPC, RET, and TAB all stand for themselves when seen in this
text, or in an init file (*note Readline Init File::., for more info).

File: readline.info, Node: Readline Interaction, Next: Readline Init File, Prev: Introduction and Notation, Up: Command Line Editing
Readline Interaction
====================
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 RETURN. You do not have to be at the end
of the line to press RETURN; the entire line is accepted regardless of
the location of the cursor within the line.
* Menu:
* Readline Bare Essentials:: The least you need to know about Readline.
* Readline Movement Commands:: Moving about the input line.
* Readline Killing Commands:: How to delete text, and how to get it back!
* Readline Arguments:: Giving numeric arguments to commands.

File: readline.info, Node: Readline Bare Essentials, Next: Readline Movement Commands, Up: Readline Interaction
Readline Bare Essentials
------------------------
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
DEL to back up, and delete the mistyped character.
Sometimes you may miss typing a character that you wanted to type,
and not notice your error until you have typed several other
characters. In that case, you can type C-b to move the cursor to the
left, and then correct your mistake. Aftwerwards, you can move the
cursor to the right with C-f.
When you add text in the middle of a line, you will notice that
characters to the right of the cursor get `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 get `pulled
back' to fill in the blank space created by the removal of the text.
A list of the basic bare essentials for editing the text of an input
line follows.
C-b
Move back one character.
C-f
Move forward one character.
DEL
Delete the character to the left of the cursor.
C-d
Delete the character underneath the cursor.
Printing characters
Insert itself into the line at the cursor.
C-_
Undo the last thing that you did. You can undo all the way back
to an empty line.

File: readline.info, Node: Readline Movement Commands, Next: Readline Killing Commands, Prev: Readline Bare Essentials, Up: Readline Interaction
Readline Movement Commands
--------------------------
The above table describes the most basic possible 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 C-b,
C-f, C-d, and DEL. Here are some commands for moving more rapidly
about the line.
C-a
Move to the start of the line.
C-e
Move to the end of the line.
M-f
Move forward a word.
M-b
Move backward a word.
C-l
Clear the screen, reprinting the current line at the top.
Notice how C-f moves forward a character, while M-f moves forward a
word. It is a loose convention that control keystrokes operate on
characters while meta keystrokes operate on words.

File: readline.info, Node: Readline Killing Commands, Next: Readline Arguments, Prev: Readline Movement Commands, Up: Readline Interaction
Readline Killing Commands
-------------------------
The act of "cutting" text means to delete the text from the line,
and to save away the deleted text for later use, just as if you had
cut the text out of the line with a pair of scissors. There is a
"Killing" text means to delete the text from the line, but to save
it away for later use, usually by "yanking" it back into the line. 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.
Here is the list of commands for killing text.
C-k
Kill the text from the current cursor position to the end of the
line.
M-d
Kill from the cursor to the end of the current word, or if between
words, to the end of the next word.
M-DEL
Kill fromthe cursor the start of the previous word, or if between
words, to the start of the previous word.
C-w
Kill from the cursor to the previous whitespace. This is
different than M-DEL because the word boundaries differ.
And, here is how to "yank" the text back into the line. Yanking is
C-y
Yank the most recently killed text back into the buffer at the
cursor.
M-y
Rotate the kill-ring, and yank the new top. You can only do this
if the prior command is C-y or M-y.
When you use a kill command, the text is saved in a "kill-ring".
Any number of consecutive kills save all of the killed text together,
so that when you yank it back, you get it in one clean sweep. 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.

File: readline.info, Node: Readline Arguments, Prev: Readline Killing Commands, Up: Readline Interaction
Readline Arguments
------------------
You can pass numeric arguments to Readline commands. Sometimes the
argument acts as a repeat count, other times it is the sign 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 M-- C-k.
The general way to pass numeric arguments to a command is to type
meta digits before the command. If the first `digit' you type is a
minus sign (-), 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 C-d command an argument of 10, you could type M-1 0 C-d.

File: readline.info, Node: Readline Init File, Prev: Readline Interaction, Up: Command Line Editing
Readline Init File
==================
Although the Readline library comes with a set of Emacs-like
keybindings, it is possible that you would like to use a different set
of keybindings. You can customize programs that use Readline by
putting commands in an "init" file in your home directory. The name
of this file is `~/.inputrc'.
When a program which uses the Readline library starts up, the
`~/.inputrc' file is read, and the keybindings are set.
In addition, the `C-x C-r' command re-reads this init file, thus
incorporating any changes that you might have made to it.
* Menu:
* Readline Init Syntax:: Syntax for the commands in `~/.inputrc'.
* Readline Vi Mode:: Switching to `vi' mode in Readline.

