GETLINE(3) GETLINE(3)
NAME
getline - command-line editing library with history
SYNOPSIS
char *getline(char *prompt);
void gl_histadd(char *line);
void gl_setwidth(int width);
void gl_strwidth(int (*width_func)());
extern int (*gl_in_hook)(char *buf);
extern int (*gl_out_hook)(char *buf);
extern int (*gl_tab_hook)(char *buf, int prompt_width, int
*cursor_loc);
DESCRIPTION
The getline package is a set of library routines that implement an
editable command-line history.
Programming Interface
getline returns a pointer to a line of text read from the user,
prompting the user with the specified prompt. The pointer refers to a
static buffer allocated by the getline package. Clients may assume
that the pointer getline returns is always the same, and is never
NULL. The buffer getline returns to the caller contains the
terminating newline character, except on end of file, in which case
the first character in the buffer is 0 (NUL). File descriptors 0 and
1 must be connected to the terminal (not redirected), so the caller
should check for this condition (using isatty()) and call stdio
routines if the session is not interactive.
gl_histadd adds the given line to the getline history list if the line
is not empty and if it is different from the last line in the history
list (so the caller need not check for these conditions). gl_histadd
makes its own copies of all the lines it adds to the history list.
This is so the caller can reuse the buffer it supplies to gl_histadd.
gl_setwidth specifies the terminal width to use for horizontal
scrolling. The default value is 80 columns, and it is important to
properly specify the width or lines may wrap inadvertently.
gl_strwidth allows the application program to supply a prompt string
width calculation function that returns the number of screen positions
used by the argument string. By default strlen is used, but if the
prompt contains escape sequences the user can bind a function that
returns the actual number of screen postitions used by the argument
string, not including the escape characters.
In addition to the function call interface, getline has three
externally accessible function pointers that act as hooks if bound to
user-defined functions. getline supplies each of the functions with a
- 1 - Formatted: April 24, 2024
GETLINE(3) GETLINE(3)
pointer to the current buffer as the first argument, and expects the
return value to be the index of the first change the function made in
the buffer (or -1 if the function did not alter the buffer). After
the functions return, getline updates the screen as necessary. Note
that the functions may not alter the size of the buffer. Indeed, they
do not even know how large the buffer is!
getline calls gl_in_hook (initially NULL) each time it loads a new
buffer. More precisely, this is
+ at the first call to getline (with an empty buffer)
+ each time the user enters a new buffer from the history list
(with ^P or ^N)
+ when the user accepts an incremental search string (when the user
terminates the search).
getline calls gl_out_hook (initially NULL) when a line has been
completed by the user entering a NEWLINE (^J) or RETURN (^M). The
buffer gl_out_hook sees does not yet have the newline appended, and
gl_out_hook should not add a newline.
getline calls gl_tab_hook whenever the user types a TAB. In addition
to the buffer, getline supplies the current prompt_width (presumably
needed for tabbing calculations) and cursor_loc, a pointer to the
cursor location. (*cursor_loc = 0 corresponds to the first character
in the buffer) *cursor_loc tells gl_tab_hook where the TAB was typed.
Note that when it redraws the screen, getline will honor any change
gl_tab_hook may make to *cursor_loc. Note also that prompt_width may
not correspond to the actual width of prompt on the screen if prompt
contains escape sequences. gl_tab_hook is initially bound to the
getline internal static function gl_tab, which acts like a normal TAB
key by inserting spaces.
User Interface
To edit, the user moves the cursor to the point needing correction and
then inserts or deletes characters or words as needed. All the
editing commands are control characters, which typed by holding the
CTRL key down while typing another character. Control characters are
indicated below as the caret (^) followed by another character, such
as ^A.
All edit commands operate from any place on the line, not just at the
beginning.
These are the getline key bindings.
^A Move cursor to beginning of line.
^B Move cursor left (back) 1 column.
- 2 - Formatted: April 24, 2024
GETLINE(3) GETLINE(3)
ESC-B Move cursor back one word.
^D Delete the character under the cursor.
^E Move cursor to end of line.
^F Move cursor right (forward) 1 column.
ESC-F Move cursor forward one word.
^H Delete the character left of the cursor.@
^I Jump to next tab stop (may be redefined by the program).
^J Return the current line.
^K Kill from cursor to the end of the line (see ^Y).
^L Redisplay current line.
^M Return the current line.
^N Fetches next line from the history list.
^O Toggle overwrite/insert mode, initially in insert mode.
^P Fetches previous line from the history list.
^R Begin a reverse incremental search through history list.
Each printing character typed adds to the search substring
(initially empty), and getline finds and displays the
first matching location. Typing ^R again marks the
current starting location and begins a new search for the
current substring. Typing ^H or DEL deletes the last
character from the search string, and getline restarts the
search from the last starting location. Repeated ^H or
DEL characters therefore appear to unwind the search to
the match nearest the point where the user last typed ^R
or ^S. Typing ^H or DEL until the search string is empty
causes getline to reset the start of the search to the
beginning of the history list. Typing ESC or any other
editing character accepts the current match and terminates
the search.
^S Begin a forward incremental search through the history
list. The behavior is like that of ^R but in the opposite
direction through the history list.
^T Transpose current and previous character.
^U Kill the entire line (see ^Y).
^Y Yank previously killed text back at current location.
BACKSPACE Delete the character left of the cursor.
DEL Delete the character left of the cursor.
RETURN Return the current line.
TAB Jump to next tab stop (may be redefined by the program).
getline recognizes DOS and ANSI arrow keys. They cause the following
actions: up is the same as ^P, down is the same as ^N, left is the
same as ^P, and right is the same as ^F.
AUTHORS
Program by Christopher R. Thewalt (thewalt@ce.berkeley.edu)
Original man page by DaviD W. Sanderson (dws@cs.wisc.edu) and
Christopher R. Thewalt
- 3 - Formatted: April 24, 2024
GETLINE(3) GETLINE(3)
COPYRIGHT
(C) Copyright 1992,1993 by Christopher R. Thewalt and DaviD W.
Sanderson (but freely redistributable)
- 4 - Formatted: April 24, 2024
