editline —
command-line editing library with history
library “libeditline”
#include
<editline.h>
char *
readline(
const,
char,
*prompt);
void
add_history(
const,
char,
*line);
int
read_history(
const,
char,
*filename);
int
write_history(
const,
char,
*filename);
editline is a library that provides n
line-editing interface with history. It is intended to be functionally
equivalent with the
readline library
provided by the Free Software Foundation, but much smaller. The bulk of this
manual page describes the basic user interface. More APIs, both native and for
readline compatibility , are also
available. See the
editline.h header file
for details.
The
readline() function displays the given
prompt on stdout, waits for user input on
stdin and then returns a line of text with the trailing newline removed. The
data is returned in a buffer allocated with
malloc(3), so the
space should be released with
free(3) when the
calling program is done with it.
Each line returned is automatically saved in the internal history list, unless
it happens to be equal to the previous line. This is configurable if you are
building editline from source, i.e. if you would rather like to call
add_history() manually.
The
read_history() and
write_history() functions can be used to
load and store the history of your application.
Note: these APIs do not do any tilde or
environment variable expansion of the given filename.
A program that uses this library provides a simple emacs-like editing interface
to its users. A line may be edited before it is sent to the calling program by
typing either control characters or escape sequences. A control character,
shown as a caret followed by a letter, is typed by holding down the control
key while the letter is typed. For example,
^A is a control-A. An escape sequence is
entered by typing the escape key followed by one or more characters. The
escape key is abbreviated as
ESC. Note that
unlike control keys, case matters in escape sequences;
ESC F is not the same as
ESC f.
An editing command may be typed anywhere on the line, not just at the beginning.
In addition, a return may also be typed anywhere on the line, not just at the
end.
Most editing commands may be given a repeat count,
n, where
n
is a number. To enter a repeat count, type the escape key, the number, and
then the command to execute. For example,
ESC 4
^f moves forward four characters. If a command may be given a repeat
count then the text
[n] is given at the end
of its description.
The following control characters are accepted:
- ^A
- Move to the beginning of the line
- ^B
- Move left (backwards) [n]
- ^D
- Delete character [n]
- ^E
- Move to end of line
- ^F
- Move right (forwards) [n]
- ^G
- Ring the bell
- ^H
- Delete character before cursor (backspace key) [n]
- ^I
- Complete filename (tab key); see below
- ^J
- Done with line (return key)
- ^K
- Kill to end of line (or column [n])
- ^L
- Redisplay line
- ^M
- Done with line (alternate return key)
- ^N
- Get next line from history [n]
- ^P
- Get previous line from history [n]
- ^R
- Search backward (forward if [n]) through history for text; prefixing the
string with a caret (^) forces it to match only at the beginning of a
history line
- ^T
- Transpose characters
- ^V
- Insert next character, even if it is an edit command
- ^W
- Wipe to the mark
- ^X^X
- Exchange current location and mark
- ^Y
- Yank back last killed text
- ^[
- Start an escape sequence (escape key)
- ^]c
- Move forward to next character
c
- ^?
- Delete character before cursor (delete key) [n]
The following escape sequences are provided:
- ESC ^H
- Delete previous word (backspace key) [n]
- ESC DEL
- Delete previous word (delete key) [n]
- ESC SP
- Set the mark (space key); see ^X^X and ^Y above
- ESC .
- Get the last (or [n]'th) word from previous line
- ESC ?
- Show possible completions; see below
- ESC <
- Move to start of history
- ESC >
- Move to end of history
- ESC b
- Move backward a word [n]
- ESC d
- Delete word under cursor [n]
- ESC f
- Move forward a word [n]
- ESC l
- Make word lowercase [n]
- ESC m
- Toggle if 8bit chars display normally or with an
M- prefix
- ESC u
- Make word uppercase [n]
- ESC y
- Yank back last killed text
- ESC v
- Show library version
- ESC w
- Make area up to mark yankable
- ESC nn
- Set repeat count to the number nn
- ESC C
- Read from environment variable $C, where
C is an uppercase letter
The
editline library has a small macro
facility. If you type the escape key followed by an uppercase letter,
C, then the contents of the environment
variable
$C are read in as if you had typed
them at the keyboard. For example, if the variable
$L contains the following:
^A^Kecho
'^V^[[H^V^[[2J'^M
Then typing
ESC L will move to the beginning
of the line, kill the entire line, enter the echo command needed to clear the
terminal (if your terminal is like a VT-100), and send the line back to the
shell.
The
editline library also does filename
completion. Suppose the root directory has the following files in it:
bin vmunix
core vmunix.old
If you type
rm /v and then the tab key,
editline will then finish off as much of
the name as possible by adding
munix. Because
the name is not unique, it will then beep. If you type the escape key and a
question mark, it will display the two choices. If you then type a period and
a tab, the library will finish off the filename for you:
rm /v[TAB] munix .[TAB]
old
The tab key is shown by [TAB] and the automatically-entered text is shown in
italics, or underline.
To include
editline in your program, call it
as you do any other function and link your program with
-leditline.
The following brief example lets you enter a line and edit it, then displays it.
#include <stdio.h>
#include <stdlib.h>
#include <editline.h>
int main(void)
{
char *p;
while ((p = readline("CLI> "))) {
puts(p);
free(p);
}
return 0;
}
The original editline library was posted to comp.sources.unix newsgroup by
created by Simmule R. Turner and Rich Salz in 1992. It now exists in several
forks: Debian, Minix, Heimdal, Festival speech tools, Mozilla, Google Gadgets
for Linux, and many other places. The original manual page was made by David
W. Sanderson.
This version was originally based on the Minix 2 sources, but has since evolved
to include patches from all relevant forks. It is currently maintained by
Joachim Nilsson at GitHub,
⟨http://github.com/troglobit/editline⟩
Does not handle multiple lines or unicode characters well.