File: readline.info, Node: Readline Init Syntax, Next: Readline Vi Mode, Up: Readline Init File
Readline Init Syntax
--------------------
There are only four constructs allowed in the `~/.inputrc' file:
Variable Settings
You can change the state of a few variables in Readline. You do
this by using the `set' command within the init file. Here is
how you would specify that you wish to use Vi line editing
commands:
set editing-mode vi
Right now, there are only a few variables which can be set; so
few in fact, that we just iterate them here:
`editing-mode'
The `editing-mode' variable controls which editing mode you
are using. By default, GNU Readline starts up in Emacs
editing mode, where the keystrokes are most similar to
Emacs. This variable can either be set to `emacs' or `vi'.
`horizontal-scroll-mode'
This variable can either be set to `On' or `Off'. Setting it
to `On' means that the text of the lines that you edit will
scroll horizontally on a single screen line when they are
larger than the width of the screen, instead of wrapping
onto a new screen line. By default, this variable is set to
`Off'.
`mark-modified-lines'
This variable when set to `On', says to display an asterisk
(`*') at the starts of history lines which have been
modified. This variable is off by default.
`prefer-visible-bell'
If this variable is set to `On' it means to use a visible
bell if one is available, rather than simply ringing the
terminal bell. By default, the value is `Off'.
Key Bindings
The syntax for controlling keybindings in the `~/.inputrc' file is
simple. First you have to know the name of the command that you
want to change. The following pages contain tables of the
command name, the default keybinding, and a short description of
what the command does.
Once you know the name of the command, simply place the name of
the key you wish to bind the command to, a colon, and then the
name of the command on a line in the `~/.inputrc' file. The name
of the key can be expressed in different ways, depending on which
is most comfortable for you.
KEYNAME: FUNCTION-NAME or MACRO
KEYNAME is the name of a key spelled out in English. For
example:
Control-u: universal-argument
Meta-Rubout: backward-kill-word
Control-o: ">&output"
In the above example, `C-u' is bound to the function
`universal-argument', and `C-o' is bound to run the macro
expressed on the right hand side (that is, to insert the text
`>&output' into the line).
"KEYSEQ": FUNCTION-NAME or MACRO
KEYSEQ differs from KEYNAME above in that strings denoting
an entire key sequence can be specified. Simply place the
key sequence in double quotes. GNU Emacs style key escapes
can be used, as in the following example:
"\C-u": universal-argument
"\C-x\C-r": re-read-init-file
"\e[11~": "Function Key 1"
In the above example, `C-u' is bound to the function
`universal-argument' (just as it was in the first example),
`C-x C-r' is bound to the function `re-read-init-file', and
`ESC [ 1 1 ~' is bound to insert the text `Function Key 1'.
* Menu:
* Commands For Moving:: Moving about the line.
* Commands For History:: Getting at previous lines.
* Commands For Text:: Commands for changing text.
* Commands For Killing:: Commands for killing and yanking.
* Numeric Arguments:: Specifying numeric arguments, repeat counts.
* Commands For Completion:: Getting Readline to do the typing for you.
* Miscellaneous Commands:: Other miscillaneous commands.

File: readline.info, Node: Commands For Moving, Next: Commands For History, Up: Readline Init Syntax
Commands For Moving
...................
`beginning-of-line (C-a)'
Move to the start of the current line.
`end-of-line (C-e)'
Move to the end of the line.
`forward-char (C-f)'
Move forward a character.
`backward-char (C-b)'
Move back a character.
`forward-word (M-f)'
Move forward to the end of the next word.
`backward-word (M-b)'
Move back to the start of this, or the previous, word.
`clear-screen (C-l)'
Clear the screen leaving the current line at the top of the
screen.

File: readline.info, Node: Commands For History, Next: Commands For Text, Prev: Commands For Moving, Up: Readline Init Syntax
Commands For Manipulating The History
.....................................
`accept-line (Newline, Return)'
Accept the line regardless of where the cursor is. If this line
is non-empty, add it to the history list. If this line was a
history line, then restore the history line to its original state.
`previous-history (C-p)'
Move `up' through the history list.
`next-history (C-n)'
Move `down' through the history list.
`beginning-of-history (M-<)'
Move to the first line in the history.
`end-of-history (M->)'
Move to the end of the input history, i.e., the line you are
entering!
`reverse-search-history (C-r)'
Search backward starting at the current line and moving `up'
through the history as necessary. This is an incremental search.
`forward-search-history (C-s)'
Search forward starting at the current line and moving `down'
through the the history as neccessary.

File: readline.info, Node: Commands For Text, Next: Commands For Killing, Prev: Commands For History, Up: Readline Init Syntax
Commands For Changing Text
..........................
`delete-char (C-d)'
Delete the character under the cursor. If the cursor is at the
beginning of the line, and there are no characters in the line,
and the last character typed was not C-d, then return EOF.
`backward-delete-char (Rubout)'
Delete the character behind the cursor. A numeric arg says to
kill the characters instead of deleting them.
`quoted-insert (C-q, C-v)'
Add the next character that you type to the line verbatim. This
is how to insert things like C-q for example.
`tab-insert (M-TAB)'
Insert a tab character.
`self-insert (a, b, A, 1, !, ...)'
Insert yourself.
`transpose-chars (C-t)'
Drag the character before point forward over the character at
point. Point moves forward as well. If point is at the end of
the line, then transpose the two characters before point.
Negative args don't work.
`transpose-words (M-t)'
Drag the word behind the cursor past the word in front of the
cursor moving the cursor over that word as well.
`upcase-word (M-u)'
Uppercase the current (or following) word. With a negative
argument, do the previous word, but do not move point.
`downcase-word (M-l)'
Lowercase the current (or following) word. With a negative
argument, do the previous word, but do not move point.
`capitalize-word (M-c)'
Uppercase the current (or following) word. With a negative
argument, do the previous word, but do not move point.

File: readline.info, Node: Commands For Killing, Next: Numeric Arguments, Prev: Commands For Text, Up: Readline Init Syntax
Killing And Yanking
...................
`kill-line (C-k)'
Kill the text from the current cursor position to the end of the
line.
`backward-kill-line ()'
Kill backward to the beginning of the line. This is normally
unbound.
`kill-word (M-d)'
Kill from the cursor to the end of the current word, or if between
words, to the end of the next word.
`backward-kill-word (M-DEL)'
Kill the word behind the cursor.
`unix-line-discard (C-u)'
Do what C-u used to do in Unix line input. We save the killed
text on the kill-ring, though.
`unix-word-rubout (C-w)'
Do what C-w used to do in Unix line input. The killed text is
saved on the kill-ring. This is different than
backward-kill-word because the word boundaries differ.
`yank (C-y)'
Yank the top of the kill ring into the buffer at point.
`yank-pop (M-y)'
Rotate the kill-ring, and yank the new top. You can only do this
if the prior command is yank or yank-pop.

