commit bash-20060209 snapshot

[thirdparty/bash.git] / lib / readline / doc / readline.info

This is readline.info, produced by makeinfo version 4.7 from
./rlman.texi.

   This manual describes the GNU Readline Library (version 5.2, 9
February 2006), a library which aids in the consistency of user
interface across discrete programs which provide a command line
interface.

   Copyright (C) 1988-2004 Free Software Foundation, Inc.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

     Permission is granted to copy, distribute and/or modify this
     document under the terms of the GNU Free Documentation License,
     Version 1.1 or any later version published by the Free Software
     Foundation; with no Invariant Sections, with the Front-Cover texts
     being "A GNU Manual," and with the Back-Cover Texts as in (a)
     below.  A copy of the license is included in the section entitled
     "GNU Free Documentation License."

     (a) The FSF's Back-Cover Text is: "You have freedom to copy and
     modify this GNU Manual, like GNU software.  Copies published by
     the Free Software Foundation raise funds for GNU development."

INFO-DIR-SECTION Libraries
START-INFO-DIR-ENTRY
* Readline: (readline).       The GNU readline library API.
END-INFO-DIR-ENTRY

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File: readline.info,  Node: Top,  Next: Command Line Editing,  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 which
provide a command line interface.

* Menu:

* Command Line Editing::           GNU Readline User's Manual.
* Programming with GNU Readline::  GNU Readline Programmer's Manual.
* Copying This Manual::            Copying this manual.
* Concept Index::                  Index of concepts described in this manual.
* Function and Variable Index::    Index of externally visible functions
                                   and variables.

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File: readline.info,  Node: Command Line Editing,  Next: Programming with GNU Readline,  Prev: Top,  Up: Top

1 Command Line Editing
**********************

This chapter describes the basic features of the GNU 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.
* Bindable Readline Commands::  A description of most of the Readline commands
                                available for binding
* Readline vi Mode::            A short description of how to make Readline
                                behave like the vi editor.

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File: readline.info,  Node: Introduction and Notation,  Next: Readline Interaction,  Up: Command Line Editing

1.1 Introduction to Line Editing
================================

The following paragraphs describe the notation used to represent
keystrokes.

   The text `C-k' is read as `Control-K' and describes the character
produced when the <k> key is pressed while the Control key is depressed.

   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 pressed.  The Meta key is labeled <ALT> on many keyboards.  On
keyboards with two keys labeled <ALT> (usually to either side of the
space bar), the <ALT> on the left side is generally set to work as a
Meta key.  The <ALT> 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.

   If you do not have a Meta or <ALT> key, or another key working as 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::).
If your keyboard lacks a <LFD> key, typing <C-j> will produce the
desired character.  The <RET> key may be labeled <Return> or <Enter> on
some keyboards.

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File: readline.info,  Node: Readline Interaction,  Next: Readline Init File,  Prev: Introduction and Notation,  Up: Command Line Editing

1.2 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 <RET>.  You do not have to be at the end of
the line to press <RET>; 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.
* Searching::                   Searching through previous lines.

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File: readline.info,  Node: Readline Bare Essentials,  Next: Readline Movement Commands,  Up: Readline Interaction

1.2.1 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 your erase
character to back up and delete the mistyped character.

   Sometimes you may mistype a character, and not notice the 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.  Afterwards, 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 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.

`C-b'
     Move back one character.

`C-f'
     Move forward one character.

<DEL> or <Backspace>
     Delete the character to the left of the cursor.

`C-d'
     Delete the character underneath the cursor.

Printing characters
     Insert the character into the line at the cursor.

`C-_' or `C-x C-u'
     Undo the last editing command.  You can undo all the way back to an
     empty line.

(Depending on your configuration, the <Backspace> key be set to delete
the character to the left of the cursor and the <DEL> key set to delete
the character underneath the cursor, like `C-d', rather than the
character to the left of the cursor.)

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File: readline.info,  Node: Readline Movement Commands,  Next: Readline Killing Commands,  Prev: Readline Bare Essentials,  Up: Readline Interaction

1.2.2 Readline Movement Commands
--------------------------------

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 `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, where a word is composed of letters and
     digits.

`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.

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File: readline.info,  Node: Readline Killing Commands,  Next: Readline Arguments,  Prev: Readline Movement Commands,  Up: Readline Interaction

1.2.3 Readline Killing Commands
-------------------------------

"Killing" text means to delete the text from the line, but to save it
away for later use, usually by "yanking" (re-inserting) it back into
the line.  (`Cut' and `paste' are more recent jargon for `kill' and
`yank'.)

   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.

   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 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.  

   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.  Word boundaries are the same
     as those used by `M-f'.

`M-<DEL>'
     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 `M-b'.

`C-w'
     Kill from the cursor to the previous whitespace.  This is
     different than `M-<DEL>' because the word boundaries differ.


   Here is how to "yank" the text back into the line.  Yanking means to
copy the most-recently-killed text from the kill buffer.

`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'.

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File: readline.info,  Node: Readline Arguments,  Next: Searching,  Prev: Readline Killing Commands,  Up: Readline Interaction

1.2.4 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' typed 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', which
will delete the next ten characters on the input line.

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File: readline.info,  Node: Searching,  Prev: Readline Arguments,  Up: Readline Interaction

1.2.5 Searching for Commands in the History
-------------------------------------------

Readline provides commands for searching through the command history
for lines containing a specified string.  There are two search modes:
"incremental" and "non-incremental".

   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 `C-r'.  Typing `C-s' searches
forward through the history.  The characters present in the value of
the `isearch-terminators' variable are used to terminate an incremental
search.  If that variable has not been assigned a value, the <ESC> and
`C-J' characters will terminate an incremental search.  `C-g' 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.

   To find other matching entries in the history list, type `C-r' or
`C-s' 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 <RET> 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.

   Readline remembers the last incremental search string.  If two
`C-r's are typed without any intervening characters defining a new
search string, any remembered search string is used.

   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.

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File: readline.info,  Node: Readline Init File,  Next: Bindable Readline Commands,  Prev: Readline Interaction,  Up: Command Line Editing

1.3 Readline Init File
======================

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 "inputrc" file, conventionally in his home
directory.  The name of this file is taken from the value of the
environment variable `INPUTRC'.  If that variable is unset, the default
is `~/.inputrc'.  If that file does not exist or cannot be read, the
ultimate default is `/etc/inputrc'.

   When a program which uses the Readline library starts up, the init
file is read, and the key bindings 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 File Syntax::   Syntax for the commands in the inputrc file.

* Conditional Init Constructs:: Conditional key bindings in the inputrc file.

* Sample Init File::            An example inputrc file.

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File: readline.info,  Node: Readline Init File Syntax,  Next: Conditional Init Constructs,  Up: Readline Init File

1.3.1 Readline Init File Syntax
-------------------------------

There are only a few basic constructs allowed in the Readline init
file.  Blank lines are ignored.  Lines beginning with a `#' are
comments.  Lines beginning with a `$' indicate conditional constructs
(*note Conditional Init Constructs::).  Other lines denote variable
settings and key bindings.

Variable Settings
     You can modify the run-time behavior of Readline by altering the
     values of variables in Readline using the `set' command within the
     init file.  The syntax is simple:

          set VARIABLE VALUE

     Here, for example, is how to change from the default Emacs-like
     key binding to use `vi' line editing commands:

          set editing-mode vi

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

     Boolean variables (those that can be set to on or off) are set to
     on if the value is null or empty, ON (case-insensitive), or 1.
     Any other value results in the variable being set to off.

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

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

    `bind-tty-special-chars'
          If set to `on', Readline attempts to bind the control
          characters treated specially by the kernel's terminal driver
          to their Readline equivalents.

    `comment-begin'
          The string to insert at the beginning of the line when the
          `insert-comment' command is executed.  The default value is
          `"#"'.

    `completion-ignore-case'
          If set to `on', Readline performs filename matching and
          completion in a case-insensitive fashion.  The default value
          is `off'.

    `completion-query-items'
          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 `100'.

    `convert-meta'
          If set to `on', Readline will convert characters with the
          eighth bit set to an ASCII key sequence by stripping the
          eighth bit and prefixing an <ESC> character, converting them
          to a meta-prefixed key sequence.  The default value is `on'.

    `disable-completion'
          If set to `On', Readline will inhibit word completion.
          Completion  characters will be inserted into the line as if
          they had been mapped to `self-insert'.  The default is `off'.

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

    `enable-keypad'
          When set to `on', Readline will try to enable the application
          keypad when it is called.  Some systems need this to enable
          the arrow keys.  The default is `off'.

    `expand-tilde'
          If set to `on', tilde expansion is performed when Readline
          attempts word completion.  The default is `off'.

    `history-preserve-point'
          If set to `on', the history code attempts to place point at
          the same location on each history line retrieved with
          `previous-history' or `next-history'.  The default is `off'.

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

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

    `isearch-terminators'
          The string of characters that should terminate an incremental
          search without subsequently executing the character as a
          command (*note Searching::).  If this variable has not been
          given a value, the characters <ESC> and `C-J' will terminate
          an incremental search.

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

    `mark-directories'
          If set to `on', completed directory names have a slash
          appended.  The default is `on'.

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

    `mark-symlinked-directories'
          If set to `on', completed names which are symbolic links to
          directories have a slash appended (subject to the value of
          `mark-directories').  The default is `off'.

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

    `output-meta'
          If set to `on', Readline will display characters with the
          eighth bit set directly rather than as a meta-prefixed escape
          sequence.  The default is `off'.

    `page-completions'
          If set to `on', Readline uses an internal `more'-like pager
          to display a screenful of possible completions at a time.
          This variable is `on' by default.

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

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

    `show-all-if-unmodified'
          This alters the default behavior of the completion functions
          in a fashion similar to SHOW-ALL-IF-AMBIGUOUS.  If set to
          `on', 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 `off'.

    `visible-stats'
          If set to `on', a character denoting a file's type is
          appended to the filename when listing possible completions.
          The default is `off'.


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

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

     In addition to command names, readline allows keys to be bound to
     a string that is inserted when the key is pressed (a MACRO).

    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', `M-DEL' is bound to the function
          `backward-kill-word', 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).

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

    "KEYSEQ": FUNCTION-NAME or MACRO
          KEYSEQ differs from KEYNAME 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.

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

          In the above example, `C-u' is again 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'.


     The following GNU Emacs style escape sequences are available when
     specifying key sequences:

    `\C-'
          control prefix

    `\M-'
          meta prefix

    `\e'
          an escape character

    `\\'
          backslash

    `\"'
          <">, a double quotation mark

    `\''
          <'>, a single quote or apostrophe

     In addition to the GNU Emacs style escape sequences, a second set
     of backslash escapes is available:

    `\a'
          alert (bell)

    `\b'
          backspace

    `\d'
          delete

    `\f'
          form feed

    `\n'
          newline

    `\r'
          carriage return

    `\t'
          horizontal tab

    `\v'
          vertical tab

    `\NNN'
          the eight-bit character whose value is the octal value NNN
          (one to three digits)

    `\xHH'
          the eight-bit character whose value is the hexadecimal value
          HH (one or two hex digits)

     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 `"' and `''.  For example,
     the following binding will make `C-x \' insert a single `\' into
     the line:
          "\C-x\\": "\\"


\1f
File: readline.info,  Node: Conditional Init Constructs,  Next: Sample Init File,  Prev: Readline Init File Syntax,  Up: Readline Init File

1.3.2 Conditional Init Constructs
---------------------------------

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

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

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

    `term'
          The `term=' 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
          `=' is tested against both the full name of the terminal and
          the portion of the terminal name before the first `-'.  This
          allows `sun' to match both `sun' and `sun-cmd', for instance.

    `application'
          The APPLICATION construct is used to include
          application-specific settings.  Each program using the
          Readline library sets the APPLICATION NAME, 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:
               $if Bash
               # Quote the current or previous word
               "\C-xq": "\eb\"\ef\""
               $endif

`$endif'
     This command, as seen in the previous example, terminates an `$if'
     command.

`$else'
     Commands in this branch of the `$if' directive are executed if the
     test fails.

