GNU Readline Library

This document describes the GNU Readline Library, a utility which aids in the consistency of user interface across discrete programs that need to provide a command line interface.

Published by the Free Software Foundation
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Copyright (C) 1989, 1991 Free Software Foundation, Inc.

Command Line Editing

This chapter describes the basic features of the GNU command line editing interface.

Introduction to Line Editing

The following paragraphs describe the notation used to represent keystrokes.

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

The text M-k is read as `Meta-K' and describes the character produced when the meta key (if you have one) is depressed, and the k key is pressed. If you do not have a meta key, the identical keystroke can be generated by typing ESC first, and then typing k. Either process is known as metafying the k key.

The text M-C-k is read as `Meta-Control-k' and describes the character produced by metafying C-k.

In addition, several keys have their own names. Specifically, DEL, ESC, LFD, SPC, RET, and TAB all stand for themselves when seen in this text, or in an init file (@xref{Readline Init File}).

Readline Interaction

Often during an interactive session you type in a long line of text, only to notice that the first word on the line is misspelled. The Readline library gives you a set of commands for manipulating the text as you type it in, allowing you to just fix your typo, and not forcing you to retype the majority of the line. Using these editing commands, you move the cursor to the place that needs correction, and delete or insert the text of the corrections. Then, when you are satisfied with the line, you simply press RETURN. You do not have to be at the end of the line to press RETURN; the entire line is accepted regardless of the location of the cursor within the line.

Readline Init File Syntax

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

Variable Settings
You can change the state of a few variables in Readline by using the set command within the init file. Here is how you would specify that you wish to use vi line editing commands:
set editing-mode vi
Right now, there are only a few variables which can be set; so few, in fact, that we just list them here:
Controls what happens when Readline wants to ring the terminal bell. If set to `none', Readline never rings the bell. If set to `visible', Readline uses a visible bell if one is available. If set to `audible' (the default), Readline attempts to ring the terminal's bell.
The string to insert at the beginning of the line when the insert-comment command is executed. The default value is "#".
The number of possible completions that determines when the user is asked whether he wants to see the list of possibilities. If the number of possible completions is greater than this value, Readline will ask the user whether or not he wishes to view them; otherwise, they are simply listed. The default limit is 100.
If set to `on', Readline will convert characters with the eigth bit set to an ASCII key sequence by stripping the eigth bit and prepending an ESC character, converting them to a meta-prefixed key sequence. The default value is `on'.
If set to `On', readline will inhibit word completion. Completion characters will be inserted into the line as if they had been mapped to self-insert. The default is `off'.
The editing-mode variable controls which editing mode you are using. 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'.
When set to `on', readline will try to enable the application keypad when it is called. Some systems need this to enable the arrow keys. The default is `off'.
If set to `on', tilde expansion is performed when Readline attempts word completion. The default is `off'.
This variable can be set to either `on' or `off'. Setting it to `on' means that the text of the lines that you edit will scroll horizontally on a single screen line when they are longer than the width of the screen, instead of wrapping onto a new screen line. By default, this variable is set to `off'.
Sets Readline's idea of the current keymap for key binding commands. Acceptable keymap names are emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, vi-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.
If set to `on', completed directory names have a slash appended. The default is `on'.
This variable, when set to `on', says to display an asterisk (`*') at the start of history lines which have been modified. This variable is `off' by default.
If set to `on', Readline will enable eight-bit input (it will not strip the eighth bit from the characters it reads), regardless of what the terminal claims it can support. The default value is `off'. The name meta-flag is a synonym for this variable.
If set to `on', Readline will display characters with the eighth bit set directly rather than as a meta-prefixed escape sequence. The default is `off'.
This alters the default behavior of the completion functions. If set to `on', words which have more than one possible completion cause the matches to be listed immediately instead of ringing the bell. The default value is `off'.
If set to `on', a character denoting a file's type is appended to the filename when listing possible completions. The default is `off'.
Key Bindings
The syntax for controlling key bindings in the init file is simple. First you have to know the name of the command that you want to change. The following pages contain tables of the command name, the default keybinding, and a short description of what the command does. Once you know the name of the command, simply place the name of the key you wish to bind the command to, a colon, and then the name of the command on a line in the init file. The name of the key can be expressed in different ways, depending on which is most comfortable for you.
keyname: function-name or macro
keyname is the name of a key spelled out in English. For example:
Control-u: universal-argument
Meta-Rubout: backward-kill-word
Control-o: "> output"
In the above example, `C-u' is bound to the function universal-argument, and `C-o' is bound to run the macro expressed on the right hand side (that is, to insert the text `> output' into the line).
"keyseq": function-name or macro
keyseq differs from keyname above in that strings denoting an entire key sequence can be specified, by placing the key sequence in double quotes. Some GNU Emacs style key escapes can be used, as in the following example, but the special character names are not recognized.
"\C-u": universal-argument
"\C-x\C-r": re-read-init-file
"\e[11~": "Function Key 1"
In the above example, `C-u' is 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 escape sequences are available when specifying key sequences:
control prefix
meta prefix
an escape character
When entering the text of a macro, single or double quotes should be used to indicate a macro definition. Unquoted text is assumed to be a function name. Backslash will quote any character in the macro text, including `"' and `''. For example, the following binding will make `C-x \' insert a single `\' into the line:
"\C-x\\": "\\"

