Deprecated: Mac OS X < 10.3.x
NAME
ncurses - CRT screen handling and optimization package
SYNOPSIS
#include <curses.h>
DESCRIPTION
The ncurses library routines give the user a terminal-
independent method of updating character screens with rea-
sonable optimization. This implementation is ``new
curses'' (ncurses) and is the approved replacement for
4.4BSD classic curses, which has been discontinued.
The ncurses routines emulate the curses(3X) library of
System V Release 4 UNIX, and the XPG4 curses standard (XSI
curses) but the ncurses library is freely redistributable
in source form. Differences from the SVr4 curses are sum-
marized under the EXTENSIONS and BUGS sections below and
described in detail in the EXTENSIONS and BUGS sections of
individual man pages.
A program using these routines must be linked with the
-lncurses option, or (if it has been generated) with the
debugging library -lncurses_g. (Your system integrator
may also have installed these libraries under the names
-lcurses and -lcurses_g.) The ncurses_g library generates
trace logs (in a file called 'trace' in the current direc-
tory) that describe curses actions.
The ncurses package supports: overall screen, window and
pad manipulation; output to windows and pads; reading ter-
minal input; control over terminal and curses input and
output options; environment query routines; color manipu-
lation; use of soft label keys; terminfo capabilities; and
access to low-level terminal-manipulation routines.
To initialize the routines, the routine initscr or newterm
must be called before any of the other routines that deal
with windows and screens are used. The routine endwin
must be called before exiting. To get character-at-a-time
input without echoing (most interactive, screen oriented
programs want this), the following sequence should be
used:
initscr(); cbreak(); noecho();
Most programs would additionally use the sequence:
nonl();
intrflush(stdscr, FALSE);
keypad(stdscr, TRUE);
Before a curses program is run, the tab stops of the ter-
minal should be set and its initialization strings, if
defined, must be output. This can be done by executing
the tput init command after the shell environment variable
TERM has been exported. tset(1) is usually responsible
for doing this. [See terminfo(5) for further details.]
The ncurses library permits manipulation of data struc-
tures, called windows, which can be thought of as two-
dimensional arrays of characters representing all or part
of a CRT screen. A default window called stdscr, which is
the size of the terminal screen, is supplied. Others may
be created with newwin.
Note that curses does not handle overlapping windows,
that's done by the panel(3X) library. This means that you
can either use stdscr or divide the screen into tiled win-
dows and not using stdscr at all. Mixing the two will
result in unpredictable, and undesired, effects.
Windows are referred to by variables declared as WINDOW *.
These data structures are manipulated with routines
described here and elsewhere in the ncurses manual pages.
Among which the most basic routines are move and addch.
More general versions of these routines are included with
names beginning with w, allowing the user to specify a
window. The routines not beginning with w affect stdscr.)
After using routines to manipulate a window, refresh is
called, telling curses to make the user's CRT screen look
like stdscr. The characters in a window are actually of
type chtype, (character and attribute data) so that other
information about the character may also be stored with
each character.
Special windows called pads may also be manipulated.
These are windows which are not constrained to the size of
the screen and whose contents need not be completely dis-
played. See curs_pad(3X) for more information.
In addition to drawing characters on the screen, video
attributes and colors may be supported, causing the char-
acters to show up in such modes as underlined, in reverse
video, or in color on terminals that support such display
enhancements. Line drawing characters may be specified to
be output. On input, curses is also able to translate
arrow and function keys that transmit escape sequences
into single values. The video attributes, line drawing
characters, and input values use names, defined in
<curses.h>, such as A_REVERSE, ACS_HLINE, and KEY_LEFT.
If the environment variables LINES and COLUMNS are set, or
if the program is executing in a window environment, line
and column information in the environment will override
information read by terminfo. This would effect a program
running in an AT&T 630 layer, for example, where the size
of a screen is changeable (see ENVIRONMENT).
If the environment variable TERMINFO is defined, any pro-
gram using curses checks for a local terminal definition
before checking in the standard place. For example, if
TERM is set to att4424, then the compiled terminal defini-
tion is found in
/usr/share/terminfo/a/att4424.
(The a is copied from the first letter of att4424 to avoid
creation of huge directories.) However, if TERMINFO is
set to $HOME/myterms, curses first checks
$HOME/myterms/a/att4424,
and if that fails, it then checks
/usr/share/terminfo/a/att4424.
This is useful for developing experimental definitions or
when write permission in /usr/share/terminfo is not avail-
able.
The integer variables LINES and COLS are defined in
<curses.h> and will be filled in by initscr with the size
of the screen. The constants TRUE and FALSE have the val-
ues 1 and 0, respectively.