File: readline.info, Node: Numeric Arguments, Next: Commands For Completion, Prev: Commands For Killing, Up: Readline Init Syntax
Specifying Numeric Arguments
............................
`digit-argument (M-0, M-1, ... M--)'
Add this digit to the argument already accumulating, or start a
new argument. M-- starts a negative argument.
`universal-argument ()'
Do what C-u does in emacs. By default, this is not bound.

File: readline.info, Node: Commands For Completion, Next: Miscellaneous Commands, Prev: Numeric Arguments, Up: Readline Init Syntax
Letting Readline Type For You
.............................
`complete (TAB)'
Attempt to do completion on the text before point. This is
implementation defined. Generally, if you are typing a filename
argument, you can do filename completion; if you are typing a
command, you can do command completion, if you are typing in a
symbol to GDB, you can do symbol name completion, if you are
typing in a variable to Bash, you can do variable name
completion...
`possible-completions (M-?)'
List the possible completions of the text before point.

File: readline.info, Node: Miscellaneous Commands, Prev: Commands For Completion, Up: Readline Init Syntax
Some Miscellaneous Commands
...........................
`re-read-init-file (C-x C-r)'
Read in the contents of your `~/.inputrc' file, and incorporate
any bindings found there.
`abort (C-g)'
Ding! Stops things.
`do-uppercase-version (M-a, M-b, ...)'
Run the command that is bound to your uppercase brother.
`prefix-meta (ESC)'
Make the next character that you type be metafied. This is for
people without a meta key. Typing `ESC f' is equivalent to typing
`M-f'.
`undo (C-_)'
Incremental undo, separately remembered for each line.
`revert-line (M-r)'
Undo all changes made to this line. This is like typing the
`undo' command enough times to get back to the beginning.

File: readline.info, Node: Readline Vi Mode, Prev: Readline Init Syntax, Up: Readline Init File
Readline Vi Mode
----------------
While the Readline library does not have a full set of Vi editing
functions, it does contain enough to allow simple editing of the line.
In order to switch interactively between Emacs and Vi editing
modes, use the command M-C-j (toggle-editing-mode).
When you enter a line in Vi mode, you are already placed in
`insertion' mode, as if you had typed an `i'. Pressing ESC switches
you into `edit' mode, where you can edit the text of the line with the
standard Vi movement keys, move to previous history lines with `k',
and following lines with `j', and so forth.
This document describes the GNU Readline Library, a utility for
aiding in the consitency of user interface across discrete programs
that need to provide a command line interface.
Copyright (C) 1988 Free Software Foundation, Inc.
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.
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.
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.

File: readline.info, Node: Programming with GNU Readline, Next: Concept Index, Prev: Command Line Editing, Up: Top
Programming with GNU Readline
*****************************
This manual describes the interface between the GNU Readline
Library and user programs. If you are a programmer, and you wish to
include the features found in GNU Readline in your own programs, such
as completion, line editing, and interactive history manipulation,
this documentation is for you.
* Menu:
* Default Behaviour:: Using the default behaviour of Readline.
* Custom Functions:: Adding your own functions to Readline.
* Custom Completers:: Supplanting or supplementing Readline's
completion functions.

File: readline.info, Node: Default Behaviour, Next: Custom Functions, Up: Programming with GNU Readline
Default Behaviour
=================
Many programs provide a command line interface, such as `mail',
`ftp', and `sh'. 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 `gets
()'.
The function `readline' prints a prompt and then reads and returns
a single line of text from the user. The line which `readline ()'
returns is allocated with `malloc ()'; you should `free ()' the line
when you are done with it. The declaration for `readline' in ANSI C is
`char *readline (char *PROMPT);'
So, one might say
`char *line = readline ("Enter a line: ");'
in order to read a line of text from the user.
The line which is returned has the final newline removed, so only
the text of the line remains.
If readline encounters an `EOF' while reading the line, and the
line is empty at that point, then `(char *)NULL' is returned.
Otherwise, the line is ended just as if a newline was typed.
If you want the user to be able to get at the line later, (with C-p
for example), you must call `add_history ()' to save the line away in
a "history" list of such lines.
`add_history (line)';
For full details on the GNU History Library, see the associated
manual.
It is polite to avoid saving empty lines on the history list, since
it is rare than someone has a burning need to reuse a blank line.
Here is a function which usefully replaces the standard `gets ()'
library function:
/* 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 *
do_gets ()
{
/* If the buffer has already been allocated, return the memory
to the free pool. */
if (line_read != (char *)NULL)
{
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 && *line_read)
add_history (line_read);
return (line_read);
}
The above code gives the user the default behaviour of TAB
completion: completion on file names. If you do not want readline to
complete on filenames, you can change the binding of the TAB key with
`rl_bind_key ()'.
`int rl_bind_key (int KEY, (int (*)())FUNCTION);'
`rl_bind_key ()' takes 2 arguments; KEY is the character that you
want to bind, and FUNCTION is the address of the function to run when
KEY is pressed. Binding TAB to `rl_insert ()' makes TAB just insert
itself.
`rl_bind_key ()' returns non-zero if KEY is not a valid ASCII
character code (between 0 and 255).
`rl_bind_key ('\t', rl_insert);'
This code should be executed once at the start of your program; you
might write a function called `initialize_readline ()' which performs
this and other desired initializations, such as installing custom
completers, etc.