Conditional Init Constructs

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

The $if construct allows bindings to be made based on the editing mode, the terminal being used, or the application using Readline. The text of the test extends to the end of the line; no characters are required to isolate it.
The mode= form of the $if directive is used to test whether Readline is in emacs or vi mode. This may be used in conjunction with the `set keymap' command, for instance, to set bindings in the emacs-standard and emacs-ctlx keymaps only if Readline is starting out in emacs mode.
The term= form may be used to include terminal-specific key bindings, perhaps to bind the key sequences output by the terminal's function keys. The word on the right side of the `=' is tested against 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.
The application construct is used to include application-specific settings. Each program using the Readline library sets the application name, and you can test for it. This could be used to bind key sequences to functions useful for a specific program. For instance, the following command adds a key sequence that quotes the current or previous word in Bash:
$if Bash
# Quote the current or previous word
"\C-xq": "\eb\"\ef\""
This command, as you saw in the previous example, terminates an $if command.
Commands in this branch of the $if directive are executed if the test fails.

Sample Init File

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

# This file controls the behaviour of line input editing for
# programs that use the Gnu Readline library.  Existing programs
# include FTP, Bash, and Gdb.
# You can re-read the inputrc file with C-x C-r.
# Lines beginning with '#' are comments.
# 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


# 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="

# 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

Bindable Readline Commands

This section describes Readline commands that may be bound to key sequences.

Commands For Moving

beginning-of-line (C-a)
Move to the start of the current line.
end-of-line (C-e)
Move to the end of the line.
forward-char (C-f)
Move forward a character.
backward-char (C-b)
Move back a character.
forward-word (M-f)
Move forward to the end of the next word. Words are composed of letters and digits.
backward-word (M-b)
Move back to the start of this, or the previous, word. Words are composed of letters and digits.
clear-screen (C-l)
Clear the screen and redraw the current line, leaving the current line at the top of the screen.
redraw-current-line ()
Refresh the current line. By default, this is unbound.

Commands For Manipulating The History

accept-line (Newline, Return)
Accept the line regardless of where the cursor is. If this line is non-empty, add it to the history list. If this line was a history line, then restore the history line to its original state.
previous-history (C-p)
Move `up' through the history list.
next-history (C-n)
Move `down' through the history list.
beginning-of-history (M-<)
Move to the first line in the history.
end-of-history (M->)
Move to the end of the input history, i.e., the line you are entering.
reverse-search-history (C-r)
Search backward starting at the current line and moving `up' through the history as necessary. This is an incremental search.
forward-search-history (C-s)
Search forward starting at the current line and moving `down' through the the history as necessary. This is an incremental search.
non-incremental-reverse-search-history (M-p)
Search backward starting at the current line and moving `up' through the history as necessary using a non-incremental search for a string supplied by the user.
non-incremental-forward-search-history (M-n)
Search forward starting at the current line and moving `down' through the the history as necessary using a non-incremental search for a string supplied by the user.
history-search-forward ()
Search forward through the history for the string of characters between the start of the current line and the current cursor position (the `point'). This is a non-incremental search. By default, this command is unbound.
history-search-backward ()
Search backward through the history for the string of characters between the start of the current line and the point. This is a non-incremental search. By default, this command is unbound.
yank-nth-arg (M-C-y)
Insert the first argument to the previous command (usually the second word on the previous line). With an argument n, insert the nth word from the previous command (the words in the previous command begin with word 0). A negative argument inserts the nth word from the end of the previous command.
yank-last-arg (M-., M-_)
Insert last argument to the previous command (the last word of the previous history entry). With an argument, behave exactly like yank-nth-arg.

Commands For Changing Text

delete-char (C-d)
Delete the character under the cursor. If the cursor is at the beginning of the line, there are no characters in the line, and the last character typed was not C-d, then return EOF.
backward-delete-char (Rubout)
Delete the character behind the cursor. A numeric arg says to kill the characters instead of deleting them.
quoted-insert (C-q, C-v)
Add the next character that you type to the line verbatim. This is how to insert key sequences like C-q, for example.
tab-insert (M-TAB)
Insert a tab character.
self-insert (a, b, A, 1, !, ...)
Insert yourself.
transpose-chars (C-t)
Drag the character before the cursor forward over the character at the cursor, moving the cursor forward as well. If the insertion point is at the end of the line, then this transposes the last two characters of the line. Negative argumentss don't work.
transpose-words (M-t)
Drag the word behind the cursor past the word in front of the cursor moving the cursor over that word as well.
upcase-word (M-u)
Uppercase the current (or following) word. With a negative argument, do the previous word, but do not move the cursor.
downcase-word (M-l)
Lowercase the current (or following) word. With a negative argument, do the previous word, but do not move the cursor.
capitalize-word (M-c)
Capitalize the current (or following) word. With a negative argument, do the previous word, but do not move the cursor.