`$include'
     This directive takes a single filename as an argument and reads
     commands and bindings from that file.  For example, the following
     directive reads from `/etc/inputrc':
          $include /etc/inputrc

\1f
File: readline.info,  Node: Sample Init File,  Prev: Conditional Init Constructs,  Up: Readline Init File

1.3.3 Sample Init File
----------------------

Here is an example of an INPUTRC file.  This illustrates key binding,
variable assignment, and conditional syntax.


     # 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

\1f
File: readline.info,  Node: Bindable Readline Commands,  Next: Readline vi Mode,  Prev: Readline Init File,  Up: Command Line Editing

1.4 Bindable Readline Commands
==============================

* 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.
* Keyboard Macros::             Saving and re-executing typed characters
* Miscellaneous Commands::      Other miscellaneous commands.

   This section describes Readline commands that may be bound to key
sequences.  Command names without an accompanying key sequence are
unbound by default.

   In the following descriptions, "point" refers to the current cursor
position, and "mark" refers to a cursor position saved by the
`set-mark' command.  The text between the point and mark is referred to
as the "region".

\1f
File: readline.info,  Node: Commands For Moving,  Next: Commands For History,  Up: Bindable Readline Commands

1.4.1 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.  Words are composed of
     letters and digits.

`backward-word (M-b)'
     Move back to the start of the current or previous word.  Words are
     composed of letters and digits.

`clear-screen (C-l)'
     Clear the screen and redraw the current line, leaving the current
     line at the top of the screen.

`redraw-current-line ()'
     Refresh the current line.  By default, this is unbound.


\1f
File: readline.info,  Node: Commands For History,  Next: Commands For Text,  Prev: Commands For Moving,  Up: Bindable Readline Commands

1.4.2 Commands For Manipulating The History
-------------------------------------------

`accept-line (Newline or Return)'
     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 `add_history()'.  If this line is a modified history line,
     the history line is restored to its original state.

`previous-history (C-p)'
     Move `back' through the history list, fetching the previous
     command.

`next-history (C-n)'
     Move `forward' through the history list, fetching the next command.

`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 currently
     being entered.

`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 necessary.  This is an incremental
     search.

`non-incremental-reverse-search-history (M-p)'
     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.

`non-incremental-forward-search-history (M-n)'
     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.

`history-search-forward ()'
     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.

`history-search-backward ()'
     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.

`yank-nth-arg (M-C-y)'
     Insert the first argument to the previous command (usually the
     second word on the previous line) at point.  With an argument N,
     insert the Nth word from the previous command (the words in the
     previous command begin with word 0).  A negative argument inserts
     the Nth word from the end of the previous command.  Once the
     argument N is computed, the argument is extracted as if the `!N'
     history expansion had been specified.

`yank-last-arg (M-. or M-_)'
     Insert last argument to the previous command (the last word of the
     previous history entry).  With an argument, behave exactly like
     `yank-nth-arg'.  Successive calls to `yank-last-arg' 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 `!$' history expansion had been specified.


\1f
File: readline.info,  Node: Commands For Text,  Next: Commands For Killing,  Prev: Commands For History,  Up: Bindable Readline Commands

1.4.3 Commands For Changing Text
--------------------------------

`delete-char (C-d)'
     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 `delete-char', then return EOF.

`backward-delete-char (Rubout)'
     Delete the character behind the cursor.  A numeric argument means
     to kill the characters instead of deleting them.

`forward-backward-delete-char ()'
     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.

`quoted-insert (C-q or C-v)'
     Add the next character typed to the line verbatim.  This is how to
     insert key sequences 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 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.

`transpose-words (M-t)'
     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.

`upcase-word (M-u)'
     Uppercase the current (or following) word.  With a negative
     argument, uppercase the previous word, but do not move the cursor.

`downcase-word (M-l)'
     Lowercase the current (or following) word.  With a negative
     argument, lowercase the previous word, but do not move the cursor.

`capitalize-word (M-c)'
     Capitalize the current (or following) word.  With a negative
     argument, capitalize the previous word, but do not move the cursor.

`overwrite-mode ()'
     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
     `emacs' mode; `vi' mode does overwrite differently.  Each call to
     `readline()' starts in insert mode.

     In overwrite mode, characters bound to `self-insert' replace the
     text at point rather than pushing the text to the right.
     Characters bound to `backward-delete-char' replace the character
     before point with a space.

     By default, this command is unbound.


\1f
File: readline.info,  Node: Commands For Killing,  Next: Numeric Arguments,  Prev: Commands For Text,  Up: Bindable Readline Commands

1.4.4 Killing And Yanking
-------------------------

`kill-line (C-k)'
     Kill the text from point to the end of the line.

`backward-kill-line (C-x Rubout)'
     Kill backward to the beginning of the line.

`unix-line-discard (C-u)'
     Kill backward from the cursor to the beginning of the current line.

`kill-whole-line ()'
     Kill all characters on the current line, no matter where point is.
     By default, this is unbound.

`kill-word (M-d)'
     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 `forward-word'.

`backward-kill-word (M-<DEL>)'
     Kill the word behind point.  Word boundaries are the same as
     `backward-word'.

`unix-word-rubout (C-w)'
     Kill the word behind point, using white space as a word boundary.
     The killed text is saved on the kill-ring.

`unix-filename-rubout ()'
     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.

`delete-horizontal-space ()'
     Delete all spaces and tabs around point.  By default, this is
     unbound.

`kill-region ()'
     Kill the text in the current region.  By default, this command is
     unbound.

`copy-region-as-kill ()'
     Copy the text in the region to the kill buffer, so it can be yanked
     right away.  By default, this command is unbound.

`copy-backward-word ()'
     Copy the word before point to the kill buffer.  The word
     boundaries are the same as `backward-word'.  By default, this
     command is unbound.

`copy-forward-word ()'
     Copy the word following point to the kill buffer.  The word
     boundaries are the same as `forward-word'.  By default, this
     command is unbound.

`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'.

\1f
File: readline.info,  Node: Numeric Arguments,  Next: Commands For Completion,  Prev: Commands For Killing,  Up: Bindable Readline Commands

1.4.5 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 ()'
     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 `universal-argument' 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.

\1f
File: readline.info,  Node: Commands For Completion,  Next: Keyboard Macros,  Prev: Numeric Arguments,  Up: Bindable Readline Commands

1.4.6 Letting Readline Type For You
-----------------------------------

`complete (<TAB>)'
     Attempt to perform completion on the text before point.  The
     actual completion performed is application-specific.  The default
     is filename completion.

`possible-completions (M-?)'
     List the possible completions of the text before point.

`insert-completions (M-*)'
     Insert all completions of the text before point that would have
     been generated by `possible-completions'.

`menu-complete ()'
     Similar to `complete', but replaces the word to be completed with
     a single match from the list of possible completions.  Repeated
     execution of `menu-complete' 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
     `bell-style') and the original text is restored.  An argument of N
     moves N 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 <TAB>, but is unbound by
     default.

`delete-char-or-list ()'
     Deletes the character under the cursor if not at the beginning or
     end of the line (like `delete-char').  If at the end of the line,
     behaves identically to `possible-completions'.  This command is
     unbound by default.


\1f
File: readline.info,  Node: Keyboard Macros,  Next: Miscellaneous Commands,  Prev: Commands For Completion,  Up: Bindable Readline Commands

1.4.7 Keyboard Macros
---------------------

`start-kbd-macro (C-x ()'
     Begin saving the characters typed into the current keyboard macro.

`end-kbd-macro (C-x ))'
     Stop saving the characters typed into the current keyboard macro
     and save the definition.

`call-last-kbd-macro (C-x e)'
     Re-execute the last keyboard macro defined, by making the
     characters in the macro appear as if typed at the keyboard.


\1f
File: readline.info,  Node: Miscellaneous Commands,  Prev: Keyboard Macros,  Up: Bindable Readline Commands

1.4.8 Some Miscellaneous Commands
---------------------------------

`re-read-init-file (C-x C-r)'
     Read in the contents of the INPUTRC file, and incorporate any
     bindings or variable assignments found there.

`abort (C-g)'
     Abort the current editing command and ring the terminal's bell
     (subject to the setting of `bell-style').

`do-uppercase-version (M-a, M-b, M-X, ...)'
     If the metafied character X is lowercase, run the command that is
     bound to the corresponding uppercase character.

`prefix-meta (<ESC>)'
     Metafy the next character typed.  This is for keyboards without a
     meta key.  Typing `<ESC> f' is equivalent to typing `M-f'.

`undo (C-_ or C-x C-u)'
     Incremental undo, separately remembered for each line.

`revert-line (M-r)'
     Undo all changes made to this line.  This is like executing the
     `undo' command enough times to get back to the beginning.

`tilde-expand (M-~)'
     Perform tilde expansion on the current word.

`set-mark (C-@)'
     Set the mark to the point.  If a numeric argument is supplied, the
     mark is set to that position.

`exchange-point-and-mark (C-x C-x)'
     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.

`character-search (C-])'
     A character is read and point is moved to the next occurrence of
     that character.  A negative count searches for previous
     occurrences.

`character-search-backward (M-C-])'
     A character is read and point is moved to the previous occurrence
     of that character.  A negative count searches for subsequent
     occurrences.

`insert-comment (M-#)'
     Without a numeric argument, the value of the `comment-begin'
     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 `comment-begin', the value is inserted, otherwise the
     characters in `comment-begin' are deleted from the beginning of
     the line.  In either case, the line is accepted as if a newline
     had been typed.

`dump-functions ()'
     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 INPUTRC
     file.  This command is unbound by default.

`dump-variables ()'
     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
     INPUTRC file.  This command is unbound by default.

`dump-macros ()'
     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
     INPUTRC file.  This command is unbound by default.

`emacs-editing-mode (C-e)'
     When in `vi' command mode, this causes a switch to `emacs' editing
     mode.

`vi-editing-mode (M-C-j)'
     When in `emacs' editing mode, this causes a switch to `vi' editing
     mode.


\1f
File: readline.info,  Node: Readline vi Mode,  Prev: Bindable Readline Commands,  Up: Command Line Editing

1.5 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.
The Readline `vi' mode behaves as specified in the POSIX 1003.2
standard.

   In order to switch interactively between `emacs' and `vi' editing
modes, use the command `M-C-j' (bound to emacs-editing-mode when in
`vi' mode and to vi-editing-mode in `emacs' mode).  The Readline
default is `emacs' 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 `command' mode, where you can edit the text of the line with
the standard `vi' movement keys, move to previous history lines with
`k' and subsequent lines with `j', and so forth.

   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.

   Copyright (C) 1988-2005 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.

\1f
File: readline.info,  Node: Programming with GNU Readline,  Next: Copying This Manual,  Prev: Command Line Editing,  Up: Top

2 Programming with GNU Readline
*******************************

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.

* Menu:

* Basic Behavior::      Using the default behavior of Readline.
* Custom Functions::    Adding your own functions to Readline.
* Readline Variables::                  Variables accessible to custom
                                        functions.
* Readline Convenience Functions::      Functions which Readline supplies to
                                        aid in writing your own custom
                                        functions.
* Readline Signal Handling::    How Readline behaves when it receives signals.
* Custom Completers::   Supplanting or supplementing Readline's
                        completion functions.

\1f
File: readline.info,  Node: Basic Behavior,  Next: Custom Functions,  Up: Programming with GNU Readline

2.1 Basic Behavior
==================

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()' or
`fgets()'.

   The function `readline()' prints a prompt PROMPT and then reads and
returns a single line of text from the user.  If PROMPT is `NULL' or
the empty string, no prompt is displayed.  The line `readline' returns
is allocated with `malloc()'; the caller should `free()' the line when
it has finished with it.  The declaration for `readline' in ANSI C is

     `char *readline (const 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 returned
has the final newline removed, so only the text 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 had been 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 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 `gets()' library
function, and has the advantage of no static buffer to overflow:

     /* 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 && *line_read)
         add_history (line_read);

       return (line_read);
     }

   This function 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, rl_command_func_t *FUNCTION);'

   `rl_bind_key()' takes two arguments: KEY is the character that you
want to bind, and FUNCTION is the address of the function to call when
KEY is pressed.  Binding <TAB> to `rl_insert()' makes <TAB> insert
itself.  `rl_bind_key()' returns non-zero if KEY is not a valid ASCII
character code (between 0 and 255).