The curses routines also define the WINDOW * variable
curscr which is used for certain low-level operations like
clearing and redrawing a screen containing garbage. The
curscr can be used in only a few routines.
Routine and Argument Names
Many curses routines have two or more versions. The rou-
tines prefixed with w require a window argument. The rou-
tines prefixed with p require a pad argument. Those with-
out a prefix generally use stdscr.
The routines prefixed with mv require a y and x coordinate
to move to before performing the appropriate action. The
mv routines imply a call to move before the call to the
other routine. The coordinate y always refers to the row
(of the window), and x always refers to the column. The
upper left-hand corner is always (0,0), not (1,1).
The routines prefixed with mvw take both a window argument
and x and y coordinates. The window argument is always
specified before the coordinates.
In each case, win is the window affected, and pad is the
pad affected; win and pad are always pointers to type WIN-
DOW.
Option setting routines require a Boolean flag bf with the
value TRUE or FALSE; bf is always of type bool. The vari-
ables ch and attrs below are always of type chtype. The
types WINDOW, SCREEN, bool, and chtype are defined in
<curses.h>. The type TERMINAL is defined in <term.h>.
All other arguments are integers.
Routine Name Index
The following table lists each curses routine and the name
of the manual page on which it is described. Routines
flagged with `*' are ncurses-specific, not described by
XPG4 or present in SVr4.
RETURN VALUE
Routines that return an integer return ERR upon failure
and an integer value other than ERR upon successful com-
pletion, unless otherwise noted in the routine descrip-
tions.
All macros return the value of the w version, except
setscrreg, wsetscrreg, getyx, getbegyx, getmaxyx. The
return values of setscrreg, wsetscrreg, getyx, getbegyx,
and getmaxyx are undefined (i.e., these should not be used
as the right-hand side of assignment statements).
Routines that return pointers return NULL on error.
ENVIRONMENT
The following environment symbols are useful for customiz-
ing the runtime behavior of the ncurses library. The most
important ones have been already discussed in detail.
BAUDRATE
The debugging library checks this environment symbol
when the application has redirected output to a file.
The symbol's numeric value is used for the baudrate.
If no value is found ncurses uses 9600. This allows
testers to construct repeatable test-cases that take
into account costs that depend on baudrate.
CC When set, change occurrences of the command_character
(i.e., the cmdch capability) of the loaded terminfo
entries to the value of this symbol. Very few ter-
minfo entries provide this feature.
COLUMNS
Specify the width of the screen in characters.
Applications running in a windowing environment usu-
ally are able to obtain the width of the window in
which they are executing. If neither the $COLUMNS
value nor the terminal's screen size is available,
ncurses uses the size which may be specified in the
terminfo database (i.e., the cols capability).
It is important that your application use a correct
size for the screen. However, this is not always
possible because your application may be running on a
host which does not honor NAWS (Negotiations About
Window Size), or because you are temporarily running
as another user.
Either COLUMNS or LINES symbols may be specified
independently. This is mainly useful to circumvent
legacy misfeatures of terminal descriptions, e.g.,
xterm which commonly specifies a 65 line screen. For
best results, lines and cols should not be specified
in a terminal description for terminals which are run
as emulations.
Use the use_env function to disable this feature.
ESCDELAY
Specifies the total time, in milliseconds, for which
ncurses will await a character sequence, e.g., a
function key. The default value, 1000 milliseconds,
is enough for most uses. However, it is made a vari-
able to accommodate unusual applications.
The most common instance where you may wish to change
this value is to work with slow hosts, e.g., running
on a network. If the host cannot read characters
rapidly enough, it will have the same effect as if
the terminal did not send characters rapidly enough.
The library will still see a timeout.
Note that xterm mouse events are built up from char-
acter sequences received from the xterm. If your
application makes heavy use of multiple-clicking, you
may wish to lengthen this default value because the
timeout applies to the composed multi-click event as
well as the individual clicks.
HOME Tells ncurses where your home directory is. That is
where it may read and write auxiliary terminal
descriptions:
$HOME/.termcap
$HOME/.terminfo
LINES
Like COLUMNS, specify the height of the screen in
characters. See COLUMNS for a detailed description.
MOUSE_BUTTONS_123
This applies only to the OS/2 EMX port. It specifies
the order of buttons on the mouse. OS/2 numbers a
3-button mouse inconsistently from other platforms:
1 = left
2 = right
3 = middle.
This symbol lets you customize the mouse. The symbol
must be three numeric digits 1-3 in any order, e.g.,
123 or 321. If it is not specified, ncurses uses
132.