Killing And Yanking

kill-line (C-k)
Kill the text from the current cursor position to the end of the line.
backward-kill-line (C-x Rubout)
Kill backward to the beginning of the line.
unix-line-discard (C-u)
Kill backward from the cursor to the beginning of the current line. Save the killed text on the kill-ring.
kill-whole-line ()
Kill all characters on the current line, no matter where the cursor is. By default, this is unbound.
kill-word (M-d)
Kill from the cursor to the end of the current word, or if between words, to the end of the next word. Word boundaries are the same as forward-word.
backward-kill-word (M-DEL)
Kill the word behind the cursor. Word boundaries are the same as backward-word.
unix-word-rubout (C-w)
Kill the word behind the cursor, using white space as a word boundary. The killed text is saved on the kill-ring.
delete-horizontal-space ()
Delete all spaces and tabs around point. By default, this is unbound.
kill-region ()
Kill the text between the point and the mark (saved cursor position. This text is referred to as the region. By default, this command is unbound.
copy-region-as-kill ()
Copy the text in the region to the kill buffer, so you can yank it right away. By default, this command is unbound.
copy-backward-word ()
Copy the word before point to the kill buffer. By default, this command is unbound.
copy-forward-word ()
Copy the word following point to the kill buffer. By default, this command is unbound.
yank (C-y)
Yank the top of the kill ring into the buffer at the current cursor position.
yank-pop (M-y)
Rotate the kill-ring, and yank the new top. You can only do this if the prior command is yank or yank-pop.

Specifying Numeric Arguments

digit-argument (M-0, M-1, ... M--)
Add this digit to the argument already accumulating, or start a new argument. M-- starts a negative argument.
universal-argument ()
Each time this is executed, the argument count is multiplied by four. The argument count is initially one, so executing this function the first time makes the argument count four. By default, this is not bound to a key.

Letting Readline Type For You

complete (TAB)
Attempt to do completion on the text before the cursor. This is application-specific. Generally, if you are typing a filename argument, you can do filename completion; if you are typing a command, you can do command completion, if you are typing in a symbol to GDB, you can do symbol name completion, if you are typing in a variable to Bash, you can do variable name completion, and so on.
possible-completions (M-?)
List the possible completions of the text before the cursor.
insert-completions (M-*)
Insert all completions of the text before point that would have been generated by possible-completions.

Keyboard Macros

start-kbd-macro (C-x ()
Begin saving the characters typed into the current keyboard macro.
end-kbd-macro (C-x ))
Stop saving the characters typed into the current keyboard macro and save the definition.
call-last-kbd-macro (C-x e)
Re-execute the last keyboard macro defined, by making the characters in the macro appear as if typed at the keyboard.

Some Miscellaneous Commands

re-read-init-file (C-x C-r)
Read in the contents of the inputrc file, and incorporate any bindings or variable assignments found there.
abort (C-g)
Abort the current editing command and ring the terminal's bell (subject to the setting of bell-style).
do-uppercase-version (M-a, M-b, M-x, ...)
If the metafied character x is lowercase, run the command that is bound to the corresponding uppercase character.
prefix-meta (ESC)
Make the next character that you type be metafied. This is for people without a meta key. Typing `ESC f' is equivalent to typing `M-f'.
undo (C-_, C-x C-u)
Incremental undo, separately remembered for each line.
revert-line (M-r)
Undo all changes made to this line. This is like typing the undo command enough times to get back to the beginning.
tilde-expand (M-~)
Perform tilde expansion on the current word.
set-mark (C-@)
Set the mark to the current point. If a numeric argument is supplied, the mark is set to that position.
exchange-point-and-mark (C-x C-x)
Swap the point with the mark. The current cursor position is set to the saved position, and the old cursor position is saved as the mark.
character-search (C-])
A character is read and point is moved to the next occurrence of that character. A negative count searches for previous occurrences.
character-search-backward (M-C-])
A character is read and point is moved to the previous occurrence of that character. A negative count searches for subsequent occurrences.
insert-comment (M-#)
The value of the 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 ()
Print all of the functions and their key bindings to the readline output stream. If a numeric argument is supplied, the output is formatted in such a way that it can be made part of an inputrc file. This command is unbound by default.
dump-variables ()
Print all of the settable variables and their values to the readline output stream. If a numeric argument is supplied, the output is formatted in such a way that it can be made part of an inputrc file. This command is unbound by default.
dump-macros ()
Print all of the readline key sequences bound to macros and the strings they ouput. If a numeric argument is supplied, the output is formatted in such a way that it can be made part of an inputrc file. This command is unbound by default.

Readline vi Mode

While the Readline library does not have a full set of vi editing functions, it does contain enough to allow simple editing of the line. The Readline vi mode behaves as specified in the POSIX 1003.2 standard.

In order to switch interactively between emacs and vi editing modes, use the command M-C-j (toggle-editing-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.

Programming with GNU Readline

This chapter describes the interface between the GNU Readline Library and other programs. If you are a programmer, and you wish to include the features found in GNU Readline such as completion, line editing, and interactive history manipulation in your own programs, this section is for you.

Basic Behavior

Many programs provide a command line interface, such as mail, ftp, and sh. For such programs, the default behaviour of Readline is sufficient. This section describes how to use Readline in the simplest way possible, perhaps to replace calls in your code to gets() or fgets ().

The function readline () prints a prompt and then reads and returns a single line of text from the user. The line readline returns is allocated with malloc (); you should free () the line when you are done with it. The declaration for readline in ANSI C is

char *readline (char *prompt);

So, one might say

char *line = readline ("Enter a line: ");

in order to read a line of text from the user. The line 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, int (*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).

Custom Functions

Readline provides many functions for manipulating the text of the line, but it isn't possible to anticipate the needs of all programs. This section describes the various functions and variables defined within the Readline library which allow a user program to add customized functionality to Readline.