   Thus, to disable the default <TAB> behavior, the following suffices:
     `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 (*note Custom Completers::).

\1f
File: readline.info,  Node: Custom Functions,  Next: Readline Variables,  Prev: Basic Behavior,  Up: Programming with GNU Readline

2.2 Custom Functions
====================

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.

   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 `<readline/readline.h>' in any file that
uses Readline's features.  Since some of the definitions in
`readline.h' use the `stdio' library, the file `<stdio.h>' should be
included before `readline.h'.

   `readline.h' defines a C preprocessor variable that should be
treated as an integer, `RL_READLINE_VERSION', 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 0xMMMM.  MM is the
two-digit major version number; MM is the two-digit minor version
number.  For Readline 4.2, for example, the value of
`RL_READLINE_VERSION' would be `0x0402'.

* Menu:

* Readline Typedefs::   C declarations to make code readable.
* Function Writing::    Variables and calling conventions.

\1f
File: readline.info,  Node: Readline Typedefs,  Next: Function Writing,  Up: Custom Functions

2.2.1 Readline Typedefs
-----------------------

For readabilty, we declare a number of new object types, all pointers
to functions.

   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.

   For instance, say we want to declare a variable FUNC as a pointer to
a function which takes two `int' arguments and returns an `int' (this
is the type of all of the Readline bindable functions).  Instead of the
classic C declaration

   `int (*func)();'

or the ANSI-C style declaration

   `int (*func)(int, int);'

we may write

   `rl_command_func_t *func;'

   The full list of function pointer types available is

`typedef int rl_command_func_t (int, int);'

`typedef char *rl_compentry_func_t (const char *, int);'

`typedef char **rl_completion_func_t (const char *, int, int);'

`typedef char *rl_quote_func_t (char *, int, char *);'

`typedef char *rl_dequote_func_t (char *, int);'

`typedef int rl_compignore_func_t (char **);'

`typedef void rl_compdisp_func_t (char **, int, int);'

`typedef int rl_hook_func_t (void);'

`typedef int rl_getc_func_t (FILE *);'

`typedef int rl_linebuf_func_t (char *, int);'

`typedef int rl_intfunc_t (int);'

`#define rl_ivoidfunc_t rl_hook_func_t'

`typedef int rl_icpfunc_t (char *);'

`typedef int rl_icppfunc_t (char **);'

`typedef void rl_voidfunc_t (void);'

`typedef void rl_vintfunc_t (int);'

`typedef void rl_vcpfunc_t (char *);'

`typedef void rl_vcppfunc_t (char **);'

\1f
File: readline.info,  Node: Function Writing,  Prev: Readline Typedefs,  Up: Custom Functions

2.2.2 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 read so far.

   The calling sequence for a command `foo' looks like

     `int 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, 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.

   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.

\1f
File: readline.info,  Node: Readline Variables,  Next: Readline Convenience Functions,  Prev: Custom Functions,  Up: Programming with GNU Readline

2.3 Readline Variables
======================

These variables are available to function writers.

 -- Variable: char * rl_line_buffer
     This is the line gathered so far.  You are welcome to modify the
     contents of the line, but see *Note Allowing Undoing::.  The
     function `rl_extend_line_buffer' is available to increase the
     memory allocated to `rl_line_buffer'.

 -- Variable: int rl_point
     The offset of the current cursor position in `rl_line_buffer' (the
     _point_).

 -- Variable: int rl_end
     The number of characters present in `rl_line_buffer'.  When
     `rl_point' is at the end of the line, `rl_point' and `rl_end' are
     equal.

 -- Variable: int rl_mark
     The MARK (saved position) in the current line.  If set, the mark
     and point define a _region_.

 -- Variable: int rl_done
     Setting this to a non-zero value causes Readline to return the
     current line immediately.

 -- Variable: int rl_num_chars_to_read
     Setting this to a positive value before calling `readline()' causes
     Readline to return after accepting that many characters, rather
     than reading up to a character bound to `accept-line'.

 -- Variable: int rl_pending_input
     Setting this to a value makes it the next keystroke read.  This is
     a way to stuff a single character into the input stream.

 -- Variable: int rl_dispatching
     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.

 -- Variable: int rl_erase_empty_line
     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.

 -- Variable: char * rl_prompt
     The prompt Readline uses.  This is set from the argument to
     `readline()', and should not be assigned to directly.  The
     `rl_set_prompt()' function (*note Redisplay::) may be used to
     modify the prompt string after calling `readline()'.

 -- Variable: int rl_already_prompted
     If an application wishes to display the prompt itself, rather than
     have Readline do it the first time `readline()' is called, it
     should set this variable to a non-zero value after displaying the
     prompt.  The prompt must also be passed as the argument to
     `readline()' so the redisplay functions can update the display
     properly.  The calling application is responsible for managing the
     value; Readline never sets it.

 -- Variable: const char * rl_library_version
     The version number of this revision of the library.

 -- Variable: int rl_readline_version
     An integer encoding the current version of the library.  The
     encoding is of the form 0xMMMM, where MM is the two-digit major
     version number, and MM is the two-digit minor version number.  For
     example, for Readline-4.2, `rl_readline_version' would have the
     value 0x0402.

 -- Variable: int rl_gnu_readline_p
     Always set to 1, denoting that this is GNU readline rather than
     some emulation.

 -- Variable: const char * rl_terminal_name
     The terminal type, used for initialization.  If not set by the
     application, Readline sets this to the value of the `TERM'
     environment variable the first time it is called.

 -- Variable: const char * rl_readline_name
     This variable is set to a unique name by each application using
     Readline.  The value allows conditional parsing of the inputrc file
     (*note Conditional Init Constructs::).

 -- Variable: FILE * rl_instream
     The stdio stream from which Readline reads input.  If `NULL',
     Readline defaults to STDIN.

 -- Variable: FILE * rl_outstream
     The stdio stream to which Readline performs output.  If `NULL',
     Readline defaults to STDOUT.

 -- Variable: int rl_prefer_env_winsize
     If non-zero, Readline gives values found in the `LINES' and
     `COLUMNS' environment variables greater precedence than values
     fetched from the kernel when computing the screen dimensions.

 -- Variable: rl_command_func_t * rl_last_func
     The address of the last command function Readline executed.  May
     be used to test whether or not a function is being executed twice
     in succession, for example.

 -- Variable: rl_hook_func_t * rl_startup_hook
     If non-zero, this is the address of a function to call just before
     `readline' prints the first prompt.

 -- Variable: rl_hook_func_t * rl_pre_input_hook
     If non-zero, this is the address of a function to call after the
     first prompt has been printed and just before `readline' starts
     reading input characters.

 -- Variable: rl_hook_func_t * rl_event_hook
     If non-zero, this is the address of a function to call periodically
     when Readline is waiting for terminal input.  By default, this
     will be called at most ten times a second if there is no keyboard
     input.

 -- Variable: rl_getc_func_t * rl_getc_function
     If non-zero, Readline will call indirectly through this pointer to
     get a character from the input stream.  By default, it is set to
     `rl_getc', the default Readline character input function (*note
     Character Input::).

 -- Variable: rl_voidfunc_t * rl_redisplay_function
     If non-zero, Readline will call indirectly through this pointer to
     update the display with the current contents of the editing buffer.
     By default, it is set to `rl_redisplay', the default Readline
     redisplay function (*note Redisplay::).

 -- Variable: rl_vintfunc_t * rl_prep_term_function
     If non-zero, Readline will call indirectly through this pointer to
     initialize the terminal.  The function takes a single argument, an
     `int' flag that says whether or not to use eight-bit characters.
     By default, this is set to `rl_prep_terminal' (*note Terminal
     Management::).

 -- Variable: rl_voidfunc_t * rl_deprep_term_function
     If non-zero, Readline will call indirectly through this pointer to
     reset the terminal.  This function should undo the effects of
     `rl_prep_term_function'.  By default, this is set to
     `rl_deprep_terminal' (*note Terminal Management::).

 -- Variable: Keymap rl_executing_keymap
     This variable is set to the keymap (*note Keymaps::) in which the
     currently executing readline function was found.

 -- Variable: Keymap rl_binding_keymap
     This variable is set to the keymap (*note Keymaps::) in which the
     last key binding occurred.

 -- Variable: char * rl_executing_macro
     This variable is set to the text of any currently-executing macro.

 -- Variable: int rl_readline_state
     A variable with bit values that encapsulate the current Readline
     state.  A bit is set with the `RL_SETSTATE' macro, and unset with
     the `RL_UNSETSTATE' macro.  Use the `RL_ISSTATE' macro to test
     whether a particular state bit is set.  Current state bits include:

    `RL_STATE_NONE'
          Readline has not yet been called, nor has it begun to
          intialize.

    `RL_STATE_INITIALIZING'
          Readline is initializing its internal data structures.

    `RL_STATE_INITIALIZED'
          Readline has completed its initialization.

    `RL_STATE_TERMPREPPED'
          Readline has modified the terminal modes to do its own input
          and redisplay.

    `RL_STATE_READCMD'
          Readline is reading a command from the keyboard.

    `RL_STATE_METANEXT'
          Readline is reading more input after reading the meta-prefix
          character.

    `RL_STATE_DISPATCHING'
          Readline is dispatching to a command.

    `RL_STATE_MOREINPUT'
          Readline is reading more input while executing an editing
          command.

    `RL_STATE_ISEARCH'
          Readline is performing an incremental history search.

    `RL_STATE_NSEARCH'
          Readline is performing a non-incremental history search.

    `RL_STATE_SEARCH'
          Readline is searching backward or forward through the history
          for a string.

    `RL_STATE_NUMERICARG'
          Readline is reading a numeric argument.

    `RL_STATE_MACROINPUT'
          Readline is currently getting its input from a
          previously-defined keyboard macro.

    `RL_STATE_MACRODEF'
          Readline is currently reading characters defining a keyboard
          macro.

    `RL_STATE_OVERWRITE'
          Readline is in overwrite mode.

    `RL_STATE_COMPLETING'
          Readline is performing word completion.

    `RL_STATE_SIGHANDLER'
          Readline is currently executing the readline signal handler.

    `RL_STATE_UNDOING'
          Readline is performing an undo.

    `RL_STATE_DONE'
          Readline has read a key sequence bound to `accept-line' and
          is about to return the line to the caller.


 -- Variable: int rl_explicit_arg
     Set to a non-zero value if an explicit numeric argument was
     specified by the user.  Only valid in a bindable command function.

 -- Variable: int rl_numeric_arg
     Set to the value of any numeric argument explicitly specified by
     the user before executing the current Readline function.  Only
     valid in a bindable command function.

 -- Variable: int rl_editing_mode
     Set to a value denoting Readline's current editing mode.  A value
     of 1 means Readline is currently in emacs mode; 0 means that vi
     mode is active.

\1f
File: readline.info,  Node: Readline Convenience Functions,  Next: Readline Signal Handling,  Prev: Readline Variables,  Up: Programming with GNU Readline

2.4 Readline Convenience Functions
==================================

* Menu:

* Function Naming::     How to give a function you write a name.
* Keymaps::             Making keymaps.
* Binding Keys::        Changing Keymaps.
* Associating Function Names and Bindings::     Translate function names to
                                                key sequences.
* Allowing Undoing::    How to make your functions undoable.
* Redisplay::           Functions to control line display.
* Modifying Text::      Functions to modify `rl_line_buffer'.
* Character Input::     Functions to read keyboard input.
* Terminal Management:: Functions to manage terminal settings.
* Utility Functions::   Generally useful functions and hooks.
* Miscellaneous Functions::     Functions that don't fall into any category.
* Alternate Interface:: Using Readline in a `callback' fashion.
* A Readline Example::          An example Readline function.

\1f
File: readline.info,  Node: Function Naming,  Next: Keymaps,  Up: Readline Convenience Functions

2.4.1 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: int rl_add_defun (const char *name, rl_command_func_t
          *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.  If you need to do something other than
adding a function to Readline, you may need to use the underlying
functions described below.

