Readline Library Version 4.2.
This document describes the GNU Readline Library, a utility which aids in the consistency of user interface across discrete programs that need to provide a command line interface.
Published by the Free Software Foundation
59 Temple Place, Suite 330,
Boston, MA 02111 USA
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 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 Free Software Foundation.
Copyright (C) 1988-2001 Free Software Foundation, Inc.
This chapter describes the basic features of the GNU command line editing interface.
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 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.
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.
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.)
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.
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.
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.
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.
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.
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 @env{INPUTRC}. If that variable is unset, the default is `~/.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.
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 Conditional Init Constructs). Other lines denote variable settings and key bindings.
set command within the init file.
The syntax is simple:
set variable valueHere, for example, is how to change from the default Emacs-like key binding to use
vi line editing commands:
set editing-mode viVariable names and values, where appropriate, are recognized without regard to case. A great deal of run-time behavior is changeable with the following variables.
bell-style
comment-begin
insert-comment command is executed. The default value
is "#".
completion-ignore-case
completion-query-items
100.
convert-meta
disable-completion
self-insert. The default is `off'.
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'.
enable-keypad
expand-tilde
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; 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
mark-modified-lines
output-meta
print-completions-horizontally
show-all-if-ambiguous
visible-stats
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.
"\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'.
\C-
\M-
\e
\\
\"
\'
\a
\b
\d
\f
\n
\r
\t
\v
\nnn
\xnnn
"\C-x\\": "\\"
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 extends to the end of the line;
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.
application
$if Bash # Quote the current or previous word "\C-xq": "\eb\"\ef\"" $endif
$endif
$if command.
$else
$if directive are executed if
the test fails.
$include
$include /etc/inputrc
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
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.
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)
clear-screen (C-l)
redraw-current-line ()
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 ()
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 argument of each line in turn.
delete-char (C-d)
delete-char, then
return EOF.
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, !, ...)
transpose-chars (C-t)
transpose-words (M-t)
upcase-word (M-u)
downcase-word (M-l)
capitalize-word (M-c)
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.
unix-word-rubout (C-w)
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.
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 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.
complete (TAB)
possible-completions (M-?)
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.
delete-char-or-list ()
delete-char).
If at the end of the line, behaves identically to
possible-completions.
This command is unbound by default.
start-kbd-macro (C-x ()
end-kbd-macro (C-x ))
call-last-kbd-macro (C-x e)
re-read-init-file (C-x C-r)
abort (C-g)
bell-style).
do-uppercase-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-])
insert-comment (M-#)
comment-begin
variable is inserted at the beginning of the current line,
and the line is accepted as if a newline had been typed.
dump-functions ()
dump-variables ()
dump-macros ()
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 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.
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 (see section Custom Completers).
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.
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 **);
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
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.
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 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.
readline prints the first prompt.
readline
starts reading input characters.
rl_getc, the default Readline character input function
(see section Character Input).
rl_redisplay, the default Readline
redisplay function (see section Redisplay).
int flag that says whether or not to use eight-bit characters.
By default, this is set to rl_prep_terminal
(see section Terminal Management).
rl_prep_term_function.
By default, this is set to rl_deprep_terminal
(see section 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_DONE
accept-line
and is about to return the line to the caller.
rl_line_buffer.
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.
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_discard_keymap() when done.
Readline has several internal keymaps. These functions allow you to change which keymap is active.
set keymap inputrc line (see section Readline Init File).
set keymap inputrc line (see section Readline Init File).
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 Readline Variables).
These functions manage key bindings.
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 Readline Init File).
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).
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() the array when you are done, but not the pointers.
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.
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.
rl_message().
rl_save_prompt.
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.
rl_expand_prompt() to expand the prompt and sets rl_prompt
to the result.
rl_insert_text() instead.
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().
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. The default waiting period is
one-tenth of a second. Returns the old timeout value.
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.
vt100).
If terminal_name is NULL, the value of the TERM
environment variable is used.
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 Readline Init File Syntax).
The following are implemented as macros, defined in chardefs.h.
Applications should refrain from using them.
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 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.
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.
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. EOF is indicated by calling lhandler with a
NULL line.
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);
}
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.
SIGINT, SIGQUIT, SIGTERM, SIGALRM,
SIGTSTP, SIGTTIN, and SIGTTOU.
The default value of rl_catch_signals is 1.
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.
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 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.
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.
The following functions install and remove Readline's signal handlers.
SIGINT, SIGQUIT,
SIGTERM, SIGALRM, SIGTSTP, SIGTTIN,
SIGTTOU, and SIGWINCH, depending on the values of
rl_catch_signals and rl_catch_sigwinch.
rl_set_signals().
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.
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.
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.
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 `*'.
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.
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.
" \t\n\"\\'`@$><=;|&{(".
rl_complete_internal(). The default list is the value of
rl_basic_word_break_characters.
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
on entry, and can only be changed within a completion entry generator
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_complete_internal()
(see section Completion Functions) for the list of characters.
self-insert.
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.
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.
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. 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);
}
Jump to: c - e - i - k - n - r - v - y
Jump to: _ - a - b - c - d - e - f - h - i - k - m - n - o - p - q - r - s - t - u - v - y
This document was generated on 16 April 2001 using the texi2html translator version 1.52.