The Function Type

For readabilty, we declare a new type of object, called Function. A Function is a C function which returns an int. The type declaration for Function is:

typedef int Function ();

The reason for declaring this new type is to make it easier to write code describing pointers to C functions. Let us say we had a variable called func which was a pointer to a function. Instead of the classic C declaration

int (*)()func;

we may write

Function *func;

Similarly, there are

typedef void VFunction ();
typedef char *CPFunction (); and
typedef char **CPPFunction ();

for functions returning no value, pointer to char, and pointer to pointer to char, respectively.

Writing a New Function

In order to write new functions for Readline, you need to know the calling conventions for keyboard-invoked functions, and the names of the variables that describe the current state of the line read so far.

The calling sequence for a command foo looks like

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.

Readline Variables

These variables are available to function writers.

Variable: char * rl_line_buffer

This is the line gathered so far. You are welcome to modify the contents of the line, but see section Allowing Undoing.

Variable: int rl_point

The offset of the current cursor position in rl_line_buffer (the point).

Variable: int rl_end

The number of characters present in rl_line_buffer. When rl_point is at the end of the line, rl_point and rl_end are equal.

Variable: int rl_mark

The mark (saved position) in the current line. If set, the mark and point define a region.

Variable: int rl_done

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

Variable: int rl_pending_input

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

Variable: char * rl_prompt

The prompt Readline uses. This is set from the argument to readline (), and should not be assigned to directly.

Variable: char * rl_library_version

The version number of this revision of the library.

Variable: char * rl_terminal_name

The terminal type, used for initialization.

Variable: char * rl_readline_name

This variable is set to a unique name by each application using Readline. The value allows conditional parsing of the inputrc file (see section Conditional Init Constructs).

Variable: FILE * rl_instream

The stdio stream from which Readline reads input.

Variable: FILE * rl_outstream

The stdio stream to which Readline performs output.

Variable: Function * rl_startup_hook

If non-zero, this is the address of a function to call just before readline prints the first prompt.

Variable: Function * rl_event_hook

If non-zero, this is the address of a function to call periodically when readline is waiting for terminal input.

Variable: Function * rl_getc_function

If non-zero, readline will call indirectly through this pointer to get a character from the input stream. By default, it is set to rl_getc, the default readline character input function (see section Utility Functions).

Variable: Function * rl_redisplay_function

If non-zero, readline will call indirectly through this pointer to update the display with the current contents of the editing buffer. By default, it is set to rl_redisplay, the default readline redisplay function (see section Redisplay).

Variable: Keymap rl_executing_keymap

This variable is set to the keymap (see section Selecting a Keymap) in which the currently executing readline function was found.

Variable: Keymap rl_binding_keymap

This variable is set to the keymap (see section Selecting a Keymap) in which the last key binding occurred.

Readline Convenience Functions

Naming a Function

The user can dynamically change the bindings of keys while using Readline. This is done by representing the function with a descriptive name. The user is able to type the descriptive name when referring to the function. Thus, in an init file, one might find

Meta-Rubout:	backward-kill-word

This binds the keystroke Meta-Rubout to the function descriptively named backward-kill-word. You, as the programmer, should bind the functions you write to descriptive names as well. Readline provides a function for doing that:

Function: int rl_add_defun (char *name, Function *function, int key)

Add name to the list of named functions. Make function be the function that gets called. If key is not -1, then bind it to function using rl_bind_key ().

Using this function alone is sufficient for most applications. It is the recommended way to add a few functions to the default functions that Readline has built in. If you need to do something other than adding a function to Readline, you may need to use the underlying functions described below.

Selecting a Keymap

Key bindings take place on a keymap. The keymap is the association between the keys that the user types and the functions that get run. You can make your own keymaps, copy existing keymaps, and tell Readline which keymap to use.

Function: Keymap rl_make_bare_keymap ()

Returns a new, empty keymap. The space for the keymap is allocated with malloc (); you should free () it when you are done.

Function: Keymap rl_copy_keymap (Keymap map)

Return a new keymap which is a copy of map.

Function: Keymap rl_make_keymap ()

Return a new keymap with the printing characters bound to rl_insert, the lowercase Meta characters bound to run their equivalents, and the Meta digits bound to produce numeric arguments.

Function: void rl_discard_keymap (Keymap keymap)

Free the storage associated with keymap.

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

Function: Keymap rl_get_keymap ()

Returns the currently active keymap.

Function: void rl_set_keymap (Keymap keymap)

Makes keymap the currently active keymap.

Function: Keymap rl_get_keymap_by_name (char *name)

Return the keymap matching name. name is one which would be supplied in a set keymap inputrc line (@xref{Readline Init File}).

Binding Keys

You associate keys 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.

These functions manage key bindings.

Function: int rl_bind_key (int key, Function *function)

Binds key to function in the currently active keymap. Returns non-zero in the case of an invalid key.

Function: int rl_bind_key_in_map (int key, Function *function, Keymap map)

Bind key to function in map. Returns non-zero in the case of an invalid key.

Function: int rl_unbind_key (int key)

Bind key to the null function in the currently active keymap. Returns non-zero in case of error.

Function: int rl_unbind_key_in_map (int key, Keymap map)

Bind key to the null function in map. Returns non-zero in case of error.

Function: int rl_generic_bind (int type, char *keyseq, char *data, Keymap map)

Bind the key sequence represented by the string keyseq to the arbitrary pointer data. type says what kind of data is pointed to by data; this can be a function (ISFUNC), a macro (ISMACR), or a keymap (ISKMAP). This makes new keymaps as necessary. The initial keymap in which to do bindings is map.