\1f
File: readline.info,  Node: Keymaps,  Next: Binding Keys,  Prev: Function Naming,  Up: Readline Convenience Functions

2.4.2 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 (void)
     Returns a new, empty keymap.  The space for the keymap is
     allocated with `malloc()'; the caller should free it by calling
     `rl_discard_keymap()' when done.

 -- Function: Keymap rl_copy_keymap (Keymap map)
     Return a new keymap which is a copy of MAP.

 -- Function: Keymap rl_make_keymap (void)
     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.

 -- Function: void rl_discard_keymap (Keymap keymap)
     Free the storage associated with KEYMAP.

   Readline has several internal keymaps.  These functions allow you to
change which keymap is active.

 -- Function: Keymap rl_get_keymap (void)
     Returns the currently active keymap.

 -- Function: void rl_set_keymap (Keymap keymap)
     Makes KEYMAP the currently active keymap.

 -- Function: Keymap rl_get_keymap_by_name (const char *name)
     Return the keymap matching NAME.  NAME is one which would be
     supplied in a `set keymap' inputrc line (*note Readline Init
     File::).

 -- Function: char * rl_get_keymap_name (Keymap keymap)
     Return the name matching KEYMAP.  NAME is one which would be
     supplied in a `set keymap' inputrc line (*note Readline Init
     File::).

\1f
File: readline.info,  Node: Binding Keys,  Next: Associating Function Names and Bindings,  Prev: Keymaps,  Up: Readline Convenience Functions

2.4.3 Binding Keys
------------------

Key sequences are associate with functions through the keymap.
Readline has several internal keymaps: `emacs_standard_keymap',
`emacs_meta_keymap', `emacs_ctlx_keymap', `vi_movement_keymap', and
`vi_insertion_keymap'.  `emacs_standard_keymap' is the default, and the
examples in this manual assume that.

   Since `readline()' installs a set of default key bindings the first
time it is called, there is always the danger that a custom binding
installed before the first call to `readline()' will be overridden.  An
alternate mechanism is to install custom key bindings in an
initialization function assigned to the `rl_startup_hook' variable
(*note Readline Variables::).

   These functions manage key bindings.

 -- Function: int rl_bind_key (int key, rl_command_func_t *function)
     Binds KEY to FUNCTION in the currently active keymap.  Returns
     non-zero in the case of an invalid KEY.

 -- Function: int rl_bind_key_in_map (int key, rl_command_func_t
          *function, Keymap map)
     Bind KEY to FUNCTION in MAP.  Returns non-zero in the case of an
     invalid KEY.

 -- Function: int rl_bind_key_if_unbound (int key, rl_command_func_t
          *function)
     Binds KEY to FUNCTION if it is not already bound in the currently
     active keymap.  Returns non-zero in the case of an invalid KEY or
     if KEY is already bound.

 -- Function: int rl_bind_key_if_unbound_in_map (int key,
          rl_command_func_t *function, Keymap map)
     Binds KEY to FUNCTION if it is not already bound in MAP.  Returns
     non-zero in the case of an invalid KEY or if KEY is already bound.

 -- Function: int rl_unbind_key (int key)
     Bind KEY to the null function in the currently active keymap.
     Returns non-zero in case of error.

 -- Function: int rl_unbind_key_in_map (int key, Keymap map)
     Bind KEY to the null function in MAP.  Returns non-zero in case of
     error.

 -- Function: int rl_unbind_function_in_map (rl_command_func_t
          *function, Keymap map)
     Unbind all keys that execute FUNCTION in MAP.

 -- Function: int rl_unbind_command_in_map (const char *command, Keymap
          map)
     Unbind all keys that are bound to COMMAND in MAP.

 -- Function: int rl_bind_keyseq (const char *keyseq, rl_command_func_t
          *function)
     Bind the key sequence represented by the string KEYSEQ to the
     function FUNCTION, beginning in the current keymap.  This makes
     new keymaps as necessary.  The return value is non-zero if KEYSEQ
     is invalid.

 -- Function: int rl_bind_keyseq_in_map (const char *keyseq,
          rl_command_func_t *function, Keymap map)
     Bind the key sequence represented by the string KEYSEQ to the
     function FUNCTION.  This makes new keymaps as necessary.  Initial
     bindings are performed in MAP.  The return value is non-zero if
     KEYSEQ is invalid.

 -- Function: int rl_set_key (const char *keyseq, rl_command_func_t
          *function, Keymap map)
     Equivalent to `rl_bind_keyseq_in_map'.

 -- Function: int rl_bind_keyseq_if_unbound (const char *keyseq,
          rl_command_func_t *function)
     Binds KEYSEQ to FUNCTION if it is not already bound in the
     currently active keymap.  Returns non-zero in the case of an
     invalid KEYSEQ or if KEYSEQ is already bound.

 -- Function: int rl_bind_keyseq_if_unbound_in_map (const char *keyseq,
          rl_command_func_t *function, Keymap map)
     Binds KEYSEQ to FUNCTION if it is not already bound in MAP.
     Returns non-zero in the case of an invalid KEYSEQ or if KEYSEQ is
     already bound.

 -- Function: int rl_generic_bind (int type, const 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; this can be a function (`ISFUNC'), a macro (`ISMACR'), or
     a keymap (`ISKMAP').  This makes new keymaps as necessary.  The
     initial keymap in which to do bindings is MAP.

 -- Function: int rl_parse_and_bind (char *line)
     Parse LINE as if it had been read from the `inputrc' file and
     perform any key bindings and variable assignments found (*note
     Readline Init File::).

 -- Function: int rl_read_init_file (const char *filename)
     Read keybindings and variable assignments from FILENAME (*note
     Readline Init File::).

\1f
File: readline.info,  Node: Associating Function Names and Bindings,  Next: Allowing Undoing,  Prev: Binding Keys,  Up: Readline Convenience Functions

2.4.4 Associating Function Names and Bindings
---------------------------------------------

These functions allow you to find out what keys invoke named functions
and the functions invoked by a particular key sequence.  You may also
associate a new function name with an arbitrary function.

 -- Function: rl_command_func_t * rl_named_function (const char *name)
     Return the function with name NAME.

 -- Function: rl_command_func_t * rl_function_of_keyseq (const char
          *keyseq, Keymap map, int *type)
     Return the function invoked by KEYSEQ in keymap MAP.  If MAP is
     `NULL', the current keymap is used.  If TYPE is not `NULL', the
     type of the object is returned in the `int' variable it points to
     (one of `ISFUNC', `ISKMAP', or `ISMACR').

 -- Function: char ** rl_invoking_keyseqs (rl_command_func_t *function)
     Return an array of strings representing the key sequences used to
     invoke FUNCTION in the current keymap.

 -- Function: char ** rl_invoking_keyseqs_in_map (rl_command_func_t
          *function, Keymap map)
     Return an array of strings representing the key sequences used to
     invoke FUNCTION in the keymap MAP.

 -- Function: void rl_function_dumper (int readable)
     Print the readline function names and the key sequences currently
     bound to them to `rl_outstream'.  If READABLE is non-zero, the
     list is formatted in such a way that it can be made part of an
     `inputrc' file and re-read.

 -- Function: void rl_list_funmap_names (void)
     Print the names of all bindable Readline functions to
     `rl_outstream'.

 -- Function: const char ** rl_funmap_names (void)
     Return a NULL terminated array of known function names.  The array
     is sorted.  The array itself is allocated, but not the strings
     inside.  You should `free()' the array when you are done, but not
     the pointers.

 -- Function: int rl_add_funmap_entry (const char *name,
          rl_command_func_t *function)
     Add NAME to the list of bindable Readline command names, and make
     FUNCTION the function to be called when NAME is invoked.

\1f
File: readline.info,  Node: Allowing Undoing,  Next: Redisplay,  Prev: Associating Function Names and Bindings,  Up: Readline Convenience Functions

2.4.5 Allowing Undoing
----------------------

Supporting the undo command is a painless thing, and makes your
functions much more useful.  It is certainly easy to try something if
you know you can undo it.

   If your function simply inserts text once, or deletes text once, and
uses `rl_insert_text()' or `rl_delete_text()' to do it, then undoing is
already done for you automatically.

   If you do multiple insertions or multiple deletions, or any
combination of these operations, you should group them together into
one operation.  This is done with `rl_begin_undo_group()' and
`rl_end_undo_group()'.

   The types of events that can be undone are:

     enum undo_code { UNDO_DELETE, UNDO_INSERT, UNDO_BEGIN, UNDO_END };

   Notice that `UNDO_DELETE' means to insert some text, and
`UNDO_INSERT' means to delete some text.  That is, the undo code tells
what to undo, not how to undo it.  `UNDO_BEGIN' and `UNDO_END' are tags
added by `rl_begin_undo_group()' and `rl_end_undo_group()'.

 -- Function: int rl_begin_undo_group (void)
     Begins saving undo information in a group construct.  The undo
     information usually comes from calls to `rl_insert_text()' and
     `rl_delete_text()', but could be the result of calls to
     `rl_add_undo()'.

 -- Function: int rl_end_undo_group (void)
     Closes the current undo group started with `rl_begin_undo_group
     ()'.  There should be one call to `rl_end_undo_group()' for each
     call to `rl_begin_undo_group()'.

 -- Function: void rl_add_undo (enum undo_code what, int start, int
          end, char *text)
     Remember how to undo an event (according to WHAT).  The affected
     text runs from START to END, and encompasses TEXT.

 -- Function: void rl_free_undo_list (void)
     Free the existing undo list.

 -- Function: int rl_do_undo (void)
     Undo the first thing on the undo list.  Returns `0' if there was
     nothing to undo, non-zero if something was undone.

   Finally, if you neither insert nor delete text, but directly modify
the existing text (e.g., change its case), 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: int 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 you will subsequently modify that
     text.

\1f
File: readline.info,  Node: Redisplay,  Next: Modifying Text,  Prev: Allowing Undoing,  Up: Readline Convenience Functions

2.4.6 Redisplay
---------------

 -- Function: void rl_redisplay (void)
     Change what's displayed on the screen to reflect the current
     contents of `rl_line_buffer'.

 -- Function: int rl_forced_update_display (void)
     Force the line to be updated and redisplayed, whether or not
     Readline thinks the screen display is correct.

 -- Function: int rl_on_new_line (void)
     Tell the update functions that we have moved onto a new (empty)
     line, usually after ouputting a newline.

 -- Function: int rl_on_new_line_with_prompt (void)
     Tell the update functions that we have moved onto a new line, with
     RL_PROMPT already displayed.  This could be used by applications
     that want to output the prompt string themselves, but still need
     Readline to know the prompt string length for redisplay.  It
     should be used after setting RL_ALREADY_PROMPTED.

 -- Function: int rl_reset_line_state (void)
     Reset the display state to a clean state and redisplay the current
     line starting on a new line.

 -- Function: int rl_crlf (void)
     Move the cursor to the start of the next screen line.

 -- Function: int rl_show_char (int c)
     Display character C on `rl_outstream'.  If Readline has not been
     set to display meta characters directly, this will convert meta
     characters to a meta-prefixed key sequence.  This is intended for
     use by applications which wish to do their own redisplay.

 -- Function: int rl_message (const char *, ...)
     The arguments are a format string as would be supplied to `printf',
     possibly containing conversion specifications such as `%d', and
     any additional arguments necessary to satisfy the conversion
     specifications.  The resulting string is displayed in the "echo
     area".  The echo area is also used to display numeric arguments
     and search strings.  You should call `rl_save_prompt' to save the
     prompt information before calling this function.

 -- Function: int rl_clear_message (void)
     Clear the message in the echo area.  If the prompt was saved with
     a call to `rl_save_prompt' before the last call to `rl_message',
     call `rl_restore_prompt' before calling this function.

 -- Function: void rl_save_prompt (void)
     Save the local Readline prompt display state in preparation for
     displaying a new message in the message area with `rl_message()'.

 -- Function: void rl_restore_prompt (void)
     Restore the local Readline prompt display state saved by the most
     recent call to `rl_save_prompt'.  if `rl_save_prompt' was called
     to save the prompt before a call to `rl_message', this function
     should be called before the corresponding call to
     `rl_clear_message'.