NCURSES_NO_PADDING
Most of the terminal descriptions in the terminfo
database are written for real "hardware" terminals.
Many people use terminal emulators which run in a
windowing environment and use curses-based applica-
tions. Terminal emulators can duplicate all of the
important aspects of a hardware terminal, but they do
not have the same limitations. The chief limitation
of a hardware terminal from the standpoint of your
application is the management of dataflow, i.e., tim-
ing. Unless a hardware terminal is interfaced into a
terminal concentrator (which does flow control), it
(or your application) must manage dataflow, prevent-
ing overruns. The cheapest solution (no hardware
cost) is for your program to do this by pausing after
operations that the terminal does slowly, such as
clearing the display.
As a result, many terminal descriptions (including
the vt100) have delay times embedded. You may wish
to use these descriptions, but not want to pay the
performance penalty.
Set the NCURSES_NO_PADDING symbol to disable all but
mandatory padding. Mandatory padding is used as a
part of special control sequences such as flash.
NCURSES_NO_SETBUF
Normally ncurses enables buffered output during ter-
minal initialization. This is done (as in SVr4
curses) for performance reasons. For testing pur-
poses, both of ncurses and certain applications, this
feature is made optional. Setting the
NCURSES_NO_SETBUF variable disables output buffering,
leaving the output in the original (usually line
buffered) mode.
NCURSES_TRACE
During initialization, the ncurses debugging library
checks the NCURSES_TRACE symbol. If it is defined,
to a numeric value, ncurses calls the trace function,
using that value as the argument.
The argument values, which are defined in curses.h,
provide several types of information. When running
with traces enabled, your application will write the
file trace to the current directory.
TERM Denotes your terminal type. Each terminal type is
distinct, though many are similar.
TERMCAP
If the ncurses library has been configured with term-
cap support, ncurses will check for a terminal's
description in termcap form if it is not available in
the terminfo database.
The TERMCAP symbol contains either a terminal
description (with newlines stripped out), or a file
name telling where the information denoted by the
TERM symbol exists. In either case, setting it
directs ncurses to ignore the usual place for this
information, e.g., /etc/termcap.
TERMINFO
Overrides the directory in which ncurses searches for
your terminal description. This is the simplest, but
not the only way to change the list of directories.
The complete list of directories in order follows:
- the last directory to which ncurses wrote, if any,
is searched first.
- the directory specified by the TERMINFO symbol
- $HOME/.terminfo
- directories listed in the TERMINFO_DIRS symbol
- one or more directories whose names are configured
and compiled into the ncurses library, e.g.,
/usr/share/terminfo
TERMINFO_DIRS
Specifies a list of directories to search for termi-
nal descriptions. The list is separated by colons
(i.e., ":") on Unix, semicolons on OS/2 EMX. All of
the terminal descriptions are in terminfo form, which
makes a subdirectory named for the first letter of
the terminal names therein.
TERMPATH
If TERMCAP does not hold a file name then ncurses
checks the TERMPATH symbol. This is a list of file-
names separated by spaces or colons (i.e., ":") on
Unix, semicolons on OS/2 EMX. If the TERMPATH symbol
is not set, ncurses looks in the files /etc/termcap,
/usr/share/misc/termcap and $HOME/.termcap, in that
order.
The library may be configured to disregard the following
variables when the current user is the superuser (root),
or if the application uses setuid or setgid permissions:
$TERMINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.
FILES
/usr/share/tabset
directory containing initialization files for the
terminal capability database /usr/share/terminfo ter-
minal capability database
SEE ALSO
terminfo(5) and related pages whose names begin "curs_"
for detailed routine descriptions.
EXTENSIONS
The ncurses library can be compiled with an option
(-DUSE_GETCAP) that falls back to the old-style /etc/term-
cap file if the terminal setup code cannot find a terminfo
entry corresponding to TERM. Use of this feature is not
recommended, as it essentially includes an entire termcap
compiler in the ncurses startup code, at significant cost
in core and startup cycles.
The ncurses library includes facilities for capturing
mouse events on certain terminals (including xterm). See
the curs_mouse(3X) manual page for details.
The ncurses library includes facilities for responding to
window resizing events, e.g., when running in an xterm.
See the resizeterm(3X) and wresize(3X) manual pages for
details. In addition, the library may be configured with
a SIGWINCH handler.
The ncurses library extends the fixed set of function key
capabilities of terminals by allowing the application
designer to define additional key sequences at runtime.
See the define_key(3X) and keyok(3X) manual pages for
details.