Function: int rl_parse_and_bind (char *line)

Parse line as if it had been read from the inputrc file and perform any key bindings and variable assignments found (@xref{Readline Init File}).

Function: int rl_read_init_file (char *filename)

Read keybindings and variable assignments from filename (@xref{Readline Init File}).

Associating Function Names and Bindings

These functions allow you to find out what keys invoke named functions and the functions invoked by a particular key sequence.

Function: Function * rl_named_function (char *name)

Return the function with name name.

Function: Function * rl_function_of_keyseq (char *keyseq, Keymap map, int *type)

Return the function invoked by keyseq in keymap map. If map is NULL, the current keymap is used. If type is not NULL, the type of the object is returned in it (one of ISFUNC, ISKMAP, or ISMACR).

Function: char ** rl_invoking_keyseqs (Function *function)

Return an array of strings representing the key sequences used to invoke function in the current keymap.

Function: char ** rl_invoking_keyseqs_in_map (Function *function, Keymap map)

Return an array of strings representing the key sequences used to invoke function in the keymap map.

Function: void rl_function_dumper (int readable)

Print the readline function names and the key sequences currently bound to them to rl_outstream. If readable is non-zero, the list is formatted in such a way that it can be made part of an inputrc file and re-read.

Function: void rl_list_funmap_names ()

Print the names of all bindable Readline functions to rl_outstream.

Allowing Undoing

Supporting the undo command is a painless thing, and makes your functions much more useful. It is certainly easy to try something if you know you can undo it. I could use an undo function for the stock market.

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:


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

Function: int rl_begin_undo_group ()

Begins saving undo information in a group construct. The undo information usually comes from calls to rl_insert_text () and rl_delete_text (), but could be the result of calls to rl_add_undo ().

Function: int rl_end_undo_group ()

Closes the current undo group started with rl_begin_undo_group (). There should be one call to rl_end_undo_group () for each call to rl_begin_undo_group ().

Function: void rl_add_undo (enum undo_code what, int start, int end, char *text)

Remember how to undo an event (according to what). The affected text runs from start to end, and encompasses text.

Function: void free_undo_list ()

Free the existing undo list.

Function: int rl_do_undo ()

Undo the first thing on the undo list. Returns 0 if there was nothing to undo, non-zero if something was undone.

Finally, if you neither insert nor delete text, but directly modify the existing text (e.g., change its case), call rl_modifying () once, just before you modify the text. You must supply the indices of the text range that you are going to modify.

Function: int rl_modifying (int start, int end)

Tell Readline to save the text between start and end as a single undo unit. It is assumed that you will subsequently modify that text.


Function: int rl_redisplay ()

Change what's displayed on the screen to reflect the current contents of rl_line_buffer.

Function: int rl_forced_update_display ()

Force the line to be updated and redisplayed, whether or not Readline thinks the screen display is correct.

Function: int rl_on_new_line ()

Tell the update routines that we have moved onto a new (empty) line, usually after ouputting a newline.

Function: int rl_reset_line_state ()

Reset the display state to a clean state and redisplay the current line starting on a new line.

Function: int rl_message (va_alist)

The arguments are a string as would be supplied to printf. The resulting string is displayed in the echo area. The echo area is also used to display numeric arguments and search strings.

Function: int rl_clear_message ()

Clear the message in the echo area.

Modifying Text

Function: int rl_insert_text (char *text)

Insert text into the line at the current cursor position.

Function: int rl_delete_text (int start, int end)

Delete the text between start and end in the current line.

Function: char * rl_copy_text (int start, int end)

Return a copy of the text between start and end in the current line.

Function: int rl_kill_text (int start, int end)

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

Utility Functions

Function: int rl_read_key ()

Return the next character available. This handles input inserted into the input stream via pending input (see section Readline Variables) and rl_stuff_char (), macros, and characters read from the keyboard.

Function: int rl_getc (FILE *)

Return the next character available from the keyboard.

Function: int rl_stuff_char (int c)

Insert c into the Readline input stream. It will be "read" before Readline attempts to read characters from the terminal with rl_read_key ().

Function: int rl_initialize ()

Initialize or re-initialize Readline's internal state.

Function: int rl_reset_terminal (char *terminal_name)

Reinitialize Readline's idea of the terminal settings using terminal_name as the terminal type (e.g., vt100).

Function: int alphabetic (int c)

Return 1 if c is an alphabetic character.

Function: int numeric (int c)

Return 1 if c is a numeric character.

Function: int ding ()

Ring the terminal bell, obeying the setting of bell-style.

The following are implemented as macros, defined in chartypes.h.

Function: int uppercase_p (int c)

Return 1 if c is an uppercase alphabetic character.

Function: int lowercase_p (int c)

Return 1 if c is a lowercase alphabetic character.

Function: int digit_p (int c)

Return 1 if c is a numeric character.

Function: int to_upper (int c)

If c is a lowercase alphabetic character, return the corresponding uppercase character.

Function: int to_lower (int c)

If c is an uppercase alphabetic character, return the corresponding lowercase character.

Function: int digit_value (int c)

If c is a number, return the value it represents.

Alternate Interface

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

Function: void rl_callback_handler_install (char *prompt, Vfunction *lhandler)

Set up the terminal for readline I/O and display the initial expanded value of prompt. Save the value of lhandler to use as a callback when a complete line of input has been entered.

