EDITLINE(3) | Library Functions Manual | EDITLINE(3) |
NAME
editline
—
command-line editing library with history
LIBRARY
library “libeditline”
SYNOPSIS
#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);
DESCRIPTION
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.
User Interface
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:
The tab key is shown by [TAB] and the automatically-entered text is shown in italics, or underline.
USAGE
To include editline
in your program, call
it as you do any other function and link your program with
-leditline.
Example
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; }
AUTHORS
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⟩
BUGS
Does not handle multiple lines or unicode characters well.
February 23, 2020 | Linux 6.7.4-arch1-1 |