 -- Function: int rl_expand_prompt (char *prompt)
     Expand any special character sequences in PROMPT and set up the
     local Readline prompt redisplay variables.  This function is
     called by `readline()'.  It may also be called to expand the
     primary prompt if the `rl_on_new_line_with_prompt()' function or
     `rl_already_prompted' variable is used.  It returns the number of
     visible characters on the last line of the (possibly multi-line)
     prompt.  Applications may indicate that the prompt contains
     characters that take up no physical screen space when displayed by
     bracketing a sequence of such characters with the special markers
     `RL_PROMPT_START_IGNORE' and `RL_PROMPT_END_IGNORE' (declared in
     `readline.h'.  This may be used to embed terminal-specific escape
     sequences in prompts.

 -- Function: int rl_set_prompt (const char *prompt)
     Make Readline use PROMPT for subsequent redisplay.  This calls
     `rl_expand_prompt()' to expand the prompt and sets `rl_prompt' to
     the result.

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File: readline.info,  Node: Modifying Text,  Next: Character Input,  Prev: Redisplay,  Up: Readline Convenience Functions

2.4.7 Modifying Text
--------------------

 -- Function: int rl_insert_text (const char *text)
     Insert TEXT into the line at the current cursor position.  Returns
     the number of characters inserted.

 -- Function: int rl_delete_text (int start, int end)
     Delete the text between START and END in the current line.
     Returns the number of characters deleted.

 -- Function: char * rl_copy_text (int start, int end)
     Return a copy of the text between START and END in the current
     line.

 -- Function: int rl_kill_text (int start, int end)
     Copy the text between START and END in the current line to the
     kill ring, appending or prepending to the last kill if the last
     command was a kill command.  The text is deleted.  If START is
     less than END, the text is appended, otherwise prepended.  If the
     last command was not a kill, a new kill ring slot is used.

 -- Function: int rl_push_macro_input (char *macro)
     Cause MACRO to be inserted into the line, as if it had been invoked
     by a key bound to a macro.  Not especially useful; use
     `rl_insert_text()' instead.

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File: readline.info,  Node: Character Input,  Next: Terminal Management,  Prev: Modifying Text,  Up: Readline Convenience Functions

2.4.8 Character Input
---------------------

 -- Function: int rl_read_key (void)
     Return the next character available from Readline's current input
     stream.  This handles input inserted into the input stream via
     RL_PENDING_INPUT (*note Readline Variables::) and
     `rl_stuff_char()', macros, and characters read from the keyboard.
     While waiting for input, this function will call any function
     assigned to the `rl_event_hook' variable.

 -- Function: int rl_getc (FILE *stream)
     Return the next character available from STREAM, which is assumed
     to be the keyboard.

 -- Function: int rl_stuff_char (int c)
     Insert C into the Readline input stream.  It will be "read" before
     Readline attempts to read characters from the terminal with
     `rl_read_key()'.  Up to 512 characters may be pushed back.
     `rl_stuff_char' returns 1 if the character was successfully
     inserted; 0 otherwise.

 -- Function: int rl_execute_next (int c)
     Make C be the next command to be executed when `rl_read_key()' is
     called.  This sets RL_PENDING_INPUT.

 -- Function: int rl_clear_pending_input (void)
     Unset RL_PENDING_INPUT, effectively negating the effect of any
     previous call to `rl_execute_next()'.  This works only if the
     pending input has not already been read with `rl_read_key()'.

 -- Function: int rl_set_keyboard_input_timeout (int u)
     While waiting for keyboard input in `rl_read_key()', Readline will
     wait for U microseconds for input before calling any function
     assigned to `rl_event_hook'.  U must be greater than or equal to
     zero (a zero-length timeout is equivalent to a poll).  The default
     waiting period is one-tenth of a second.  Returns the old timeout
     value.

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File: readline.info,  Node: Terminal Management,  Next: Utility Functions,  Prev: Character Input,  Up: Readline Convenience Functions

2.4.9 Terminal Management
-------------------------

 -- Function: void rl_prep_terminal (int meta_flag)
     Modify the terminal settings for Readline's use, so `readline()'
     can read a single character at a time from the keyboard.  The
     META_FLAG argument should be non-zero if Readline should read
     eight-bit input.

 -- Function: void rl_deprep_terminal (void)
     Undo the effects of `rl_prep_terminal()', leaving the terminal in
     the state in which it was before the most recent call to
     `rl_prep_terminal()'.

 -- Function: void rl_tty_set_default_bindings (Keymap kmap)
     Read the operating system's terminal editing characters (as would
     be displayed by `stty') to their Readline equivalents.  The
     bindings are performed in KMAP.

 -- Function: void rl_tty_unset_default_bindings (Keymap kmap)
     Reset the bindings manipulated by `rl_tty_set_default_bindings' so
     that the terminal editing characters are bound to `rl_insert'.
     The bindings are performed in KMAP.

 -- Function: int rl_reset_terminal (const char *terminal_name)
     Reinitialize Readline's idea of the terminal settings using
     TERMINAL_NAME as the terminal type (e.g., `vt100').  If
     TERMINAL_NAME is `NULL', the value of the `TERM' environment
     variable is used.

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File: readline.info,  Node: Utility Functions,  Next: Miscellaneous Functions,  Prev: Terminal Management,  Up: Readline Convenience Functions

2.4.10 Utility Functions
------------------------

 -- Function: void rl_replace_line (const char *text, int clear_undo)
     Replace the contents of `rl_line_buffer' with TEXT.  The point and
     mark are preserved, if possible.  If CLEAR_UNDO is non-zero, the
     undo list associated with the current line is cleared.

 -- Function: int rl_extend_line_buffer (int len)
     Ensure that `rl_line_buffer' has enough space to hold LEN
     characters, possibly reallocating it if necessary.

 -- Function: int rl_initialize (void)
     Initialize or re-initialize Readline's internal state.  It's not
     strictly necessary to call this; `readline()' calls it before
     reading any input.

 -- Function: int rl_ding (void)
     Ring the terminal bell, obeying the setting of `bell-style'.

 -- Function: int rl_alphabetic (int c)
     Return 1 if C is an alphabetic character.

 -- Function: void rl_display_match_list (char **matches, int len, int
          max)
     A convenience function for displaying a list of strings in
     columnar format on Readline's output stream.  `matches' is the list
     of strings, in argv format, such as a list of completion matches.
     `len' is the number of strings in `matches', and `max' is the
     length of the longest string in `matches'.  This function uses the
     setting of `print-completions-horizontally' to select how the
     matches are displayed (*note Readline Init File Syntax::).

   The following are implemented as macros, defined in `chardefs.h'.
Applications should refrain from using them.

 -- Function: int _rl_uppercase_p (int c)
     Return 1 if C is an uppercase alphabetic character.

 -- Function: int _rl_lowercase_p (int c)
     Return 1 if C is a lowercase alphabetic character.

 -- Function: int _rl_digit_p (int c)
     Return 1 if C is a numeric character.

 -- Function: int _rl_to_upper (int c)
     If C is a lowercase alphabetic character, return the corresponding
     uppercase character.

 -- Function: int _rl_to_lower (int c)
     If C is an uppercase alphabetic character, return the corresponding
     lowercase character.

 -- Function: int _rl_digit_value (int c)
     If C is a number, return the value it represents.

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File: readline.info,  Node: Miscellaneous Functions,  Next: Alternate Interface,  Prev: Utility Functions,  Up: Readline Convenience Functions

2.4.11 Miscellaneous Functions
------------------------------

 -- Function: int rl_macro_bind (const char *keyseq, const char *macro,
          Keymap map)
     Bind the key sequence KEYSEQ to invoke the macro MACRO.  The
     binding is performed in MAP.  When KEYSEQ is invoked, the MACRO
     will be inserted into the line.  This function is deprecated; use
     `rl_generic_bind()' instead.

 -- Function: void rl_macro_dumper (int readable)
     Print the key sequences bound to macros and their values, using
     the current keymap, to `rl_outstream'.  If READABLE is non-zero,
     the list is formatted in such a way that it can be made part of an
     `inputrc' file and re-read.

 -- Function: int rl_variable_bind (const char *variable, const char
          *value)
     Make the Readline variable VARIABLE have VALUE.  This behaves as
     if the readline command `set VARIABLE VALUE' had been executed in
     an `inputrc' file (*note Readline Init File Syntax::).

 -- Function: char * rl_variable_value (const char *variable)
     Return a string representing the value of the Readline variable
     VARIABLE.  For boolean variables, this string is either `on' or
     `off'.

 -- Function: void rl_variable_dumper (int readable)
     Print the readline variable names and their current values to
     `rl_outstream'.  If READABLE is non-zero, the list is formatted in
     such a way that it can be made part of an `inputrc' file and
     re-read.

 -- Function: int rl_set_paren_blink_timeout (int u)
     Set the time interval (in microseconds) that Readline waits when
     showing a balancing character when `blink-matching-paren' has been
     enabled.

 -- Function: char * rl_get_termcap (const char *cap)
     Retrieve the string value of the termcap capability CAP.  Readline
     fetches the termcap entry for the current terminal name and uses
     those capabilities to move around the screen line and perform other
     terminal-specific operations, like erasing a line.  Readline does
     not use all of a terminal's capabilities, and this function will
     return values for only those capabilities Readline uses.

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File: readline.info,  Node: Alternate Interface,  Next: A Readline Example,  Prev: Miscellaneous Functions,  Up: Readline Convenience Functions

2.4.12 Alternate Interface
--------------------------

An alternate interface is available to plain `readline()'.  Some
applications need to interleave keyboard I/O with file, device, or
window system I/O, typically by using a main loop to `select()' on
various file descriptors.  To accomodate this need, readline can also
be invoked as a `callback' function from an event loop.  There are
functions available to make this easy.

 -- Function: void rl_callback_handler_install (const char *prompt,
          rl_vcpfunc_t *lhandler)
     Set up the terminal for readline I/O and display the initial
     expanded value of PROMPT.  Save the value of LHANDLER to use as a
     function to call when a complete line of input has been entered.
     The function takes the text of the line as an argument.

 -- Function: void rl_callback_read_char (void)
     Whenever an application determines that keyboard input is
     available, it should call `rl_callback_read_char()', which will
     read the next character from the current input source.  If that
     character completes the line, `rl_callback_read_char' will invoke
     the LHANDLER function saved by `rl_callback_handler_install' to
     process the line.  Before calling the LHANDLER function, the
     terminal settings are reset to the values they had before calling
     `rl_callback_handler_install'.  If the LHANDLER function returns,
     the terminal settings are modified for Readline's use again.
     `EOF' is  indicated by calling LHANDLER with a `NULL' line.

 -- Function: void rl_callback_handler_remove (void)
     Restore the terminal to its initial state and remove the line
     handler.  This may be called from within a callback as well as
     independently.  If the LHANDLER installed by
     `rl_callback_handler_install' does not exit the program, either
     this function or the function referred to by the value of
     `rl_deprep_term_function' should be called before the program
     exits to reset the terminal settings.

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File: readline.info,  Node: A Readline Example,  Prev: Alternate Interface,  Up: Readline Convenience Functions

2.4.13 A Readline Example
-------------------------

Here is a function which changes lowercase characters to their uppercase
equivalents, and uppercase characters to lowercase.  If this function
was bound to `M-c', then typing `M-c' would change the case of the
character under point.  Typing `M-1 0 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. */
     int
     invert_case_line (count, key)
          int count, key;
     {
       register int start, end, i;

       start = rl_point;

       if (rl_point >= rl_end)
         return (0);

       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 = 0;

       if (start == end)
         return (0);

       if (start > end)
         {
           int temp = start;
           start = end;
           end = temp;
         }

       /* Tell readline that we are modifying the line,
          so it will save the undo information. */
       rl_modifying (start, end);

       for (i = start; i != end; i++)
         {
           if (_rl_uppercase_p (rl_line_buffer[i]))
             rl_line_buffer[i] = _rl_to_lower (rl_line_buffer[i]);
           else if (_rl_lowercase_p (rl_line_buffer[i]))
             rl_line_buffer[i] = _rl_to_upper (rl_line_buffer[i]);
         }
       /* Move point to on top of the last character changed. */
       rl_point = (direction == 1) ? end - 1 : start;
       return (0);
     }

\1f
File: readline.info,  Node: Readline Signal Handling,  Next: Custom Completers,  Prev: Readline Convenience Functions,  Up: Programming with GNU Readline

2.5 Readline Signal Handling
============================

Signals are asynchronous events sent to a process by the Unix kernel,
sometimes on behalf of another process.  They are intended to indicate
exceptional events, like a user pressing the interrupt key on his
terminal, or a network connection being broken.  There is a class of
signals that can be sent to the process currently reading input from
the keyboard.  Since Readline changes the terminal attributes when it
is called, it needs to perform special processing when such a signal is
received in order to restore the terminal to a sane state, or provide
application writers with functions to do so manually.

