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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. The Readline home page is http://www.gnu.org/software/readline/.
1. Command Line Editing GNU Readline User's Manual. 2. Programming with GNU Readline GNU Readline Programmer's Manual. A. GNU Free Documentation License License for 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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This chapter describes the basic features of the GNU command line editing interface.
1.1 Introduction to Line Editing Notation used in this text. 1.2 Readline Interaction The minimum set of commands for editing a line. 1.3 Readline Init File Customizing Readline from a user's view. 1.4 Bindable Readline Commands A description of most of the Readline commands available for binding 1.5 Readline vi Mode A short description of how to make Readline behave like the vi editor.
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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 (see section 1.3 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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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.
1.2.1 Readline Bare Essentials The least you need to know about Readline. 1.2.2 Readline Movement Commands Moving about the input line. 1.2.3 Readline Killing Commands How to delete text, and how to get it back! 1.2.4 Readline Arguments Giving numeric arguments to commands. 1.2.5 Searching for Commands in the History Searching through previous lines.
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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.
(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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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.
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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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.
Here is how to yank the text back into the line. Yanking means to copy the most-recently-killed text from the kill buffer.
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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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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-rs 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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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.
1.3.1 Readline Init File Syntax Syntax for the commands in the inputrc file.
1.3.2 Conditional Init Constructs Conditional key bindings in the inputrc file.
1.3.3 Sample Init File An example inputrc file.
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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 (see section 1.3.2 Conditional Init Constructs). Other lines denote variable settings and key bindings.
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
bind-tty-special-chars
blink-matching-paren
colored-completion-prefix
LS_COLORS
environment variable.
The default is `off'.
colored-stats
LS_COLORS
environment variable.
The default is `off'.
comment-begin
insert-comment command is executed. The default value
is "#".
completion-display-width
completion-ignore-case
completion-map-case
completion-prefix-display-length
completion-query-items
100.
convert-meta
disable-completion
self-insert. The default is `off'.
echo-control-characters
editing-mode
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'.
emacs-mode-string
enable-bracketed-paste
enable-keypad
enable-meta-key
expand-tilde
history-preserve-point
previous-history
or next-history. The default is `off'.
history-size
horizontal-scroll-mode
input-meta
meta-flag is a synonym for this variable.
isearch-terminators
keymap
keymap names are
emacs,
emacs-standard,
emacs-meta,
emacs-ctlx,
vi,
vi-move,
vi-command, and
vi-insert.
vi is equivalent to vi-command (vi-move is also a
synonym); emacs is equivalent to emacs-standard.
Applications may add additional names.
The default value is emacs.
The value of the editing-mode variable also affects the
default keymap.
keyseq-timeout
rl_instream by default).
The value is specified in milliseconds, so a value of 1000 means that
Readline will wait one second for additional input.
If this variable is set to a value less than or equal to zero, or to a
non-numeric value, Readline will wait until another key is pressed to
decide which key sequence to complete.
The default value is 500.
mark-directories
mark-modified-lines
mark-symlinked-directories
mark-directories).
The default is `off'.
match-hidden-files
menu-complete-display-prefix
output-meta
page-completions
more-like pager
to display a screenful of possible completions at a time.
This variable is `on' by default.
print-completions-horizontally
revert-all-at-newline
accept-line is executed. By default,
history lines may be modified and retain individual undo lists across
calls to readline. The default is `off'.
show-all-if-ambiguous
show-all-if-unmodified
show-mode-in-prompt
skip-completed-text
vi-cmd-mode-string
vi-ins-mode-string
visible-stats
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. There can be no space between the key name and the colon -- that will be interpreted as part of the key name. 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).
Control-u: universal-argument Meta-Rubout: backward-kill-word Control-o: "> output" |
In the example above, 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.
"\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-
\M-
\e
\\
\"
\'
In addition to the GNU Emacs style escape sequences, a second set of backslash escapes is available:
\a
\b
\d
\f
\n
\r
\t
\v
\nnn
\xHH
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\\": "\\" |
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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
$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, after any comparison operator,
extends to the end of the line;
unless otherwise noted, no characters are required to isolate it.
mode
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
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.
version
version test may be used to perform comparisons against
specific Readline versions.