File: readline.info, Node: Custom Functions, Next: Custom Completers, Prev: Default Behaviour, Up: Programming with GNU Readline
Custom Functions
================
Readline provides a great 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 in within the Readline library which allow a user program to
add customized functionality to Readline.
* Menu:
* The Function Type:: C declarations to make code readable.
* Function Naming:: How to give a function you write a name.
* Keymaps:: Making keymaps.
* Binding Keys:: Changing Keymaps.
* Function Writing:: Variables and calling conventions.
* Allowing Undoing:: How to make your functions undoable.

File: readline.info, Node: The Function Type, Next: Function Naming, Up: Custom Functions
The Function Type
-----------------
For the sake of readabilty, we declare a new type of object, called
"Function". A `Function' is a C language function which returns an
`int'. The type declaration for `Function' is:
`typedef int Function ();'
The reason for declaring this new type is to make it easier to write
code describing pointers to C functions. Let us say we had a variable
called FUNC which was a pointer to a function. Instead of the classic
C declaration
`int (*)()func;'
we have
`Function *func;'

File: readline.info, Node: Function Naming, Next: Keymaps, Prev: The Function Type, Up: Custom Functions
Naming a Function
-----------------
The user can dynamically change the bindings of keys while using
Readline. This is done by representing the function with a descriptive
name. The user is able to type the descriptive name when referring to
the function. Thus, in an init file, one might find
Meta-Rubout: backward-kill-word
This binds the keystroke Meta-Rubout to the function
*descriptively* named `backward-kill-word'. You, as the programmer,
should bind the functions you write to descriptive names as well.
Readline provides a function for doing that:
* Function: rl_add_defun (CHAR *NAME, FUNCTION *FUNCTION, INT KEY)
Add NAME to the list of named functions. Make FUNCTION be the
function that gets called. If KEY is not -1, then bind it to
FUNCTION using `rl_bind_key ()'.
Using this function alone is sufficient for most applications. It
is the recommended way to add a few functions to the default functions
that Readline has built in already. If you need to do more or
different things than adding a function to Readline, you may need to
use the underlying functions described below.

File: readline.info, Node: Keymaps, Next: Binding Keys, Prev: Function Naming, Up: Custom Functions
Selecting a Keymap
------------------
Key bindings take place on a "keymap". The keymap is the
association between the keys that the user types and the functions that
get run. You can make your own keymaps, copy existing keymaps, and
tell Readline which keymap to use.
* Function: Keymap rl_make_bare_keymap ()
Returns a new, empty keymap. The space for the keymap is
allocated with `malloc ()'; you should `free ()' it when you are
done.
* Function: Keymap rl_copy_keymap (KEYMAP MAP)
Return a new keymap which is a copy of MAP.
* Function: Keymap rl_make_keymap ()
Return a new keymap with the printing characters bound to
rl_insert, the lowercase Meta characters bound to run their
equivalents, and the Meta digits bound to produce numeric
arguments.

File: readline.info, Node: Binding Keys, Next: Function Writing, Prev: Keymaps, Up: Custom Functions
Binding Keys
------------
You associate keys with functions through the keymap. Here are
functions for doing that.
* Function: int rl_bind_key (INT KEY, FUNCTION *FUNCTION)
Binds KEY to FUNCTION in the currently selected keymap. Returns
non-zero in the case of an invalid KEY.
* Function: int rl_bind_key_in_map (INT KEY, FUNCTION *FUNCTION,
KEYMAP MAP)
Bind KEY to FUNCTION in MAP. Returns non-zero in the case of an
invalid KEY.
* Function: int rl_unbind_key (INT KEY)
Make KEY do nothing in the currently selected keymap. Returns
non-zero in case of error.
* Function: int rl_unbind_key_in_map (INT KEY, KEYMAP MAP)
Make KEY be bound to the null function in MAP. Returns non-zero
in case of error.
* Function: rl_generic_bind (INT TYPE, CHAR *KEYSEQ, CHAR *DATA,
KEYMAP MAP)
Bind the key sequence represented by the string KEYSEQ to the
arbitrary pointer DATA. TYPE says what kind of data is pointed
to by DATA; right now this can be a function (`ISFUNC'), a macro
(`ISMACR'), or a keymap (`ISKMAP'). This makes new keymaps as
necessary. The initial place to do bindings is in MAP.

File: readline.info, Node: Function Writing, Next: Allowing Undoing, Prev: Binding Keys, Up: Custom Functions
Writing a New Function
----------------------
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 gathered so
far.
* Variable: char *rl_line_buffer
This is the line gathered so far. You are welcome to modify the
contents of this, but see Undoing, below.
* Variable: int rl_point
The offset of the current cursor position in RL_LINE_BUFFER.
* Variable: int rl_end
The number of characters present in `rl_line_buffer'. When
`rl_point' is at the end of the line, then `rl_point' and
`rl_end' are equal.
The calling sequence for a command `foo' looks like
`foo (int count, int key)'
where COUNT is the numeric argument (or 1 if defaulted) and KEY is
the key that invoked this function.
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, other
functions as a flag, and 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 a negative argument as well as a positive
argument. At the very least, it should be aware that it can be passed
a negative argument.