Function: void rl_callback_read_char ()

Whenever an application determines that keyboard input is available, it should call rl_callback_read_char(), which will read the next character from the current input source. If that character completes the line, rl_callback_read_char will invoke the lhandler function saved by rl_callback_handler_install to process the line. EOF is indicated by calling lhandler with a NULL line.

Function: void rl_callback_handler_remove ()

Restore the terminal to its initial state and remove the line handler. This may be called from within a callback as well as independently.

An Example

Here is a function which changes lowercase characters to their uppercase equivalents, and uppercase characters to lowercase. If this function was bound to `M-c', then typing `M-c' would change the case of the character under point. Typing `M-1 0 M-c' would change the case of the following 10 characters, leaving the cursor on the last character changed.

/* Invert the case of the COUNT following characters. */
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;
    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 (uppercase_p (rl_line_buffer[i]))
        rl_line_buffer[i] = to_lower (rl_line_buffer[i]);
      else if (lowercase_p (rl_line_buffer[i]))
        rl_line_buffer[i] = 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);

Custom Completers

Typically, a program that reads commands from the user has a way of disambiguating commands and data. If your program is one of these, then it can provide completion for commands, data, or both. The following sections describe how your program and Readline cooperate to provide this service.

How Completing Works

In order to complete some text, the full list of possible completions must be available. That is, it is not possible to accurately expand a partial word without knowing all of the possible words which make sense in that context. The Readline library provides the user interface to completion, and two of the most common completion functions: filename and username. For completing other types of text, you must write your own completion function. This section describes exactly what such functions must do, and provides an example.

There are three major functions used to perform completion:

  1. The user-interface function rl_complete (). This function is called with the same arguments as other Readline functions intended for interactive use: count and invoking_key. It isolates the word to be completed and calls completion_matches () to generate a list of possible completions. It then either lists the possible completions, inserts the possible completions, or actually performs the completion, depending on which behavior is desired.
  2. The internal function completion_matches () uses your generator function to generate the list of possible matches, and then returns the array of these matches. You should place the address of your generator function in rl_completion_entry_function.
  3. The generator function is called repeatedly from completion_matches (), returning a string each time. The arguments to the generator function are text and state. text is the partial word to be completed. state is zero the first time the function is called, allowing the generator to perform any necessary initialization, and a positive non-zero integer for each subsequent call. When the generator function returns (char *)NULL this signals completion_matches () that there are no more possibilities left. 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.

Function: int rl_complete (int ignore, int invoking_key)

Complete the word at or before point. You have supplied the function that does the initial simple matching selection algorithm (see completion_matches ()). The default is to do filename completion.

Variable: Function * rl_completion_entry_function

This is a pointer to the generator function for completion_matches (). If the value of rl_completion_entry_function is (Function *)NULL then the default filename generator function, filename_entry_function (), is used.

Completion Functions

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

Function: int rl_complete_internal (int what_to_do)

Complete the word at or before point. what_to_do says what to do with the completion. A value of `?' means list the possible completions. `TAB' means do standard completion. `*' means insert all of the possible completions. `!' means to display all of the possible completions, if there is more than one, as well as performing partial completion.

Function: int rl_complete (int ignore, int invoking_key)

Complete the word at or before point. You have supplied the function that does the initial simple matching selection algorithm (see completion_matches () and rl_completion_entry_function). The default is to do filename completion. This calls rl_complete_internal () with an argument depending on invoking_key.

Function: int rl_possible_completions (int count, int invoking_key))

List the possible completions. See description of rl_complete (). This calls rl_complete_internal () with an argument of `?'.

Function: int rl_insert_completions (int count, int invoking_key))

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

Function: char ** completion_matches (char *text, CPFunction *entry_func)

Returns an array of (char *) which is a list of completions for text. If there are no completions, returns (char **)NULL. The first entry in the returned array is the substitution for text. The remaining entries are the possible completions. The array is terminated with a NULL pointer.

entry_func is a function of two args, and returns a (char *). The first argument is text. The second is a state argument; it is zero on the first call, and non-zero on subsequent calls. entry_func returns a NULL pointer to the caller when there are no more matches.

Function: char * filename_completion_function (char *text, int state)

A generator function for filename completion in the general case. Note that completion in Bash is a little different because of all the pathnames that must be followed when looking up completions for a command. The Bash source is a useful reference for writing custom completion functions.

Function: char * username_completion_function (char *text, int state)

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

Completion Variables

Variable: Function * rl_completion_entry_function

A pointer to the generator function for completion_matches (). NULL means to use filename_entry_function (), the default filename completer.

Variable: CPPFunction * rl_attempted_completion_function

A pointer to an alternative function to create matches. The function is called with text, start, and end. start and end are indices in rl_line_buffer saying what the boundaries of text are. If this function exists and returns NULL, 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.

Variable: CPFunction * rl_filename_quoting_function

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

Variable: CPFunction * rl_filename_dequoting_function

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

Variable: Function * rl_char_is_quoted_p

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

Variable: int rl_completion_query_items

Up to this many items will be displayed in response to a possible-completions call. After that, we ask the user if she is sure she wants to see them all. The default value is 100.

Variable: char * rl_basic_word_break_characters

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

Variable: char * rl_basic_quote_characters

List of quote characters which can cause a word break.