The version expands to the current Readline version.
The set of comparison operators includes
`=' (and `=='), `!=', `<=', `>=', `<',
and `>'.
The version number supplied on the right side of the operator consists
of a major version number, an optional decimal point, and an optional
minor version (e.g., `7.1'). If the minor version is omitted, it
is assumed to be `0'.
The operator may be separated from the string version and
from the version number argument by whitespace.
The following example sets a variable if the Readline version being used
is 7.0 or newer:
$if version >= 7.0 set show-mode-in-prompt on $endif |
application
$if Bash # Quote the current or previous word "\C-xq": "\eb\"\ef\"" $endif |
variable
mode=emacs test described
above:
$if editing-mode == emacs set show-mode-in-prompt on $endif |
$endif
$if command.
$else
$if directive are executed if
the test fails.
$include
$include /etc/inputrc |
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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 system-wide 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 150 or more possible completions for a word,
# ask whether or not the user 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
|
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1.4.1 Commands For Moving Moving about the line. 1.4.2 Commands For Manipulating The History Getting at previous lines. 1.4.3 Commands For Changing Text Commands for changing text. 1.4.4 Killing And Yanking Commands for killing and yanking. 1.4.5 Specifying Numeric Arguments Specifying numeric arguments, repeat counts. 1.4.6 Letting Readline Type For You Getting Readline to do the typing for you. 1.4.7 Keyboard Macros Saving and re-executing typed characters 1.4.8 Some 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.
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beginning-of-line (C-a)
end-of-line (C-e)
forward-char (C-f)
backward-char (C-b)
forward-word (M-f)
backward-word (M-b)
previous-screen-line ()
next-screen-line ()
clear-display (M-C-l)
clear-screen (C-l)
redraw-current-line ()
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accept-line (Newline or Return)
add_history().
If this line is a modified history line, the history line is restored
to its original state.
previous-history (C-p)
next-history (C-n)
beginning-of-history (M-<)
end-of-history (M->)
reverse-search-history (C-r)
forward-search-history (C-s)
non-incremental-reverse-search-history (M-p)
non-incremental-forward-search-history (M-n)
history-search-forward ()
history-search-backward ()
history-substring-search-forward ()
history-substring-search-backward ()
yank-nth-arg (M-C-y)
yank-last-arg (M-. or M-_)
yank-nth-arg.
Successive calls to yank-last-arg move back through the history
list, inserting the last word (or the word specified by the argument to
the first call) of each line in turn.
Any numeric argument supplied to these successive calls determines
the direction to move through the history. A negative argument switches
the direction through the history (back or forward).
The history expansion facilities are used to extract the last argument,
as if the `!$' history expansion had been specified.
operate-and-get-next (C-o)
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end-of-file (usually C-d)
stty. If this character is read when there are no characters
on the line, and point is at the beginning of the line, Readline
interprets it as the end of input and returns EOF.
delete-char (C-d)
backward-delete-char (Rubout)
forward-backward-delete-char ()
quoted-insert (C-q or C-v)
tab-insert (M-TAB)
self-insert (a, b, A, 1, !, ...)
bracketed-paste-begin ()
self-insert instead of
executing any editing commands.
Bracketed paste sets the region (the characters between point and the mark) to the inserted text. It uses the concept of an active mark: when the mark is active, Readline redisplay uses the terminal's standout mode to denote the region.
transpose-chars (C-t)
transpose-words (M-t)
upcase-word (M-u)
downcase-word (M-l)
capitalize-word (M-c)
overwrite-mode ()
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.
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kill-line (C-k)
backward-kill-line (C-x Rubout)
unix-line-discard (C-u)
kill-whole-line ()
kill-word (M-d)
forward-word.
backward-kill-word (M-DEL)
backward-word.
shell-transpose-words (M-C-t)
shell-forward-word and
shell-backward-word.
unix-word-rubout (C-w)
unix-filename-rubout ()
delete-horizontal-space ()
kill-region ()
copy-region-as-kill ()
copy-backward-word ()
backward-word.
By default, this command is unbound.
copy-forward-word ()
forward-word.