   Readline contains an internal signal handler that is installed for a
number of signals (`SIGINT', `SIGQUIT', `SIGTERM', `SIGALRM',
`SIGTSTP', `SIGTTIN', and `SIGTTOU').  When one of these signals is
received, the signal handler will reset the terminal attributes to
those that were in effect before `readline()' was called, reset the
signal handling to what it was before `readline()' was called, and
resend the signal to the calling application.  If and when the calling
application's signal handler returns, Readline will reinitialize the
terminal and continue to accept input.  When a `SIGINT' is received,
the Readline signal handler performs some additional work, which will
cause any partially-entered line to be aborted (see the description of
`rl_free_line_state()' below).

   There is an additional Readline signal handler, for `SIGWINCH', which
the kernel sends to a process whenever the terminal's size changes (for
example, if a user resizes an `xterm').  The Readline `SIGWINCH'
handler updates Readline's internal screen size information, and then
calls any `SIGWINCH' signal handler the calling application has
installed.  Readline calls the application's `SIGWINCH' signal handler
without resetting the terminal to its original state.  If the
application's signal handler does more than update its idea of the
terminal size and return (for example, a `longjmp' back to a main
processing loop), it _must_ call `rl_cleanup_after_signal()' (described
below), to restore the terminal state.

   Readline provides two variables that allow application writers to
control whether or not it will catch certain signals and act on them
when they are received.  It is important that applications change the
values of these variables only when calling `readline()', not in a
signal handler, so Readline's internal signal state is not corrupted.

 -- Variable: int rl_catch_signals
     If this variable is non-zero, Readline will install signal
     handlers for `SIGINT', `SIGQUIT', `SIGTERM', `SIGALRM', `SIGTSTP',
     `SIGTTIN', and `SIGTTOU'.

     The default value of `rl_catch_signals' is 1.

 -- Variable: int rl_catch_sigwinch
     If this variable is non-zero, Readline will install a signal
     handler for `SIGWINCH'.

     The default value of `rl_catch_sigwinch' is 1.

   If an application does not wish to have Readline catch any signals,
or to handle signals other than those Readline catches (`SIGHUP', for
example), Readline provides convenience functions to do the necessary
terminal and internal state cleanup upon receipt of a signal.

 -- Function: void rl_cleanup_after_signal (void)
     This function will reset the state of the terminal to what it was
     before `readline()' was called, and remove the Readline signal
     handlers for all signals, depending on the values of
     `rl_catch_signals' and `rl_catch_sigwinch'.

 -- Function: void rl_free_line_state (void)
     This will free any partial state associated with the current input
     line (undo information, any partial history entry, any
     partially-entered keyboard macro, and any partially-entered
     numeric argument).  This should be called before
     `rl_cleanup_after_signal()'.  The Readline signal handler for
     `SIGINT' calls this to abort the current input line.

 -- Function: void rl_reset_after_signal (void)
     This will reinitialize the terminal and reinstall any Readline
     signal handlers, depending on the values of `rl_catch_signals' and
     `rl_catch_sigwinch'.

   If an application does not wish Readline to catch `SIGWINCH', it may
call `rl_resize_terminal()' or `rl_set_screen_size()' to force Readline
to update its idea of the terminal size when a `SIGWINCH' is received.

 -- Function: void rl_resize_terminal (void)
     Update Readline's internal screen size by reading values from the
     kernel.

 -- Function: void rl_set_screen_size (int rows, int cols)
     Set Readline's idea of the terminal size to ROWS rows and COLS
     columns.  If either ROWS or COLUMNS is less than or equal to 0,
     Readline's idea of that terminal dimension is unchanged.

   If an application does not want to install a `SIGWINCH' handler, but
is still interested in the screen dimensions, Readline's idea of the
screen size may be queried.

 -- Function: void rl_get_screen_size (int *rows, int *cols)
     Return Readline's idea of the terminal's size in the variables
     pointed to by the arguments.

 -- Function: void rl_reset_screen_size (void)
     Cause Readline to reobtain the screen size and recalculate its
     dimensions.

   The following functions install and remove Readline's signal
handlers.

 -- Function: int rl_set_signals (void)
     Install Readline's signal handler for `SIGINT', `SIGQUIT',
     `SIGTERM', `SIGALRM', `SIGTSTP', `SIGTTIN', `SIGTTOU', and
     `SIGWINCH', depending on the values of `rl_catch_signals' and
     `rl_catch_sigwinch'.

 -- Function: int rl_clear_signals (void)
     Remove all of the Readline signal handlers installed by
     `rl_set_signals()'.

\1f
File: readline.info,  Node: Custom Completers,  Prev: Readline Signal Handling,  Up: Programming with GNU Readline

2.6 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 commands, data, or both.  The following
sections describe how your program and Readline cooperate to provide
this service.

* 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.

\1f
File: readline.info,  Node: How Completing Works,  Next: Completion Functions,  Up: Custom Completers

2.6.1 How Completing Works
--------------------------

In order to complete some text, the full list of possible completions
must be available.  That is, it is not possible to accurately expand a
partial word without knowing all of the possible words which make sense
in that context.  The Readline library provides the user interface to
completion, and 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 such
functions must do, and provides an example.

   There are three major functions used to perform completion:

  1. The user-interface function `rl_complete()'.  This function is
     called with the same arguments as other bindable Readline
     functions: COUNT and INVOKING_KEY.  It isolates the word to be
     completed and calls `rl_completion_matches()' to generate a list
     of possible completions.  It then either lists the possible
     completions, inserts the possible completions, or actually
     performs the completion, depending on which behavior is desired.

  2. The internal function `rl_completion_matches()' uses an
     application-supplied "generator" function to generate the list of
     possible matches, and then returns the array of these matches.
     The caller should place the address of its generator function in
     `rl_completion_entry_function'.

  3. The generator function is called repeatedly from
     `rl_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, allowing the generator to perform any
     necessary initialization, and a positive non-zero integer for each
     subsequent call.  The generator function returns `(char *)NULL' to
     inform `rl_completion_matches()' that there are no more
     possibilities left.  Usually the generator function computes the
     list of possible completions when STATE is zero, and returns them
     one at a time on subsequent calls.  Each string the generator
     function returns as a match must be allocated with `malloc()';
     Readline frees the strings when it has finished with them.  Such a
     generator function is referred to as an "application-specific
     completion function".


 -- Function: int 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 `rl_completion_matches()').  The default is to do filename
     completion.

 -- Variable: rl_compentry_func_t * rl_completion_entry_function
     This is a pointer to the generator function for
     `rl_completion_matches()'.  If the value of
     `rl_completion_entry_function' is `NULL' then the default filename
     generator function, `rl_filename_completion_function()', is used.
     An "application-specific completion function" is a function whose
     address is assigned to `rl_completion_entry_function' and whose
     return values are used to  generate possible completions.

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File: readline.info,  Node: Completion Functions,  Next: Completion Variables,  Prev: How Completing Works,  Up: Custom Completers

2.6.2 Completion Functions
--------------------------

Here is the complete list of callable completion functions present in
Readline.

 -- Function: int 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.  `!' means to display all
     of the possible completions, if there is more than one, as well as
     performing partial completion.  `@' is similar to `!', but
     possible completions are not listed if the possible completions
     share a common prefix.

 -- Function: int 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 `rl_completion_matches()' and `rl_completion_entry_function').
     The default is to do filename completion.  This calls
     `rl_complete_internal()' with an argument depending on
     INVOKING_KEY.

 -- Function: int rl_possible_completions (int count, int invoking_key)
     List the possible completions.  See description of `rl_complete
     ()'.  This calls `rl_complete_internal()' with an argument of `?'.

 -- Function: int rl_insert_completions (int count, int invoking_key)
     Insert the list of possible completions into the line, deleting the
     partially-completed word.  See description of `rl_complete()'.
     This calls `rl_complete_internal()' with an argument of `*'.

 -- Function: int rl_completion_mode (rl_command_func_t *cfunc)
     Returns the apppriate value to pass to `rl_complete_internal()'
     depending on whether CFUNC was called twice in succession and the
     values of the `show-all-if-ambiguous' and `show-all-if-unmodified'
     variables.  Application-specific completion functions may use this
     function to present the same interface as `rl_complete()'.

 -- Function: char ** rl_completion_matches (const char *text,
          rl_compentry_func_t *entry_func)
     Returns an array of strings which is a list of completions for
     TEXT.  If there are no completions, returns `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_FUNC 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.
     ENTRY_FUNC returns a `NULL'  pointer to the caller when there are
     no more matches.

 -- Function: char * rl_filename_completion_function (const char *text,
          int state)
     A generator function for filename completion in the general case.
     TEXT is a partial filename.  The Bash source is a useful reference
     for writing application-specific completion functions (the Bash
     completion functions call this and other Readline functions).

 -- Function: char * rl_username_completion_function (const char *text,
          int state)
     A completion generator for usernames.  TEXT contains a partial
     username preceded by a random character (usually `~').  As with all
     completion generators, STATE is zero on the first call and non-zero
     for subsequent calls.

\1f
File: readline.info,  Node: Completion Variables,  Next: A Short Completion Example,  Prev: Completion Functions,  Up: Custom Completers

2.6.3 Completion Variables
--------------------------

 -- Variable: rl_compentry_func_t * rl_completion_entry_function
     A pointer to the generator function for `rl_completion_matches()'.
     `NULL' means to use `rl_filename_completion_function()', the
     default filename completer.

 -- Variable: rl_completion_func_t * 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' defining the boundaries of TEXT, which
     is a character string.  If this function exists and returns
     `NULL', or if this variable is set to `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.  If
     this function sets the `rl_attempted_completion_over' variable to
     a non-zero value, Readline will not perform its default completion
     even if this function returns no matches.

 -- Variable: rl_quote_func_t * rl_filename_quoting_function
     A pointer to a function that will quote a filename in an
     application-specific fashion.  This is called if filename
     completion is being attempted and one of the characters in
     `rl_filename_quote_characters' appears in a completed filename.
     The function is called with TEXT, MATCH_TYPE, and QUOTE_POINTER.
     The TEXT is the filename to be quoted.  The MATCH_TYPE is either
     `SINGLE_MATCH', if there is only one completion match, or
     `MULT_MATCH'.  Some functions use this to decide whether or not to
     insert a closing quote character.  The QUOTE_POINTER is a pointer
     to any opening quote character the user typed.  Some functions
     choose to reset this character.

 -- Variable: rl_dequote_func_t * rl_filename_dequoting_function
     A pointer to a function that will remove application-specific
     quoting characters from a filename before completion is attempted,
     so those characters do not interfere with matching the text
     against names in the filesystem.  It is called with TEXT, the text
     of the word to be dequoted, and QUOTE_CHAR, which is the quoting
     character that delimits the filename (usually `'' or `"').  If
     QUOTE_CHAR is zero, the filename was not in an embedded string.

 -- Variable: rl_linebuf_func_t * rl_char_is_quoted_p
     A pointer to a function to call that determines whether or not a
     specific character in the line buffer is quoted, according to
     whatever quoting mechanism the program calling Readline uses.  The
     function is called with two arguments: TEXT, the text of the line,
     and INDEX, the index of the character in the line.  It is used to
     decide whether a character found in
     `rl_completer_word_break_characters' should be used to break words
     for the completer.

 -- Variable: rl_compignore_func_t * 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 matches.
     The first element (`matches[0]') is the maximal substring common
     to all matches. This function can re-arrange the list of matches
     as required, but each element deleted from the array must be freed.