File: readline.info, Node: Allowing Undoing, Prev: Function Writing, Up: Custom Functions
Allowing Undoing
----------------
Supporting the undo command is a painless thing to do, and makes
your functions much more useful to the end user. It is certainly easy
to try something if you know you can undo it. I could use an undo
function for the stock market.
If your function simply inserts text once, or deletes text once,
and it calls `rl_insert_text ()' or `rl_delete_text ()' to do it, then
undoing is already done for you automatically, and you can safely skip
this section.
If you do multiple insertions or multiple deletions, or any
combination of these operations, you should group them together into
one operation. This can be done with `rl_begin_undo_group ()' and
`rl_end_undo_group ()'.
* Function: rl_begin_undo_group ()
Begins saving undo information in a group construct. The undo
information usually comes from calls to `rl_insert_text ()' and
`rl_delete_text ()', but they could be direct calls to
`rl_add_undo ()'.
* Function: rl_end_undo_group ()
Closes the current undo group started with `rl_begin_undo_group
()'. There should be exactly one call to `rl_end_undo_group ()'
for every call to `rl_begin_undo_group ()'.
Finally, if you neither insert nor delete text, but directly modify
the existing text (e.g. change its case), you call `rl_modifying ()'
once, just before you modify the text. You must supply the indices of
the text range that you are going to modify.
* Function: rl_modifying (INT START, INT END)
Tell Readline to save the text between START and END as a single
undo unit. It is assumed that subsequent to this call you will
modify that range of text in some way.
An Example
----------
Here is a function which changes lowercase characters to the
uppercase equivalents, and uppercase characters to the lowercase
equivalents. If this function was bound to `M-c', then typing `M-c'
would change the case of the character under point. Typing `10 M-c'
would change the case of the following 10 characters, leaving the
cursor on the last character changed.
/* Invert the case of the COUNT following characters. */
invert_case_line (count, key)
int count, key;
{
register int start, end;
start = rl_point;
if (count < 0)
{
direction = -1;
count = -count;
}
else
direction = 1;
/* Find the end of the range to modify. */
end = start + (count * direction);
/* Force it to be within range. */
if (end > rl_end)
end = rl_end;
else if (end < 0)
end = -1;
if (start > end)
{
int temp = start;
start = end;
end = temp;
}
if (start == end)
return;
/* Tell readline that we are modifying the line, so save the undo
information. */
rl_modifying (start, end);
for (; start != end; start += direction)
{
if (uppercase_p (rl_line_buffer[start]))
rl_line_buffer[start] = to_lower (rl_line_buffer[start]);
else if (lowercase_p (rl_line_buffer[start]))
rl_line_buffer[start] = to_upper (rl_line_buffer[start]);
}
/* Move point to on top of the last character changed. */
rl_point = end - direction;
}

File: readline.info, Node: Custom Completers, Prev: Custom Functions, Up: Programming with GNU Readline
Custom Completers
=================
Typically, a program that reads commands from the user has a way of
disambiguating commands and data. If your program is one of these,
then it can provide completion for either commands, or data, or both
commands and data. The following sections describe how your program
and Readline cooperate to provide this service to end users.
* Menu:
* How Completing Works:: The logic used to do completion.
* Completion Functions:: Functions provided by Readline.
* Completion Variables:: Variables which control completion.
* A Short Completion Example:: An example of writing completer subroutines.

File: readline.info, Node: How Completing Works, Next: Completion Functions, Up: Custom Completers
How Completing Works
--------------------
In order to complete some text, the full list of possible
completions must be available. That is to say, it is not possible to
accurately expand a partial word without knowing what all of the
possible words that make sense in that context are. The GNU Readline
library provides the user interface to completion, and additionally,
two of the most common completion functions; filename and username.
For completing other types of text, you must write your own completion
function. This section describes exactly what those functions must
do, and provides an example function.
There are three major functions used to perform completion:
1. The user-interface function `rl_complete ()'. This function is
called interactively with the same calling conventions as other
functions in readline intended for interactive use; i.e. COUNT,
and INVOKING-KEY. It isolates the word to be completed and calls
`completion_matches ()' to generate a list of possible
completions. It then either lists the possible completions or
actually performs the completion, depending on which behaviour is
desired.
2. The internal function `completion_matches ()' uses your
"generator" function to generate the list of possible matches, and
then returns the array of these matches. You should place the
address of your generator function in
`rl_completion_entry_function'.
3. The generator function is called repeatedly from
`completion_matches ()', returning a string each time. The
arguments to the generator function are TEXT and STATE. TEXT is
the partial word to be completed. STATE is zero the first time
the function is called, and a positive non-zero integer for each
subsequent call. When the generator function returns `(char
*)NULL' this signals `completion_matches ()' that there are no
more possibilities left.
* Function: rl_complete (INT IGNORE, INT INVOKING_KEY)
Complete the word at or before point. You have supplied the
function that does the initial simple matching selection
algorithm (see `completion_matches ()'). The default is to do
filename completion.
Note that `rl_complete ()' has the identical calling conventions as
any other key-invokable function; this is because by default it is
bound to the `TAB' key.
* Variable: Function *rl_completion_entry_function
This is a pointer to the generator function for
`completion_matches ()'. If the value of
`rl_completion_entry_function' is `(Function *)NULL' then the
default filename generator function is used, namely
`filename_entry_function ()'.

File: readline.info, Node: Completion Functions, Next: Completion Variables, Prev: How Completing Works, Up: Custom Completers
Completion Functions
--------------------
Here is the complete list of callable completion functions present
in Readline.
* Function: rl_complete_internal (INT WHAT_TO_DO)
Complete the word at or before point. WHAT_TO_DO says what to do
with the completion. A value of `?' means list the possible
completions. `TAB' means do standard completion. `*' means
insert all of the possible completions.
* Function: rl_complete (INT IGNORE, INT INVOKING_KEY)
Complete the word at or before point. You have supplied the
function that does the initial simple matching selection
algorithm (see `completion_matches ()'). The default is to do
filename completion. This just calls `rl_complete_internal ()'
with an argument of `TAB'.
* Function: rl_possible_completions ()
List the possible completions. See description of `rl_complete
()'. This just calls `rl_complete_internal ()' with an argument
of `?'.
* Function: char **completion_matches (CHAR *TEXT, CHAR
*(*ENTRY_FUNCTION) ())
Returns an array of `(char *)' which is a list of completions for
TEXT. If there are no completions, returns `(char **)NULL'. The
first entry in the returned array is the substitution for TEXT.
The remaining entries are the possible completions. The array is
terminated with a `NULL' pointer.
ENTRY_FUNCTION is a function of two args, and returns a `(char
*)'. The first argument is TEXT. The second is a state
argument; it is zero on the first call, and non-zero on subsequent
calls. It returns a `NULL' pointer to the caller when there are
no more matches.
* Function: char *filename_completion_function (CHAR *TEXT, INT STATE)
A generator function for filename completion in the general case.
Note that completion in the Bash shell is a little different
because of all the pathnames that must be followed when looking
up the completion for a command.
* Function: char *username_completion_function (CHAR *TEXT, INT STATE)
A completion generator for usernames. TEXT contains a partial
username preceded by a random character (usually `~').