By default, this command is unbound.
yank (C-y)
yank-pop (M-y)
yank or yank-pop.
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digit-argument (M-0, M-1, ... M--)
universal-argument ()
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 nor 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.
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complete (TAB)
possible-completions (M-?)
completion-display-width, the value of
the environment variable COLUMNS, or the screen width, in that order.
insert-completions (M-*)
possible-completions.
menu-complete ()
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.
menu-complete-backward ()
menu-complete, but moves backward through the list
of possible completions, as if menu-complete had been given a
negative argument.
delete-char-or-list ()
delete-char).
If at the end of the line, behaves identically to
possible-completions.
This command is unbound by default.
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start-kbd-macro (C-x ()
end-kbd-macro (C-x ))
call-last-kbd-macro (C-x e)
print-last-kbd-macro ()
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re-read-init-file (C-x C-r)
abort (C-g)
bell-style).
do-lowercase-version (M-A, M-B, M-x, ...)
prefix-meta (ESC)
undo (C-_ or C-x C-u)
revert-line (M-r)
undo
command enough times to get back to the beginning.
tilde-expand (M-~)
set-mark (C-@)
exchange-point-and-mark (C-x C-x)
character-search (C-])
character-search-backward (M-C-])
skip-csi-sequence ()
insert-comment (M-#)
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 ()
dump-variables ()
dump-macros ()
emacs-editing-mode (C-e)
vi command mode, this causes a switch to emacs
editing mode.
vi-editing-mode (M-C-j)
emacs editing mode, this causes a switch to vi
editing mode.
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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 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--2020 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.
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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.
2.1 Basic Behavior Using the default behavior of Readline. 2.2 Custom Functions Adding your own functions to Readline. 2.3 Readline Variables Variables accessible to custom functions. 2.4 Readline Convenience Functions Functions which Readline supplies to aid in writing your own custom functions. 2.5 Readline Signal Handling How Readline behaves when it receives signals. 2.6 Custom Completers Supplanting or supplementing Readline's completion functions.
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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
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So, one might say
|
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.
Readline performs some expansion on the prompt before it is
displayed on the screen. See the description of rl_expand_prompt
(see section 2.4.6 Redisplay) for additional details, especially if prompt
will contain characters that do not consume physical screen space when
displayed.
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.
|
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);
}
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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().
|
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:
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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 (see section 2.6 Custom Completers).
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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.
2.2.1 Readline Typedefs C declarations to make code readable. 2.2.2 Writing a New Function Variables and calling conventions.
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For readability, 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 **);
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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
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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 value greater than zero if some error occurs. This is the convention obeyed by all of the builtin Readline bindable command functions.
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These variables are available to function writers.
rl_extend_line_buffer is available to increase
the memory allocated to rl_line_buffer.
rl_line_buffer
(the point).
rl_line_buffer. When
rl_point is at the end of the line, rl_point and
rl_end are equal.
readline() causes
Readline to return after accepting that many characters, rather
than reading up to a character bound to accept-line.
readline(), and should not be assigned to directly.
The rl_set_prompt() function (see section 2.4.6 Redisplay) may
be used to modify the prompt string after calling readline().
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.
rl_readline_version would have the
value 0x0402.
TERM environment variable
the first time it is called.
NULL, Readline defaults to stdin.
NULL, Readline defaults to stdout.
LINES and
COLUMNS environment variables greater precedence than values fetched
from the kernel when computing the screen dimensions.
readline prints the first prompt.
readline
starts reading input characters.
rl_getc, the default Readline character input function
(see section 2.4.8 Character Input).
In general, an application that sets rl_getc_function should consider
setting rl_input_available_hook as well.
rl_instream; if an application is using a
different input source, it should set the hook appropriately.
Readline queries for available input when implementing intra-key-sequence
timeouts during input and incremental searches.
This may use an application-specific timeout before returning a value;
Readline uses the value passed to rl_set_keyboard_input_timeout()
or the value of the user-settable keyseq-timeout variable.
This is designed for use by applications using Readline's callback interface
(see section 2.4.12 Alternate Interface), which may not use the traditional
read(2) and file descriptor interface, or other applications using
a different input mechanism.