 -- Variable: rl_icppfunc_t * rl_directory_completion_hook
     This function, if defined, is allowed to modify the directory
     portion of filenames Readline completes.  It is called with the
     address of a string (the current directory name) as an argument,
     and may modify that string.  If the string is replaced with a new
     string, the old value should be freed.  Any modified directory
     name should have a trailing slash.  The modified value will be
     displayed as part of the completion, replacing the directory
     portion of the pathname the user typed.  It returns an integer
     that should be non-zero if the function modifies its directory
     argument.  It could be used to expand symbolic links or shell
     variables in pathnames.  At the least, even if no other expansion
     is performed, this function should remove any quote characters
     from the directory name, because its result will be passed
     directly to `opendir()'.

 -- Variable: rl_compdisp_func_t * rl_completion_display_matches_hook
     If non-zero, then this is the address of a function to call when
     completing a word would normally display the list of possible
     matches.  This function is called in lieu of Readline displaying
     the list.  It takes three arguments: (`char **'MATCHES, `int'
     NUM_MATCHES, `int' MAX_LENGTH) where MATCHES is the array of
     matching strings, NUM_MATCHES is the number of strings in that
     array, and MAX_LENGTH is the length of the longest string in that
     array.  Readline provides a convenience function,
     `rl_display_match_list', that takes care of doing the display to
     Readline's output stream.  That function may be called from this
     hook.

 -- Variable: const char * rl_basic_word_break_characters
     The basic list of characters that signal a break between words for
     the completer routine.  The default value of this variable is the
     characters which break words for completion in Bash: `"
     \t\n\"\\'`@$><=;|&{("'.

 -- Variable: const char * rl_basic_quote_characters
     A list of quote characters which can cause a word break.

 -- Variable: const 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 value of
     `rl_basic_word_break_characters'.

 -- Variable: rl_cpvfunc_t * rl_completion_word_break_hook
     If non-zero, this is the address of a function to call when
     Readline is deciding where to separate words for word completion.
     It should return a character string like
     `rl_completer_word_break_characters' to be used to perform the
     current completion.  The function may choose to set
     `rl_completer_word_break_characters' itself.  If the function
     returns `NULL', `rl_completer_word_break_characters' is used.

 -- Variable: const char * rl_completer_quote_characters
     A list of characters which can be used to quote a substring of the
     line.  Completion occurs on the entire substring, and within the
     substring `rl_completer_word_break_characters' are treated as any
     other character, unless they also appear within this list.

 -- Variable: const char * rl_filename_quote_characters
     A list of characters that cause a filename to be quoted by the
     completer when they appear in a completed filename.  The default
     is the null string.

 -- Variable: const 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.  For instance, Bash sets this variable to "$@" so that it can
     complete shell variables and hostnames.

 -- Variable: int rl_completion_query_items
     Up to this many items will be displayed in response to a
     possible-completions call.  After that, readline asks the user if
     she is sure she wants to see them all.  The default value is 100.
     A negative value indicates that Readline should never ask the user.

 -- Variable: int rl_completion_append_character
     When a single completion alternative matches at the end of the
     command line, this character is appended to the inserted
     completion text.  The default is a space character (` ').  Setting
     this to the null character (`\0') prevents anything being appended
     automatically.  This can be changed in application-specific
     completion functions to provide the "most sensible word separator
     character" according to an application-specific command line
     syntax specification.

 -- Variable: int rl_completion_suppress_append
     If non-zero, RL_COMPLETION_APPEND_CHARACTER is not appended to
     matches at the end of the command line, as described above.  It is
     set to 0 before any application-specific completion function is
     called, and may only be changed within such a function.

 -- Variable: int rl_completion_quote_character
     When Readline is completing quoted text, as delimited by one of the
     characters in RL_COMPLETER_QUOTE_CHARACTERS, it sets this variable
     to the quoting character found.  This is set before any
     application-specific completion function is called.

 -- Variable: int rl_completion_suppress_quote
     If non-zero, Readline does not append a matching quote character
     when performing completion on a quoted string.  It is set to 0
     before any application-specific completion function is called, and
     may only be changed within such a function.

 -- Variable: int rl_completion_found_quote
     When Readline is completing quoted text, it sets this variable to
     a non-zero value if the word being completed contains or is
     delimited by any quoting characters, including backslashes.  This
     is set before any application-specific completion function is
     called.

 -- Variable: int rl_completion_mark_symlink_dirs
     If non-zero, a slash will be appended to completed filenames that
     are symbolic links to directory names, subject to the value of the
     user-settable MARK-DIRECTORIES variable.  This variable exists so
     that application-specific completion functions can override the
     user's global preference (set via the MARK-SYMLINKED-DIRECTORIES
     Readline variable) if appropriate.  This variable is set to the
     user's preference before any application-specific completion
     function is called, so unless that function modifies the value,
     the user's preferences are honored.

 -- Variable: int rl_ignore_completion_duplicates
     If non-zero, then duplicates in the matches are removed.  The
     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 when completion is attempted,
     and can only be changed within an application-specific completion
     function.  If it is set to a non-zero value by such a function,
     directory names have a slash appended and Readline attempts to
     quote completed filenames if they contain any characters in
     `rl_filename_quote_characters' and `rl_filename_quoting_desired'
     is set to a non-zero value.

 -- Variable: int rl_filename_quoting_desired
     Non-zero means that the results of the matches are to be quoted
     using double quotes (or an application-specific quoting mechanism)
     if the completed filename contains any characters in
     `rl_filename_quote_chars'.  This is _always_ non-zero when
     completion is attempted, and can only be changed within an
     application-specific completion function.  The quoting is effected
     via a call to the function pointed to by
     `rl_filename_quoting_function'.

 -- Variable: int rl_attempted_completion_over
     If an application-specific completion function assigned to
     `rl_attempted_completion_function' sets this variable to a non-zero
     value, Readline will not perform its default filename completion
     even if the application's completion function returns no matches.
     It should be set only by an application's completion function.

 -- Variable: int rl_completion_type
     Set to a character describing the type of completion Readline is
     currently attempting; see the description of
     `rl_complete_internal()' (*note Completion Functions::) for the
     list of characters.  This is set to the appropriate value before
     any application-specific completion function is called, allowing
     such functions to present the same interface as `rl_complete()'.

 -- Variable: int rl_inhibit_completion
     If this variable is non-zero, completion is inhibited.  The
     completion character will be inserted as any other bound to
     `self-insert'.

\1f
File: readline.info,  Node: A Short Completion Example,  Prev: Completion Variables,  Up: Custom Completers

2.6.4 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
`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 <sys/types.h>
     #include <sys/file.h>
     #include <sys/stat.h>
     #include <sys/errno.h>

     #include <readline/readline.h>
     #include <readline/history.h>

     extern char *xmalloc ();

     /* The names of functions that actually do the manipulation. */
     int com_list __P((char *));
     int com_view __P((char *));
     int com_rename __P((char *));
     int com_stat __P((char *));
     int com_pwd __P((char *));
     int com_delete __P((char *));
     int com_help __P((char *));
     int com_cd __P((char *));
     int com_quit __P((char *));

     /* A structure which contains information on the commands this program
        can understand. */

     typedef struct {
       char *name;                      /* User printable name of the function. */
       rl_icpfunc_t *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, (rl_icpfunc_t *)NULL, (char *)NULL }
     };

     /* Forward declarations. */
     char *stripwhite ();
     COMMAND *find_command ();

     /* The name of this program, as taken from argv[0]. */
     char *progname;

     /* When non-zero, this means the user is done using this program. */
     int done;

     char *
     dupstr (s)
          int s;
     {
       char *r;

       r = xmalloc (strlen (s) + 1);
       strcpy (r, s);
       return (r);
     }

     main (argc, argv)
          int argc;
          char **argv;
     {
       char *line, *s;

       progname = argv[0];

       initialize_readline ();  /* Bind our completer. */

       /* Loop reading and executing lines until the user quits. */
       for ( ; done == 0; )
         {
           line = readline ("FileMan: ");

           if (!line)
             break;

           /* Remove leading and trailing whitespace from the line.
              Then, if there is anything left, add it to the history list
              and execute it. */
           s = stripwhite (line);

           if (*s)
             {
               add_history (s);
               execute_line (s);
             }

           free (line);
         }
       exit (0);
     }

     /* Execute a command line. */
     int
     execute_line (line)
          char *line;
     {
       register int i;
       COMMAND *command;
       char *word;

       /* Isolate the command word. */
       i = 0;
       while (line[i] && whitespace (line[i]))
         i++;
       word = line + i;

       while (line[i] && !whitespace (line[i]))
         i++;

       if (line[i])
         line[i++] = '\0';

       command = find_command (word);

       if (!command)
         {
           fprintf (stderr, "%s: No such command for FileMan.\n", word);
           return (-1);
         }

       /* Get argument to command, if any. */
       while (whitespace (line[i]))
         i++;

       word = line + i;

       /* Call the function. */
       return ((*(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.  Return a pointer
        into STRING. */
     char *
     stripwhite (string)
          char *string;
     {
       register char *s, *t;

       for (s = string; whitespace (*s); s++)
         ;

       if (*s == 0)
         return (s);

       t = s + strlen (s) - 1;
       while (t > s && whitespace (*t))
         t--;
       *++t = '\0';

       return s;
     }

     /* **************************************************************** */
     /*                                                                  */
     /*                  Interface to Readline Completion                */
     /*                                                                  */
     /* **************************************************************** */

     char *command_generator __P((const char *, int));
     char **fileman_completion __P((const char *, int, int));

     /* 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 ()
     {
       /* Allow conditional parsing of the ~/.inputrc file. */
       rl_readline_name = "FileMan";

       /* Tell the completer that we want a crack first. */
       rl_attempted_completion_function = fileman_completion;
     }

     /* Attempt to complete on the contents of TEXT.  START and END
        bound the region of rl_line_buffer that contains the word to
        complete.  TEXT is the word to complete.  We can use the entire
        contents of rl_line_buffer in case we want to do some simple
        parsing.  Returnthe array of matches, or NULL if there aren't any. */
     char **
     fileman_completion (text, start, end)
          const char *text;
          int start, end;
     {
       char **matches;

       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 = rl_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)
          const 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 (dupstr(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);
       return (system (syscom));
     }

     com_view (arg)
          char *arg;
     {
       if (!valid_argument ("view", arg))
         return 1;

       sprintf (syscom, "more %s", arg);
       return (system (syscom));
     }

     com_rename (arg)
          char *arg;
     {
       too_dangerous ("rename");
       return (1);
     }

     com_stat (arg)
          char *arg;
     {
       struct stat finfo;

       if (!valid_argument ("stat", arg))
         return (1);

       if (stat (arg, &finfo) == -1)
         {
           perror (arg);
           return (1);
         }

       printf ("Statistics for `%s':\n", arg);

       printf ("%s has %d link%s, and is %d byte%s in length.\n", arg,
               finfo.st_nlink,
               (finfo.st_nlink == 1) ? "" : "s",
               finfo.st_size,
               (finfo.st_size == 1) ? "" : "s");
       printf ("Inode Last Change at: %s", ctime (&finfo.st_ctime));
       printf ("      Last access at: %s", ctime (&finfo.st_atime));
       printf ("    Last modified at: %s", ctime (&finfo.st_mtime));
       return (0);
     }

     com_delete (arg)
          char *arg;
     {
       too_dangerous ("delete");
       return (1);
     }

     /* 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");
         }
       return (0);
     }

     /* Change to the directory ARG. */
     com_cd (arg)
          char *arg;
     {
       if (chdir (arg) == -1)
         {
           perror (arg);
           return 1;
         }

       com_pwd ("");
       return (0);
     }

     /* Print out the current working directory. */
     com_pwd (ignore)
          char *ignore;
     {
       char dir[1024], *s;

       s = getcwd (dir, sizeof(dir) - 1);
       if (s == 0)
         {
           printf ("Error getting pwd: %s\n", dir);
           return 1;
         }

       printf ("Current directory is %s\n", dir);
       return 0;
     }

     /* The user wishes to quit using this program.  Just set DONE
        non-zero. */
     com_quit (arg)
          char *arg;
     {
       done = 1;
       return (0);
     }

     /* Function which tells you that you can't do this. */
     too_dangerous (caller)
          char *caller;
     {
       fprintf (stderr,
                "%s: Too dangerous for me to distribute.\n",
                caller);
       fprintf (stderr, "Write it yourself.\n");
     }

     /* 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);
     }

\1f
File: readline.info,  Node: Copying This Manual,  Next: Concept Index,  Prev: Programming with GNU Readline,  Up: Top

Appendix A Copying This Manual
******************************

* Menu:

* GNU Free Documentation License::      License for copying this manual.