The ncurses library can exploit the capabilities of termi-
nals which implement the ISO-6429 SGR 39 and SGR 49 con-
trols, which allow an application to reset the terminal to
its original foreground and background colors. From the
users' perspective, the application is able to draw col-
ored text on a background whose color is set indepen-
dently, providing better control over color contrasts.
See the default_colors(3X) manual page for details.
The ncurses library includes a function for directing
application output to a printer attached to the terminal
device. See the curs_print(3X) manual page for details.
PORTABILITY
The ncurses library is intended to be BASE-level confor-
mant with the XSI Curses standard. Certain portions of
the EXTENDED XSI Curses functionality (including color
support) are supported. The following EXTENDED XSI Curses
calls in support of wide (multibyte) characters are not
yet implemented: add_wchnstr, add_wchstr, addnwstr, addw-
str, bkgrnd, bkgrndset, border_set, box_set, erasewchar,
get_wch, get_wstr, getbkgrnd, getn_wstr, getwchtype,
hline_set, in_wch, in_wchnstr, in_wchstr, innwstr,
ins_nwstr, ins_wch, ins_wstr, inwchnstr, inwchstr, inwstr,
key_name, killwchar, mvadd_wchnstr, mvadd_wchstr, mvaddnw-
str, mvaddwstr, mvget_wch, mvget_wstr, mvgetn_wstr, mvh-
line_set, mvin_wch, mvinnwstr, mvins_nwstr, mvins_wch,
mvins_wstr, mvinwchnstr, mvinwchstr, mvinwchstr, mvinwstr,
mvvline_set, mvwadd_wchnstr, mvwadd_wchstr, mvwaddnwstr,
mvwaddwstr, mvwget_ch, mvwget_wch, mvwget_wstr,
mvwgetn_wstr, mvwhline_set, mvwin_wch, mvwin_wchnstr,
mvwin_wchstr, mvwinnwstr, mvwins_nwstr, mvwins_wch,
mvwins_wstr, mvwinwchnstr. mvwinwstr, mvwvline_set,
pecho_wchar, slk_wset, term_attrs, unget_wch, vhline_set,
vid_attr, vid_puts, vline_set, wadd_wchnstr, wadd_wchstr,
waddnwstr, waddwstr, waddwstr, wbkgrnd, wbkgrndset,
wbkgrndset, wborder_set, wget_wch, wget_wstr, wgetbkgrnd,
wgetn_wstr, whline_set, win_wch, win_wchnstr, win_wchstr,
winnwstr, wins_nwstr, wins_wch, wins_wstr, winwchnstr,
winwchstr, winwstr, wunctrl, wvline_set,
A small number of local differences (that is, individual
differences between the XSI Curses and ncurses calls) are
described in PORTABILITY sections of the library man
pages.
The routine has_key is not part of XPG4, nor is it present
in SVr4. See the curs_getch(3X) manual page for details.
The routine slk_attr is not part of XPG4, nor is it pre-
sent in SVr4. See the curs_slk(3X) manual page for
details.
The routines getmouse, mousemask, ungetmouse, mouseinter-
val, and wenclose relating to mouse interfacing are not
part of XPG4, nor are they present in SVr4. See the
curs_mouse(3X) manual page for details.
The routine mcprint was not present in any previous curses
implementation. See the curs_print(3X) manual page for
details.
The routine wresize is not part of XPG4, nor is it present
in SVr4. See the wresize(3X) manual page for details.
In historic curses versions, delays embedded in the capa-
bilities cr, ind, cub1, ff and tab activated corresponding
delay bits in the UNIX tty driver. In this implementa-
tion, all padding is done by NUL sends. This method is
slightly more expensive, but narrows the interface to the
UNIX kernel significantly and increases the package's
portability correspondingly.
In the XSI standard and SVr4 manual pages, many entry
points have prototype arguments of the for char *const (or
cchar_t *const, or wchar_t *const, or void *const).
Depending on one's interpretation of the ANSI C standard
(see section 3.5.4.1), these declarations are either (a)
meaningless, or (b) meaningless and illegal. The declara-
tion const char *x is a modifiable pointer to unmodifiable
data, but char *const x' is an unmodifiable pointer to
modifiable data. Given that C passes arguments by value,
<type> *const as a formal type is at best dubious. Some
compilers choke on the prototypes. Therefore, in this
implementation, they have been changed to const <type> *
globally.
NOTES
The header file <curses.h> automatically includes the
header files <stdio.h> and <unctrl.h>.
If standard output from a ncurses program is re-directed
to something which is not a tty, screen updates will be
directed to standard error. This was an undocumented fea-
ture of AT&T System V Release 3 curses.
AUTHORS
Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey.
Based on pcurses by Pavel Curtis.
ncurses(3X)
www.fiveanddime.net