If an application uses an input mechanism or hook that can potentially exceed
the value of keyseq-timeout, it should increase the timeout or set
this hook appropriately even when not using the callback interface.
In general, an application that sets rl_getc_function should consider
setting rl_input_available_hook as well.
rl_redisplay, the default Readline
redisplay function (see section 2.4.6 Redisplay).
int flag that says whether or not to use eight-bit characters.
By default, this is set to rl_prep_terminal
(see section 2.4.9 Terminal Management).
rl_prep_term_function.
By default, this is set to rl_deprep_terminal
(see section 2.4.9 Terminal Management).
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
RL_STATE_INITIALIZING
RL_STATE_INITIALIZED
RL_STATE_TERMPREPPED
RL_STATE_READCMD
RL_STATE_METANEXT
RL_STATE_DISPATCHING
RL_STATE_MOREINPUT
RL_STATE_ISEARCH
RL_STATE_NSEARCH
RL_STATE_SEARCH
RL_STATE_NUMERICARG
RL_STATE_MACROINPUT
RL_STATE_MACRODEF
RL_STATE_OVERWRITE
RL_STATE_COMPLETING
RL_STATE_SIGHANDLER
RL_STATE_UNDOING
RL_STATE_INPUTPENDING
rl_execute_next().
RL_STATE_TTYCSAVED
RL_STATE_CALLBACK
RL_STATE_VIMOTION
RL_STATE_MULTIKEY
RL_STATE_VICMDONCE
readline().
RL_STATE_DONE
accept-line
and is about to return the line to the caller.
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2.4.1 Naming a Function How to give a function you write a name. 2.4.2 Selecting a Keymap Making keymaps. 2.4.3 Binding Keys Changing Keymaps. 2.4.4 Associating Function Names and Bindings Translate function names to key sequences. 2.4.5 Allowing Undoing How to make your functions undoable. 2.4.6 Redisplay Functions to control line display. 2.4.7 Modifying Text Functions to modify rl_line_buffer.2.4.8 Character Input Functions to read keyboard input. 2.4.9 Terminal Management Functions to manage terminal settings. 2.4.10 Utility Functions Generally useful functions and hooks. 2.4.11 Miscellaneous Functions Functions that don't fall into any category. 2.4.12 Alternate Interface Using Readline in a `callback' fashion. 2.4.13 A Readline Example An example Readline function. 2.4.14 Alternate Interface Example An example program using the alternate interface.
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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:
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.
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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.
malloc(); the caller should free it by calling
rl_free_keymap() when done.
rl_discard_keymap to free subordindate keymaps and macros.
Readline has several internal keymaps. These functions allow you to change which keymap is active.
set keymap inputrc line (see section 1.3 Readline Init File).
set keymap inputrc line (see section 1.3 Readline Init File).
set keymap inputrc directive
see section 1.3 Readline Init File).
The name may not be one of Readline's builtin keymap names;
you may not add a different name for one of Readline's builtin keymaps.
You may replace the name associated with a given keymap by calling this
function more than once with the same keymap argument.
You may associate a registered name with a new keymap by calling this
function more than once with the same name argument.
There is no way to remove a named keymap once the name has been
registered.
Readline will make a copy of name.
The return value is greater than zero unless name is one of
Readline's builtin keymap names or keymap is one of Readline's
builtin keymaps.
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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
(see section 2.3 Readline Variables).
These functions manage key bindings.
rl_bind_keyseq_in_map.
ISFUNC), a macro
(ISMACR), or a keymap (ISKMAP). This makes new keymaps as
necessary. The initial keymap in which to do bindings is map.
inputrc file and
perform any key bindings and variable assignments found
(see section 1.3 Readline Init File).
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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.
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).
It takes a "translated" key sequence and should not be used if the key sequence
can include NUL.
rl_function_of_keyseq with the
addition of the len parameter.
It takes a "translated" key sequence and should be used if the key sequence
can include NUL.
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.
rl_outstream.
free or
rl_free when you are done.
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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().
rl_insert_text() and
rl_delete_text(), but could be the result of calls to
rl_add_undo().
rl_begin_undo_group
(). There should be one call to rl_end_undo_group()
for each call to rl_begin_undo_group().