File: readline.info, Node: Completion Variables, Next: A Short Completion Example, Prev: Completion Functions, Up: Custom Completers
Completion Variables
--------------------
* Variable: Function *rl_completion_entry_function
A pointer to the generator function for `completion_matches ()'.
`NULL' means to use `filename_entry_function ()', the default
filename completer.
* Variable: Function *rl_attempted_completion_function
A pointer to an alternative function to create matches. The
function is called with TEXT, START, and END. START and END are
indices in `rl_line_buffer' saying what the boundaries of TEXT
are. If this function exists and returns `NULL' then
`rl_complete ()' will call the value of
`rl_completion_entry_function' to generate matches, otherwise the
array of strings returned will be used.
* Variable: int rl_completion_query_items
Up to this many items will be displayed in response to a
possible-completions call. After that, we ask the user if she is
sure she wants to see them all. The default value is 100.
* Variable: char *rl_basic_word_break_characters
The basic list of characters that signal a break between words
for the completer routine. The contents of this variable is what
breaks words in the Bash shell, i.e. " \t\n\"\\'`@$><=;|&{(".
* Variable: char *rl_completer_word_break_characters
The list of characters that signal a break between words for
`rl_complete_internal ()'. The default list is the contents of
`rl_basic_word_break_characters'.
* Variable: char *rl_special_prefixes
The list of characters that are word break characters, but should
be left in TEXT when it is passed to the completion function.
Programs can use this to help determine what kind of completing
to do.
* Variable: int rl_ignore_completion_duplicates
If non-zero, then disallow duplicates in the matches. Default is
1.
* Variable: int rl_filename_completion_desired
Non-zero means that the results of the matches are to be treated
as filenames. This is *always* zero on entry, and can only be
changed within a completion entry generator function.
* Variable: Function *rl_ignore_some_completions_function
This function, if defined, is called by the completer when real
filename completion is done, after all the matching names have
been generated. It is passed a `NULL' terminated array of `(char
*)' known as MATCHES in the code. The 1st element (`matches[0]')
is the maximal substring that is common to all matches. This
function can re-arrange the list of matches as required, but each
deleted element of the array must be `free()''d.