Variable: char * rl_completer_word_break_characters

The list of characters that signal a break between words for rl_complete_internal (). The default list is the value of rl_basic_word_break_characters.

Variable: char * rl_completer_quote_characters

List of characters which can be used to quote a substring of the line. Completion occurs on the entire substring, and within the substring rl_completer_word_break_characters are treated as any other character, unless they also appear within this list.

Variable: char * rl_filename_quote_characters

A list of characters that cause a filename to be quoted by the completer when they appear in a completed filename. The default is empty.

Variable: char * rl_special_prefixes

The list of characters that are word break characters, but should be left in text when it is passed to the completion function. Programs can use this to help determine what kind of completing to do. For instance, Bash sets this variable to "$@" so that it can complete shell variables and hostnames.

Variable: int rl_completion_append_character

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

Variable: int rl_ignore_completion_duplicates

If non-zero, then disallow duplicates in the matches. Default is 1.

Variable: int rl_filename_completion_desired

Non-zero means that the results of the matches are to be treated as filenames. This is always zero on entry, and can only be changed within a completion entry generator function. If it is set to a non-zero value, directory names have a slash appended and Readline attempts to quote completed filenames if they contain any embedded word break characters.

Variable: int rl_filename_quoting_desired

Non-zero means that the results of the matches are to be quoted using double quotes (or an application-specific quoting mechanism) if the completed filename contains any characters in rl_filename_quote_chars. This is always non-zero 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.

Variable: int rl_inhibit_completion

If this variable is non-zero, completion is inhibited. The completion character will be inserted as any other bound to self-insert.

Variable: Function * rl_ignore_some_completions_function

This function, if defined, is called by the completer when real filename completion is done, after all the matching names have been generated. It is passed a NULL terminated array of matches. The first element (matches[0]) is the maximal substring common to all matches. This function can re-arrange the list of matches as required, but each element deleted from the array must be freed.

Variable: Function * rl_directory_completion_hook

This function, if defined, is allowed to modify the directory portion of filenames Readline completes. It is called with the address of a string (the current directory name) as an argument. It could be used to expand symbolic links or shell variables in pathnames.

A Short Completion Example

Here is a small application demonstrating the use of the GNU Readline library. It is called fileman, and the source code resides in `examples/fileman.c'. This sample application provides completion of command names, line editing features, and access to the history list.

/* fileman.c -- A tiny application which demonstrates how to use the
   GNU Readline library.  This application interactively allows users
   to manipulate files and their modes. */

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

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

extern char *getwd ();
extern char *xmalloc ();

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

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

typedef struct {
  char *name;			/* User printable name of the function. */
  Function *func;		/* Function to call to do the job. */
  char *doc;			/* Documentation for this function.  */

COMMAND commands[] = {
  { "cd", com_cd, "Change to directory DIR" },
  { "delete", com_delete, "Delete FILE" },
  { "help", com_help, "Display this text" },
  { "?", com_help, "Synonym for `help'" },
  { "list", com_list, "List files in DIR" },
  { "ls", com_list, "Synonym for `list'" },
  { "pwd", com_pwd, "Print the current working directory" },
  { "quit", com_quit, "Quit using Fileman" },
  { "rename", com_rename, "Rename FILE to NEWNAME" },
  { "stat", com_stat, "Print out statistics on FILE" },
  { "view", com_view, "View the contents of FILE" },
  { (char *)NULL, (Function *)NULL, (char *)NULL }

/* 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)
     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)

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

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

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

  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. */
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 = '\0';

  return s;

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

char *command_generator ();
char **fileman_completion ();

/* Tell the GNU Readline library how to complete.  We want to try to complete
   on command names if this is the first word in the line, or on filenames
   if not. */
initialize_readline ()
  /* Allow conditional parsing of the ~/.inputrc file. */
  rl_readline_name = "FileMan";

  /* Tell the completer that we want a crack first. */
  rl_attempted_completion_function = (CPPFunction *)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)
     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 = completion_matches (text, command_generator);

  return (matches);

/* Generator function for command completion.  STATE lets us know whether
   to start from scratch; without any state (i.e. STATE == 0), then we
   start at the top of the list. */
char *
command_generator (text, state)
     char *text;
     int state;
  static int list_index, len;
  char *name;

  /* If this is a new word to complete, initialize now.  This includes
     saving the length of TEXT for efficiency, and initializing the index
     variable to 0. */
  if (!state)
      list_index = 0;
      len = strlen (text);

  /* Return the next name which partially matches from the command list. */
  while (name = commands[list_index].name)

      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 == 1) ? "" : "s",
          (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);

  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);

      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 = getwd (dir);
  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",

/* Return non-zero if ARG is a valid argument for CALLER, else print
   an error message and return zero. */
valid_argument (caller, arg)
     char *caller, *arg;
  if (!arg || !*arg)
      fprintf (stderr, "%s: Argument required.\n", caller);
      return (0);

  return (1);

Concept Index


  • interaction, readline
  • r

  • readline, function
  • Function and Variable Index


  • abort (C-g)
  • accept-line (Newline, Return)
  • alphabetic
  • b

  • backward-char (C-b)
  • backward-delete-char (Rubout)
  • backward-kill-line (C-x Rubout)
  • backward-kill-word (M-DEL)
  • backward-word (M-b)
  • beginning-of-history (M-&#60;)
  • beginning-of-line (C-a)
  • bell-style
  • c