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.
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rl_line_buffer.
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.
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.
rl_save_prompt before the last call to rl_message,
call rl_restore_prompt before calling this function.
rl_message().
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.
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.
rl_expand_prompt() to expand the prompt and sets rl_prompt
to the result.
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rl_insert_text() instead.
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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.
rl_read_key(). Up to 512 characters may be pushed back.
rl_stuff_char returns 1 if the character was successfully inserted;
0 otherwise.
rl_read_key()
is called. This sets rl_pending_input.
rl_execute_next(). This works only if the
pending input has not already been read with rl_read_key().
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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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.
rl_prep_terminal(), leaving the terminal in
the state in which it was before the most recent call to
rl_prep_terminal().
stty) to their Readline equivalents.
The bindings are performed in kmap.
rl_tty_set_default_bindings so
that the terminal editing characters are bound to rl_insert.
The bindings are performed in kmap.
vt100).
If terminal_name is NULL, the value of the TERM
environment variable is used.
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rl_save_state.
The contents of the readline_state structure are documented
in `readline.h'.
The caller is responsible for freeing the structure.
malloc.
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.
rl_line_buffer has enough space to hold len
characters, possibly reallocating it if necessary.
readline() calls it before
reading any input.
bell-style.
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 (see section 1.3.1 Readline Init File Syntax).
When displaying completions, this function sets the number of columns used
for display to the value of completion-display-width, the value of
the environment variable COLUMNS, or the screen width, in that order.
The following are implemented as macros, defined in chardefs.h.
Applications should refrain from using them.
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rl_generic_bind() instead.
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.
inputrc
file (see section 1.3.1 Readline Init File Syntax).
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.
blink-matching-paren has been enabled.
clear_history() function.
This differs from clear_history because it frees private data
Readline saves in the history list.
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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 accommodate this need, readline can
also be invoked as a `callback' function from an event loop. There
are functions available to make this easy.
readline(), the handler function should free the
line when it it finished with it.
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 installed 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,
and the line handler remains installed,
the terminal settings are modified for Readline's use again.
EOF is indicated by calling lhandler with a
NULL line.
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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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);
}
|
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Here is a complete program that illustrates Readline's alternate interface. It reads lines from the terminal and displays them, providing the standard history and TAB completion functions. It understands the EOF character or "exit" to exit the program.
/* Standard include files. stdio.h is required. */
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <locale.h>
/* Used for select(2) */
#include <sys/types.h>
#include <sys/select.h>
#include <signal.h>
#include <stdio.h>
/* Standard readline include files. */
#include <readline/readline.h>
#include <readline/history.h>
static void cb_linehandler (char *);
static void sighandler (int);
int running;
int sigwinch_received;
const char *prompt = "rltest$ ";
/* Handle SIGWINCH and window size changes when readline is not active and
reading a character. */
static void
sighandler (int sig)
{
sigwinch_received = 1;
}
/* Callback function called for each line when accept-line executed, EOF
seen, or EOF character read. This sets a flag and returns; it could
also call exit(3). */
static void
cb_linehandler (char *line)
{
/* Can use ^D (stty eof) or `exit' to exit. */
if (line == NULL || strcmp (line, "exit") == 0)
{
if (line == 0)
printf ("\n");
printf ("exit\n");
/* This function needs to be called to reset the terminal settings,
and calling it from the line handler keeps one extra prompt from
being displayed. */
rl_callback_handler_remove ();
running = 0;
}
else
{
if (*line)
add_history (line);
printf ("input line: %s\n", line);
free (line);
}
}
int
main (int c, char **v)
{
fd_set fds;
int r;
/* Set the default locale values according to environment variables. */
setlocale (LC_ALL, "");
/* Handle window size changes when readline is not active and reading
characters. */
signal (SIGWINCH, sighandler);
/* Install the line handler. */
rl_callback_handler_install (prompt, cb_linehandler);
/* Enter a simple event loop. This waits until something is available
to read on readline's input stream (defaults to standard input) and
calls the builtin character read callback to read it. It does not
have to modify the user's terminal settings. */
running = 1;
while (running)
{
FD_ZERO (&fds);
FD_SET (fileno (rl_instream), &fds);
r = select (FD_SETSIZE, &fds, NULL, NULL, NULL);
if (r < 0 && errno != EINTR)
{
perror ("rltest: select");
rl_callback_handler_remove ();
break;
}
if (sigwinch_received)
{
rl_resize_terminal ();
sigwinch_received = 0;
}
if (r < 0)
continue;
if (FD_ISSET (fileno (rl_instream), &fds))
rl_callback_read_char ();
}
printf ("rltest: Event loop has exited\n");
return 0;
}
|
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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,
SIGHUP,
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.
