Command-line editing library with history
char *
readline(prompt)
char *prompt;
void
add_history(line)
char *line;
Editline is a library that provides an line-editing interface with text recall. It is intended to be compatible with the readline library provided by the Free Software Foundation, but much smaller. The bulk of this manual page describes the user interface.
The readline routine 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. Before accepting input from the user, the specified prompt is displayed on the terminal.
The add_history routine makes a copy of the specified line and adds it to the internal history list.
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 ESC Show possible completions; see below 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 as themselves or with an ``M-'' prefix ESC u Make word uppercase [n] ESC y Yank back last killed text 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 followed by either a question mark or another escape, 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.
Cannot handle lines more than 80 columns.
Simmule R. Turner <uunet.uu.net!capitol!sysgo!simmy> and Rich $alz <[email protected]>. Original manual page by DaviD W. Sanderson <[email protected]>.