  • call-last-kbd-macro (C-x e)
  • capitalize-word (M-c)
  • character-search (C-])
  • character-search-backward (M-C-])
  • clear-screen (C-l)
  • comment-begin
  • complete (TAB)
  • completion-query-items
  • completion_matches
  • convert-meta
  • copy-backward-word ()
  • copy-forward-word ()
  • copy-region-as-kill ()
  • d

  • delete-char (C-d)
  • delete-horizontal-space ()
  • digit-argument (M-0, M-1, ... M--)
  • digit_p
  • digit_value
  • ding
  • disable-completion
  • do-uppercase-version (M-a, M-b, M-x, ...)
  • downcase-word (M-l)
  • dump-functions ()
  • dump-macros ()
  • dump-variables ()
  • e

  • editing-mode
  • enable-keypad
  • end-kbd-macro (C-x ))
  • end-of-history (M-&#62;)
  • end-of-line (C-e)
  • exchange-point-and-mark (C-x C-x)
  • expand-tilde
  • f

  • filename_completion_function
  • forward-char (C-f)
  • forward-search-history (C-s)
  • forward-word (M-f)
  • free_undo_list
  • h

  • history-search-backward ()
  • history-search-forward ()
  • horizontal-scroll-mode
  • i

  • input-meta
  • insert-comment (M-#)
  • insert-completions (M-*)
  • k

  • keymap
  • kill-line (C-k)
  • kill-region ()
  • kill-whole-line ()
  • kill-word (M-d)
  • l

  • lowercase_p
  • m

  • mark-modified-lines
  • meta-flag
  • n

  • next-history (C-n)
  • non-incremental-forward-search-history (M-n)
  • non-incremental-reverse-search-history (M-p)
  • numeric
  • o

  • output-meta
  • p

  • possible-completions (M-?)
  • prefix-meta (ESC)
  • previous-history (C-p)
  • q

  • quoted-insert (C-q, C-v)
  • r

  • re-read-init-file (C-x C-r)
  • readline
  • redraw-current-line ()
  • reverse-search-history (C-r)
  • revert-line (M-r)
  • rl_add_defun
  • rl_add_undo
  • rl_attempted_completion_function
  • rl_basic_quote_characters
  • rl_basic_word_break_characters
  • rl_begin_undo_group
  • rl_bind_key
  • rl_bind_key_in_map
  • rl_binding_keymap
  • rl_callback_handler_install
  • rl_callback_handler_remove
  • rl_callback_read_char
  • rl_char_is_quoted_p
  • rl_clear_message
  • rl_complete
  • rl_complete_internal
  • rl_completer_quote_characters
  • rl_completer_word_break_characters
  • rl_completion_append_character
  • rl_completion_entry_function
  • rl_completion_query_items
  • rl_copy_keymap
  • rl_copy_text
  • rl_delete_text
  • rl_directory_completion_hook
  • rl_discard_keymap
  • rl_do_undo
  • rl_done
  • rl_end
  • rl_end_undo_group
  • rl_event_hook
  • rl_executing_keymap
  • rl_filename_completion_desired
  • rl_filename_dequoting_function
  • rl_filename_quote_characters
  • rl_filename_quoting_desired
  • rl_filename_quoting_function
  • rl_forced_update_display
  • rl_function_dumper
  • rl_function_of_keyseq
  • rl_generic_bind
  • rl_get_keymap
  • rl_get_keymap_by_name
  • rl_getc
  • rl_getc_function
  • rl_ignore_completion_duplicates
  • rl_ignore_some_completions_function
  • rl_inhibit_completion
  • rl_initialize
  • rl_insert_completions
  • rl_insert_text
  • rl_instream
  • rl_invoking_keyseqs
  • rl_invoking_keyseqs_in_map
  • rl_kill_text
  • rl_library_version
  • rl_line_buffer
  • rl_list_funmap_names
  • rl_make_bare_keymap
  • rl_make_keymap
  • rl_mark
  • rl_message
  • rl_modifying
  • rl_named_function
  • rl_on_new_line
  • rl_outstream
  • rl_parse_and_bind
  • rl_pending_input
  • rl_point
  • rl_possible_completions
  • rl_prompt
  • rl_read_init_file
  • rl_read_key
  • rl_readline_name
  • rl_redisplay
  • rl_redisplay_function
  • rl_reset_line_state
  • rl_reset_terminal
  • rl_set_keymap
  • rl_special_prefixes
  • rl_startup_hook
  • rl_stuff_char
  • rl_terminal_name
  • rl_unbind_key
  • rl_unbind_key_in_map
  • s

  • self-insert (a, b, A, 1, !, ...)
  • set-mark (C-@)
  • show-all-if-ambiguous
  • start-kbd-macro (C-x ()
  • t

  • tab-insert (M-TAB)
  • tilde-expand (M-~)
  • to_lower
  • to_upper
  • transpose-chars (C-t)
  • transpose-words (M-t)
  • u

  • undo (C-_, C-x C-u)
  • universal-argument ()
  • unix-line-discard (C-u)
  • unix-word-rubout (C-w)
  • upcase-word (M-u)
  • uppercase_p
  • username_completion_function
  • v

  • visible-stats
  • y

  • yank (C-y)
  • yank-last-arg (M-., M-_)
  • yank-nth-arg (M-C-y)
  • yank-pop (M-y)