File: readline.info, Node: A Short Completion Example, Prev: Completion Variables, Up: Custom Completers
A Short Completion Example
--------------------------
Here is a small application demonstrating the use of the GNU
Readline library. It is called `fileman', and the source code resides
in `readline/examples/fileman.c'. This sample application provides
completion of command names, line editing features, and access to the
history list.
/* fileman.c -- A tiny application which demonstrates how to use the
GNU Readline library. This application interactively allows users
to manipulate files and their modes. */
#include <stdio.h>
#include <readline/readline.h>
#include <readline/history.h>
#include <sys/types.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/errno.h>
/* The names of functions that actually do the manipulation. */
int com_list (), com_view (), com_rename (), com_stat (), com_pwd ();
int com_delete (), com_help (), com_cd (), com_quit ();
/* A structure which contains information on the commands this program
can understand. */
typedef struct {
char *name; /* User printable name of the function. */
Function *func; /* Function to call to do the job. */
char *doc; /* Documentation for this function. */
} COMMAND;
COMMAND commands[] = {
{ "cd", com_cd, "Change to directory DIR" },
{ "delete", com_delete, "Delete FILE" },
{ "help", com_help, "Display this text" },
{ "?", com_help, "Synonym for `help'" },
{ "list", com_list, "List files in DIR" },
{ "ls", com_list, "Synonym for `list'" },
{ "pwd", com_pwd, "Print the current working directory" },
{ "quit", com_quit, "Quit using Fileman" },
{ "rename", com_rename, "Rename FILE to NEWNAME" },
{ "stat", com_stat, "Print out statistics on FILE" },
{ "view", com_view, "View the contents of FILE" },
{ (char *)NULL, (Function *)NULL, (char *)NULL }
};
/* The name of this program, as taken from argv[0]. */
char *progname;
/* When non-zero, this global means the user is done using this program. */
int done = 0;
main (argc, argv)
int argc;
char **argv;
{
progname = argv[0];
initialize_readline (); /* Bind our completer. */
/* Loop reading and executing lines until the user quits. */
while (!done)
{
char *line;
line = readline ("FileMan: ");
if (!line)
{
done = 1; /* Encountered EOF at top level. */
}
else
{
/* Remove leading and trailing whitespace from the line.
Then, if there is anything left, add it to the history list
and execute it. */
stripwhite (line);
if (*line)
{
add_history (line);
execute_line (line);
}
}
if (line)
free (line);
}
exit (0);
}
/* Execute a command line. */
execute_line (line)
char *line;
{
register int i;
COMMAND *find_command (), *command;
char *word;
/* Isolate the command word. */
i = 0;
while (line[i] && !whitespace (line[i]))
i++;
word = line;
if (line[i])
line[i++] = '\0';
command = find_command (word);
if (!command)
{
fprintf (stderr, "%s: No such command for FileMan.\n", word);
return;
}
/* Get argument to command, if any. */
while (whitespace (line[i]))
i++;
word = line + i;
/* Call the function. */
(*(command->func)) (word);
}
/* Look up NAME as the name of a command, and return a pointer to that
command. Return a NULL pointer if NAME isn't a command name. */
COMMAND *
find_command (name)
char *name;
{
register int i;
for (i = 0; commands[i].name; i++)
if (strcmp (name, commands[i].name) == 0)
return (&commands[i]);
return ((COMMAND *)NULL);
}
/* Strip whitespace from the start and end of STRING. */
stripwhite (string)
char *string;
{
register int i = 0;
while (whitespace (string[i]))
i++;
if (i)
strcpy (string, string + i);
i = strlen (string) - 1;
while (i > 0 && whitespace (string[i]))
i--;
string[++i] = '\0';
}
/* **************************************************************** */
/* */
/* Interface to Readline Completion */
/* */
/* **************************************************************** */
/* Tell the GNU Readline library how to complete. We want to try to complete
on command names if this is the first word in the line, or on filenames
if not. */
initialize_readline ()
{
char **fileman_completion ();
/* Allow conditional parsing of the ~/.inputrc file. */
rl_readline_name = "FileMan";
/* Tell the completer that we want a crack first. */
rl_attempted_completion_function = (Function *)fileman_completion;
}
/* Attempt to complete on the contents of TEXT. START and END show the
region of TEXT that contains the word to complete. We can use the
entire line in case we want to do some simple parsing. Return the
array of matches, or NULL if there aren't any. */
char **
fileman_completion (text, start, end)
char *text;
int start, end;
{
char **matches;
char *command_generator ();
matches = (char **)NULL;
/* If this word is at the start of the line, then it is a command
to complete. Otherwise it is the name of a file in the current
directory. */
if (start == 0)
matches = completion_matches (text, command_generator);
return (matches);
}
/* Generator function for command completion. STATE lets us know whether
to start from scratch; without any state (i.e. STATE == 0), then we
start at the top of the list. */
char *
command_generator (text, state)
char *text;
int state;
{
static int list_index, len;
char *name;
/* If this is a new word to complete, initialize now. This includes
saving the length of TEXT for efficiency, and initializing the index
variable to 0. */
if (!state)
{
list_index = 0;
len = strlen (text);
}
/* Return the next name which partially matches from the command list. */
while (name = commands[list_index].name)
{
list_index++;
if (strncmp (name, text, len) == 0)
return (name);
}
/* If no names matched, then return NULL. */
return ((char *)NULL);
}
/* **************************************************************** */
/* */
/* FileMan Commands */
/* */
/* **************************************************************** */
/* String to pass to system (). This is for the LIST, VIEW and RENAME
commands. */
static char syscom[1024];
/* List the file(s) named in arg. */
com_list (arg)
char *arg;
{
if (!arg)
arg = "*";
sprintf (syscom, "ls -FClg %s", arg);
system (syscom);
}
com_view (arg)
char *arg;
{
if (!valid_argument ("view", arg))
return;
sprintf (syscom, "cat %s | more", arg);
system (syscom);
}
com_rename (arg)
char *arg;
{
too_dangerous ("rename");
}
com_stat (arg)
char *arg;
{
struct stat finfo;
if (!valid_argument ("stat", arg))
return;
if (stat (arg, &finfo) == -1)
{
perror (arg);
return;
}
printf ("Statistics for `%s':\n", arg);
printf ("%s has %d link%s, and is %d bytes in length.\n", arg,
finfo.st_nlink, (finfo.st_nlink == 1) ? "" : "s", finfo.st_size);
printf (" Created on: %s", ctime (&finfo.st_ctime));
printf (" Last access at: %s", ctime (&finfo.st_atime));
printf ("Last modified at: %s", ctime (&finfo.st_mtime));
}
com_delete (arg)
char *arg;
{
too_dangerous ("delete");
}
/* Print out help for ARG, or for all of the commands if ARG is
not present. */
com_help (arg)
char *arg;
{
register int i;
int printed = 0;
for (i = 0; commands[i].name; i++)
{
if (!*arg || (strcmp (arg, commands[i].name) == 0))
{
printf ("%s\t\t%s.\n", commands[i].name, commands[i].doc);
printed++;
}
}
if (!printed)
{
printf ("No commands match `%s'. Possibilties are:\n", arg);
for (i = 0; commands[i].name; i++)
{
/* Print in six columns. */
if (printed == 6)
{
printed = 0;
printf ("\n");
}
printf ("%s\t", commands[i].name);
printed++;
}
if (printed)
printf ("\n");
}
}
/* Change to the directory ARG. */
com_cd (arg)
char *arg;
{
if (chdir (arg) == -1)
perror (arg);
com_pwd ("");
}
/* Print out the current working directory. */
com_pwd (ignore)
char *ignore;
{
char dir[1024];
(void) getwd (dir);
printf ("Current directory is %s\n", dir);
}
/* The user wishes to quit using this program. Just set DONE non-zero. */
com_quit (arg)
char *arg;
{
done = 1;
}
/* Function which tells you that you can't do this. */
too_dangerous (caller)
char *caller;
{
fprintf (stderr,
"%s: Too dangerous for me to distribute. Write it yourself.\n",
caller);
}
/* Return non-zero if ARG is a valid argument for CALLER, else print
an error message and return zero. */
int
valid_argument (caller, arg)
char *caller, *arg;
{
if (!arg || !*arg)
{
fprintf (stderr, "%s: Argument required.\n", caller);
return (0);
}
return (1);
}

File: readline.info, Node: Concept Index, Next: Function and Variable Index, Prev: Programming with GNU Readline, Up: Top
Concept Index
*************
* Menu:
* interaction, readline: Readline Interaction.
* readline, function: Default Behaviour.