When an application is using the callback interface
(see section 2.4.12 Alternate Interface), Readline installs signal handlers only for
the duration of the call to rl_callback_read_char. Applications
using the callback interface should be prepared to clean up Readline's
state if they wish to handle the signal before the line handler completes
and restores the terminal state.
If an application using the callback interface wishes to have Readline
install its signal handlers at the time the application calls
rl_callback_handler_install and remove them only when a complete
line of input has been read, it should set the
rl_persistent_signal_handlers variable to a non-zero value.
This allows an application to defer all of the handling of the signals
Readline catches to Readline.
Applications should use this variable with care; it can result in Readline
catching signals and not acting on them (or allowing the application to react
to them) until the application calls rl_callback_read_char. This
can result in an application becoming less responsive to keyboard signals
like SIGINT.
If an application does not want or need to perform any signal handling, or
does not need to do any processing between calls to rl_callback_read_char,
setting this variable may be desirable.
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.
SIGINT, SIGQUIT, SIGTERM, SIGHUP, SIGALRM,
SIGTSTP, SIGTTIN, and SIGTTOU.
The default value of rl_catch_signals is 1.
SIGWINCH.
The default value of rl_catch_sigwinch is 1.
rl_callback_read_char that constitutes an entire single line,
it should set this variable to a non-zero value.
The default value of rl_persistent_signal_handlers is 0.
SIGWINCH, Readline will modify the
LINES and COLUMNS environment variables upon receipt of a
SIGWINCH
The default value of rl_change_environment 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.
readline() was called, and remove the Readline signal handlers for
all signals, depending on the values of rl_catch_signals and
rl_catch_sigwinch.
rl_cleanup_after_signal(). The
Readline signal handler for SIGINT calls this to abort the
current input line.
rl_catch_signals and
rl_catch_sigwinch.
If an application wants to force Readline to handle any signals that
have arrived while it has been executing, rl_check_signals()
will call Readline's internal signal handler if there are any pending
signals. This is primarily intended for those applications that use
a custom rl_getc_function (see section 2.3 Readline Variables) and wish
to handle signals received while waiting for input.
rl_pending_signal() can be used independently
to determine whether or not there are any pending signals.
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 it receives
a SIGWINCH.
SIGINT, SIGQUIT, or
SIGTSTP will display the character generating that signal.
If an application does not want to install a SIGWINCH handler, but
is still interested in the screen dimensions, it may query Readline's idea
of the screen size.
The following functions install and remove Readline's signal handlers.
SIGINT, SIGQUIT,
SIGTERM, SIGHUP, SIGALRM, SIGTSTP, SIGTTIN,
SIGTTOU, and SIGWINCH, depending on the values of
rl_catch_signals and rl_catch_sigwinch.
rl_set_signals().
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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.
2.6.1 How Completing Works The logic used to do completion. 2.6.2 Completion Functions Functions provided by Readline. 2.6.3 Completion Variables Variables which control completion. 2.6.4 A Short Completion Example An example of writing completer subroutines.
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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:
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.
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.
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.
rl_completion_matches()). The default is to do filename completion.
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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Here is the complete list of callable completion functions present in Readline.
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.
rl_complete
(). This calls rl_complete_internal() with an argument of
`?'.
rl_complete().
This calls rl_complete_internal() with an argument of `*'.
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().
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.
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rl_completion_matches().
NULL means to use rl_filename_completion_function(),
the default filename completer.
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.
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.
rl_completer_word_break_characters should be
used to break words for the completer.
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.
opendir().