\1f
File: readline.info,  Node: GNU Free Documentation License,  Up: Copying This Manual

A.1 GNU Free Documentation License
==================================

                      Version 1.2, November 2002

     Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
     59 Temple Place, Suite 330, Boston, MA  02111-1307, USA

     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.

  0. PREAMBLE

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     functional and useful document "free" in the sense of freedom: to
     assure everyone the effective freedom to copy and redistribute it,
     with or without modifying it, either commercially or
     noncommercially.  Secondarily, this License preserves for the
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     being considered responsible for modifications made by others.

     This License is a kind of "copyleft", which means that derivative
     works of the document must themselves be free in the same sense.
     It complements the GNU General Public License, which is a copyleft
     license designed for free software.

     We have designed this License in order to use it for manuals for
     free software, because free software needs free documentation: a
     free program should come with manuals providing the same freedoms
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     Warranty Disclaimers are considered to be included by reference in
     this License, but only as regards disclaiming warranties: any other
     implication that these Warranty Disclaimers may have is void and
     has no effect on the meaning of this License.

  2. VERBATIM COPYING

     You may copy and distribute the Document in any medium, either
     commercially or noncommercially, provided that this License, the
     copyright notices, and the license notice saying this License
     applies to the Document are reproduced in all copies, and that you
     add no other conditions whatsoever to those of this License.  You
     may not use technical measures to obstruct or control the reading
     or further copying of the copies you make or distribute.  However,
     you may accept compensation in exchange for copies.  If you
     distribute a large enough number of copies you must also follow
     the conditions in section 3.

     You may also lend copies, under the same conditions stated above,
     and you may publicly display copies.

  3. COPYING IN QUANTITY

     If you publish printed copies (or copies in media that commonly
     have printed covers) of the Document, numbering more than 100, and
     the Document's license notice requires Cover Texts, you must
     enclose the copies in covers that carry, clearly and legibly, all
     these Cover Texts: Front-Cover Texts on the front cover, and
     Back-Cover Texts on the back cover.  Both covers must also clearly
     and legibly identify you as the publisher of these copies.  The
     front cover must present the full title with all words of the
     title equally prominent and visible.  You may add other material
     on the covers in addition.  Copying with changes limited to the
     covers, as long as they preserve the title of the Document and
     satisfy these conditions, can be treated as verbatim copying in
     other respects.

     If the required texts for either cover are too voluminous to fit
     legibly, you should put the first ones listed (as many as fit
     reasonably) on the actual cover, and continue the rest onto
     adjacent pages.

     If you publish or distribute Opaque copies of the Document
     numbering more than 100, you must either include a
     machine-readable Transparent copy along with each Opaque copy, or
     state in or with each Opaque copy a computer-network location from
     which the general network-using public has access to download
     using public-standard network protocols a complete Transparent
     copy of the Document, free of added material.  If you use the
     latter option, you must take reasonably prudent steps, when you
     begin distribution of Opaque copies in quantity, to ensure that
     this Transparent copy will remain thus accessible at the stated
     location until at least one year after the last time you
     distribute an Opaque copy (directly or through your agents or
     retailers) of that edition to the public.

     It is requested, but not required, that you contact the authors of
     the Document well before redistributing any large number of
     copies, to give them a chance to provide you with an updated
     version of the Document.

  4. MODIFICATIONS

     You may copy and distribute a Modified Version of the Document
     under the conditions of sections 2 and 3 above, provided that you
     release the Modified Version under precisely this License, with
     the Modified Version filling the role of the Document, thus
     licensing distribution and modification of the Modified Version to
     whoever possesses a copy of it.  In addition, you must do these
     things in the Modified Version:

       A. Use in the Title Page (and on the covers, if any) a title
          distinct from that of the Document, and from those of
          previous versions (which should, if there were any, be listed
          in the History section of the Document).  You may use the
          same title as a previous version if the original publisher of
          that version gives permission.

       B. List on the Title Page, as authors, one or more persons or
          entities responsible for authorship of the modifications in
          the Modified Version, together with at least five of the
          principal authors of the Document (all of its principal
          authors, if it has fewer than five), unless they release you
          from this requirement.

       C. State on the Title page the name of the publisher of the
          Modified Version, as the publisher.

       D. Preserve all the copyright notices of the Document.

       E. Add an appropriate copyright notice for your modifications
          adjacent to the other copyright notices.

       F. Include, immediately after the copyright notices, a license
          notice giving the public permission to use the Modified
          Version under the terms of this License, in the form shown in
          the Addendum below.

       G. Preserve in that license notice the full lists of Invariant
          Sections and required Cover Texts given in the Document's
          license notice.

       H. Include an unaltered copy of this License.

       I. Preserve the section Entitled "History", Preserve its Title,
          and add to it an item stating at least the title, year, new
          authors, and publisher of the Modified Version as given on
          the Title Page.  If there is no section Entitled "History" in
          the Document, create one stating the title, year, authors,
          and publisher of the Document as given on its Title Page,
          then add an item describing the Modified Version as stated in
          the previous sentence.

       J. Preserve the network location, if any, given in the Document
          for public access to a Transparent copy of the Document, and
          likewise the network locations given in the Document for
          previous versions it was based on.  These may be placed in
          the "History" section.  You may omit a network location for a
          work that was published at least four years before the
          Document itself, or if the original publisher of the version
          it refers to gives permission.

       K. For any section Entitled "Acknowledgements" or "Dedications",
          Preserve the Title of the section, and preserve in the
          section all the substance and tone of each of the contributor
          acknowledgements and/or dedications given therein.

       L. Preserve all the Invariant Sections of the Document,
          unaltered in their text and in their titles.  Section numbers
          or the equivalent are not considered part of the section
          titles.

       M. Delete any section Entitled "Endorsements".  Such a section
          may not be included in the Modified Version.

       N. Do not retitle any existing section to be Entitled
          "Endorsements" or to conflict in title with any Invariant
          Section.

       O. Preserve any Warranty Disclaimers.

     If the Modified Version includes new front-matter sections or
     appendices that qualify as Secondary Sections and contain no
     material copied from the Document, you may at your option
     designate some or all of these sections as invariant.  To do this,
     add their titles to the list of Invariant Sections in the Modified
     Version's license notice.  These titles must be distinct from any
     other section titles.

     You may add a section Entitled "Endorsements", provided it contains
     nothing but endorsements of your Modified Version by various
     parties--for example, statements of peer review or that the text
     has been approved by an organization as the authoritative
     definition of a standard.

     You may add a passage of up to five words as a Front-Cover Text,
     and a passage of up to 25 words as a Back-Cover Text, to the end
     of the list of Cover Texts in the Modified Version.  Only one
     passage of Front-Cover Text and one of Back-Cover Text may be
     added by (or through arrangements made by) any one entity.  If the
     Document already includes a cover text for the same cover,
     previously added by you or by arrangement made by the same entity
     you are acting on behalf of, you may not add another; but you may
     replace the old one, on explicit permission from the previous
     publisher that added the old one.

     The author(s) and publisher(s) of the Document do not by this
     License give permission to use their names for publicity for or to
     assert or imply endorsement of any Modified Version.

  5. COMBINING DOCUMENTS

     You may combine the Document with other documents released under
     this License, under the terms defined in section 4 above for
     modified versions, provided that you include in the combination
     all of the Invariant Sections of all of the original documents,
     unmodified, and list them all as Invariant Sections of your
     combined work in its license notice, and that you preserve all
     their Warranty Disclaimers.

     The combined work need only contain one copy of this License, and
     multiple identical Invariant Sections may be replaced with a single
     copy.  If there are multiple Invariant Sections with the same name
     but different contents, make the title of each such section unique
     by adding at the end of it, in parentheses, the name of the
     original author or publisher of that section if known, or else a
     unique number.  Make the same adjustment to the section titles in
     the list of Invariant Sections in the license notice of the
     combined work.

     In the combination, you must combine any sections Entitled
     "History" in the various original documents, forming one section
     Entitled "History"; likewise combine any sections Entitled
     "Acknowledgements", and any sections Entitled "Dedications".  You
     must delete all sections Entitled "Endorsements."

  6. COLLECTIONS OF DOCUMENTS

     You may make a collection consisting of the Document and other
     documents released under this License, and replace the individual
     copies of this License in the various documents with a single copy
     that is included in the collection, provided that you follow the
     rules of this License for verbatim copying of each of the
     documents in all other respects.

     You may extract a single document from such a collection, and
     distribute it individually under this License, provided you insert
     a copy of this License into the extracted document, and follow
     this License in all other respects regarding verbatim copying of
     that document.

  7. AGGREGATION WITH INDEPENDENT WORKS

     A compilation of the Document or its derivatives with other
     separate and independent documents or works, in or on a volume of
     a storage or distribution medium, is called an "aggregate" if the
     copyright resulting from the compilation is not used to limit the
     legal rights of the compilation's users beyond what the individual
     works permit.  When the Document is included an aggregate, this
     License does not apply to the other works in the aggregate which
     are not themselves derivative works of the Document.

     If the Cover Text requirement of section 3 is applicable to these
     copies of the Document, then if the Document is less than one half
     of the entire aggregate, the Document's Cover Texts may be placed
     on covers that bracket the Document within the aggregate, or the
     electronic equivalent of covers if the Document is in electronic
     form.  Otherwise they must appear on printed covers that bracket
     the whole aggregate.

  8. TRANSLATION

     Translation is considered a kind of modification, so you may
     distribute translations of the Document under the terms of section
     4.  Replacing Invariant Sections with translations requires special
     permission from their copyright holders, but you may include
     translations of some or all Invariant Sections in addition to the
     original versions of these Invariant Sections.  You may include a
     translation of this License, and all the license notices in the
     Document, and any Warranty Disclaimers, provided that you also
     include the original English version of this License and the
     original versions of those notices and disclaimers.  In case of a
     disagreement between the translation and the original version of
     this License or a notice or disclaimer, the original version will
     prevail.

     If a section in the Document is Entitled "Acknowledgements",
     "Dedications", or "History", the requirement (section 4) to
     Preserve its Title (section 1) will typically require changing the
     actual title.

  9. TERMINATION

     You may not copy, modify, sublicense, or distribute the Document
     except as expressly provided for under this License.  Any other
     attempt to copy, modify, sublicense or distribute the Document is
     void, and will automatically terminate your rights under this
     License.  However, parties who have received copies, or rights,
     from you under this License will not have their licenses
     terminated so long as such parties remain in full compliance.

 10. FUTURE REVISIONS OF THIS LICENSE

     The Free Software Foundation may publish new, revised versions of
     the GNU Free Documentation License from time to time.  Such new
     versions will be similar in spirit to the present version, but may
     differ in detail to address new problems or concerns.  See
     `http://www.gnu.org/copyleft/'.

     Each version of the License is given a distinguishing version
     number.  If the Document specifies that a particular numbered
     version of this License "or any later version" applies to it, you
     have the option of following the terms and conditions either of
     that specified version or of any later version that has been
     published (not as a draft) by the Free Software Foundation.  If
     the Document does not specify a version number of this License,
     you may choose any version ever published (not as a draft) by the
     Free Software Foundation.

A.1.1 ADDENDUM: How to use this License for your documents
----------------------------------------------------------

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:

       Copyright (C)  YEAR  YOUR NAME.
       Permission is granted to copy, distribute and/or modify this document
       under the terms of the GNU Free Documentation License, Version 1.2
       or any later version published by the Free Software Foundation;
       with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
       A copy of the license is included in the section entitled ``GNU
       Free Documentation License''.

   If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the "with...Texts." line with this:

         with the Invariant Sections being LIST THEIR TITLES, with
         the Front-Cover Texts being LIST, and with the Back-Cover Texts
         being LIST.

   If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.

   If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License, to
permit their use in free software.

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