File: readline.info, Node: Function and Variable Index, Prev: Concept Index, Up: Top
Function and Variable Index
***************************
* Menu:
* Function *rl_attempted_completion_function: Completion Variables.
* Function *rl_completion_entry_function: Completion Variables.
* Function *rl_completion_entry_function: How Completing Works.
* Function *rl_ignore_some_completions_function: Completion Variables.
* Keymap rl_copy_keymap: Keymaps.
* Keymap rl_make_bare_keymap: Keymaps.
* Keymap rl_make_keymap: Keymaps.
* abort (C-g): Miscellaneous Commands.
* accept-line (Newline, Return): Commands For History.
* backward-char (C-b): Commands For Moving.
* backward-delete-char (Rubout): Commands For Text.
* backward-kill-line (): Commands For Killing.
* backward-kill-word (M-DEL): Commands For Killing.
* backward-word (M-b): Commands For Moving.
* beginning-of-history (M-<): Commands For History.
* beginning-of-line (C-a): Commands For Moving.
* capitalize-word (M-c): Commands For Text.
* char **completion_matches: Completion Functions.
* char *filename_completion_function: Completion Functions.
* char *rl_basic_word_break_characters: Completion Variables.
* char *rl_completer_word_break_characters: Completion Variables.
* char *rl_line_buffer: Function Writing.
* char *rl_special_prefixes: Completion Variables.
* char *username_completion_function: Completion Functions.
* clear-screen (C-l): Commands For Moving.
* complete (TAB): Commands For Completion.
* delete-char (C-d): Commands For Text.
* digit-argument (M-0, M-1, ... M--): Numeric Arguments.
* do-uppercase-version (M-a, M-b, ...): Miscellaneous Commands.
* downcase-word (M-l): Commands For Text.
* editing-mode: Readline Init Syntax.
* end-of-history (M->): Commands For History.
* end-of-line (C-e): Commands For Moving.
* forward-char (C-f): Commands For Moving.
* forward-search-history (C-s): Commands For History.
* forward-word (M-f): Commands For Moving.
* horizontal-scroll-mode: Readline Init Syntax.
* int rl_bind_key: Binding Keys.
* int rl_bind_key_in_map: Binding Keys.
* int rl_completion_query_items: Completion Variables.
* int rl_end: Function Writing.
* int rl_filename_completion_desired: Completion Variables.
* int rl_ignore_completion_duplicates: Completion Variables.
* int rl_point: Function Writing.
* int rl_unbind_key: Binding Keys.
* int rl_unbind_key_in_map: Binding Keys.
* kill-line (C-k): Commands For Killing.
* kill-word (M-d): Commands For Killing.
* mark-modified-lines: Readline Init Syntax.
* next-history (C-n): Commands For History.
* possible-completions (M-?): Commands For Completion.
* prefer-visible-bell: Readline Init Syntax.
* prefix-meta (ESC): Miscellaneous Commands.
* previous-history (C-p): Commands For History.
* quoted-insert (C-q, C-v): Commands For Text.
* re-read-init-file (C-x C-r): Miscellaneous Commands.
* readline (): Default Behaviour.
* reverse-search-history (C-r): Commands For History.
* revert-line (M-r): Miscellaneous Commands.
* rl_add_defun: Function Naming.
* rl_begin_undo_group: Allowing Undoing.
* rl_bind_key (): Default Behaviour.
* rl_complete: How Completing Works.
* rl_complete: Completion Functions.
* rl_complete_internal: Completion Functions.
* rl_end_undo_group: Allowing Undoing.
* rl_generic_bind: Binding Keys.
* rl_modifying: Allowing Undoing.
* rl_possible_completions: Completion Functions.
* self-insert (a, b, A, 1, !, ...): Commands For Text.
* tab-insert (M-TAB): Commands For Text.
* transpose-chars (C-t): Commands For Text.
* transpose-words (M-t): Commands For Text.
* undo (C-_): Miscellaneous Commands.
* universal-argument (): Numeric Arguments.
* unix-line-discard (C-u): Commands For Killing.
* unix-word-rubout (C-w): Commands For Killing.
* upcase-word (M-u): Commands For Text.
* yank (C-y): Commands For Killing.
* yank-pop (M-y): Commands For Killing.

Tag Table:
Node: Top998
Node: Command Line Editing1611
Node: Introduction and Notation2034
Node: Readline Interaction3056
Node: Readline Bare Essentials4195
Node: Readline Movement Commands5703
Node: Readline Killing Commands6594
Node: Readline Arguments8438
Node: Readline Init File9390
Node: Readline Init Syntax10218
Node: Commands For Moving14208
Node: Commands For History14838
Node: Commands For Text15913
Node: Commands For Killing17581
Node: Numeric Arguments18708
Node: Commands For Completion19152
Node: Miscellaneous Commands19876
Node: Readline Vi Mode20718
Node: Programming with GNU Readline22328
Node: Default Behaviour23033
Node: Custom Functions26258
Node: The Function Type27057
Node: Function Naming27690
Node: Keymaps28942
Node: Binding Keys29857
Node: Function Writing31158
Node: Allowing Undoing32599
Node: Custom Completers36101
Node: How Completing Works36849
Node: Completion Functions39664
Node: Completion Variables42000
Node: A Short Completion Example44772
Node: Concept Index56398
Node: Function and Variable Index56687

End Tag Table
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