The directory completion hook returns an integer that should be non-zero if the function modifies its directory argument. The function should not modify the directory argument if it returns 0.
rl_directory_completion_hook,
it only modifies the directory name used in opendir, not what is
displayed when the possible completions are printed or inserted. It is
called before rl_directory_completion_hook.
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().
The directory rewrite hook returns an integer that should be non-zero if the function modifies its directory argument. The function should not modify the directory argument if it returns 0.
stat() to determine the file's type and characteristics.
This function does not need to remove quote characters from the filename.
The stat hook returns an integer that should be non-zero if the function modifies its directory argument. The function should not modify the directory argument if it returns 0.
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.
You may call that function from this hook.
" \t\n\"\\'`@$><=;|&{(".
rl_complete_internal(). The default list is the value of
rl_basic_word_break_characters.
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.
rl_completer_word_break_characters are treated as any other character,
unless they also appear within this list.
rl_filename_quote_characters and
rl_filename_quoting_desired is set to a non-zero value.
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.
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.
rl_ignore_completion_duplicates, will attempt to remove duplicate
matches.
rl_complete_internal()
(see section 2.6.2 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().
rl_complete_internal(). This is
set to the appropriate value before any application-specific completion
function is called.
self-insert.
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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. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <sys/types.h>
#ifdef HAVE_SYS_FILE_H
# include <sys/file.h>
#endif
#include <sys/stat.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#if defined (HAVE_STRING_H)
# include <string.h>
#else /* !HAVE_STRING_H */
# include <strings.h>
#endif /* !HAVE_STRING_H */
#ifdef HAVE_STDLIB_H
# include <stdlib.h>
#endif
#include <time.h>
#include <readline/readline.h>
#include <readline/history.h>
extern char *xmalloc PARAMS((size_t));
/* The names of functions that actually do the manipulation. */
int com_list PARAMS((char *));
int com_view PARAMS((char *));
int com_rename PARAMS((char *));
int com_stat PARAMS((char *));
int com_pwd PARAMS((char *));
int com_delete PARAMS((char *));
int com_help PARAMS((char *));
int com_cd PARAMS((char *));
int com_quit PARAMS((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 global means the user is done using this program. */
int done;
char *
dupstr (s)
char *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 PARAMS((const char *, int));
char **fileman_completion PARAMS((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. Return the 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;
#if defined (__MSDOS__)
/* more.com doesn't grok slashes in pathnames */
sprintf (syscom, "less %s", arg);
#else
sprintf (syscom, "more %s", arg);
#endif
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'. Possibilities 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. Write it yourself.\n",
caller);
}
/* Return non-zero if ARG is a valid argument for CALLER, else print
an error message and return zero. */
int
valid_argument (caller, arg)
char *caller, *arg;
{
if (!arg || !*arg)
{
fprintf (stderr, "%s: Argument required.\n", caller);
return (0);
}
return (1);
}
|
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Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. http://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. |
The purpose of this License is to make a manual, textbook, or other 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 author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.
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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 1.3 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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| Jump to: | A C E I K N R V Y |
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| Jump to: | A C E I K N R V Y |
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| [ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
| Jump to: | _
A B C D E F H I K M N O P Q R S T U V Y |
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A B C D E F H I K M N O P Q R S T U V Y |
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| [Top] | [Contents] | [Index] | [ ? ] |
| [Top] | [Contents] | [Index] | [ ? ] |
1. Command Line Editing
2. Programming with GNU Readline
A. GNU Free Documentation License
Concept Index
Function and Variable Index
| [Top] | [Contents] | [Index] | [ ? ] |
| Button | Name | Go to | From 1.2.3 go to |
|---|---|---|---|
| [ < ] | Back | previous section in reading order | 1.2.2 |
| [ > ] | Forward | next section in reading order | 1.2.4 |
| [ << ] | FastBack | previous or up-and-previous section | 1.1 |
| [ Up ] | Up | up section | 1.2 |
| [ >> ] | FastForward | next or up-and-next section | 1.3 |
| [Top] | Top | cover (top) of document | |
| [Contents] | Contents | table of contents | |
| [Index] | Index | concept index | |
| [ ? ] | About | this page |