ncurses(3NCURSES) ncurses(3NCURSES)
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 reasonable optimization.
This implementation is “new curses” (ncurses) and is the approved re-
placement for 4.4BSD classic curses, which has been discontinued. This
describes ncurses version 6.4 (patch 20221231).
The ncurses library emulates the curses library of System V Release 4
UNIX, and XPG4 (X/Open Portability Guide) curses (also known as XSI
curses). XSI stands for X/Open System Interfaces Extension. The
ncurses library is freely redistributable in source form. Differences
from the SVr4 curses are summarized under the EXTENSIONS and PORTABIL-
ITY sections below and described in detail in the respective EXTEN-
SIONS, PORTABILITY and BUGS sections of individual man pages.
The ncurses library also provides many useful extensions, i.e., fea-
tures which cannot be implemented by a simple add-on library but which
require access to the internals of the library.
A program using these routines must be linked with the -lncurses op-
tion, or (if it has been generated) with the debugging library
-lncurses_g. (Your system integrator may also have installed these li-
braries under the names -lcurses and -lcurses_g.) The ncurses_g li-
brary generates trace logs (in a file called “trace” in the current di-
rectory) that describe curses actions. See also the section on ALTER-
NATE CONFIGURATIONS.
The ncurses package supports: overall screen, window and pad manipula-
tion; output to windows and pads; reading terminal input; control over
terminal and curses input and output options; environment query rou-
tines; color manipulation; use of soft label keys; terminfo capabili-
ties; and access to low-level terminal-manipulation routines.
Initialization
The library uses the locale which the calling program has initialized.
That is normally done with setlocale(3):
setlocale(LC_ALL, "");
If the locale is not initialized, the library assumes that characters
are printable as in ISO-8859-1, to work with certain legacy programs.
You should initialize the locale and not rely on specific details of
the library when the locale has not been setup.
The function initscr or newterm must be called to initialize the li-
brary before any of the other routines that deal with windows and
screens are used. The routine endwin(3X) must be called before exit-
ing.
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:
intrflush(stdscr, FALSE);
keypad(stdscr, TRUE);
Before a curses program is run, the tab stops of the terminal 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 environ-
ment variable TERM has been exported. tset(1) is usually responsible
for doing this. [See terminfo(5) for further details.]
Datatypes
The ncurses library permits manipulation of data structures, called
windows, which can be thought of as two-dimensional arrays of charac-
ters 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(3CURSES) library. This means that you can either use stdscr
or divide the screen into tiled windows 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 those, 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(3X) 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 at-
tribute 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 displayed. See pad(3NCURSES) for more informa-
tion.
In addition to drawing characters on the screen, video attributes and
colors may be supported, causing the characters 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 ar-
row and function keys that transmit escape sequences into single val-
ues. The video attributes, line drawing characters, and input values
use names, defined in <curses.h>, such as A_REVERSE, ACS_HLINE, and
KEY_LEFT.
Environment variables
If the environment variables LINES and COLUMNS are set, or if the pro-
gram is executing in a window environment, line and column information
in the environment will override information read by terminfo. This
would affect 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 program using
curses checks for a local terminal definition before checking in the
standard place. For example, if TERM is set to att4424, then the com-
piled terminal definition is found in
/etc/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
/etc/terminfo/a/att4424.
This is useful for developing experimental definitions or when write
permission in /etc/terminfo is not available.
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 values 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 rou-
tines.
Routine and Argument Names
Many curses routines have two or more versions. The routines prefixed
with w require a window argument. The routines prefixed with p require
a pad argument. Those without 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 coor-
dinates.
In each case, win is the window affected, and pad is the pad affected;
win and pad are always pointers to type WINDOW.
Option setting routines require a Boolean flag bf with the value TRUE
or FALSE; bf is always of type bool. Most of the data types used in
the library routines, such as WINDOW, SCREEN, bool, and chtype are de-
fined in <curses.h>. Types used for the terminfo routines such as TER-
MINAL are defined in <term.h>.
This manual page describes functions which may appear in any configura-
tion of the library. There are two common configurations of the li-
brary:
ncurses
the “normal” library, which handles 8-bit characters. The nor-
mal (8-bit) library stores characters combined with attributes
in chtype data.
Attributes alone (no corresponding character) may be stored in
chtype or the equivalent attr_t data. In either case, the data
is stored in something like an integer.
Each cell (row and column) in a WINDOW is stored as a chtype.
ncursesw
the so-called “wide” library, which handles multibyte charac-
ters (see the section on ALTERNATE CONFIGURATIONS). The “wide”
library includes all of the calls from the “normal” library.
It adds about one third more calls using data types which store
multibyte characters:
cchar_t
corresponds to chtype. However it is a structure, because
more data is stored than can fit into an integer. The
characters are large enough to require a full integer
value - and there may be more than one character per cell.
The video attributes and color are stored in separate
fields of the structure.
Each cell (row and column) in a WINDOW is stored as a
cchar_t.
The setcchar(3X) and getcchar(3X) functions store and re-
trieve the data from a cchar_t structure.
wchar_t
stores a “wide” character. Like chtype, this may be an
integer.
wint_t
stores a wchar_t or WEOF - not the same, though both may
have the same size.
The “wide” library provides new functions which are analogous
to functions in the “normal” library. There is a naming con-
vention which relates many of the normal/wide variants: a “_w”
is inserted into the name. For example, waddch becomes
wadd_wch.
Routine Name Index
The following table lists the curses routines provided in the “normal”
and “wide” libraries and the names of the manual pages on which they
are described. Routines flagged with “*” are ncurses-specific, not de-
scribed by XPG4 or present in SVr4.
curses Routine Name Manual Page Name
───────────────────────────────────────────────────
COLOR_PAIR color(3NCURSES)
PAIR_NUMBER attr(3NCURSES)
add_wch add_wch(3NCURSES)
add_wchnstr add_wchstr(3NCURSES)
add_wchstr add_wchstr(3NCURSES)
addch addch(3NCURSES)
addchnstr addchstr(3NCURSES)
addchstr addchstr(3NCURSES)
addnstr addstr(3NCURSES)
addnwstr addwstr(3NCURSES)
addstr addstr(3NCURSES)
addwstr addwstr(3NCURSES)
alloc_pair new_pair(3NCURSES)*
assume_default_colors default_colors(3NCURSES)*
attr_get attr(3NCURSES)
attr_off attr(3NCURSES)
attr_on attr(3NCURSES)
attr_set attr(3NCURSES)
attroff attr(3NCURSES)
attron attr(3NCURSES)
attrset attr(3NCURSES)
baudrate termattrs(3NCURSES)
beep beep(3NCURSES)
bkgd bkgd(3NCURSES)
bkgdset bkgd(3NCURSES)
bkgrnd bkgrnd(3NCURSES)
bkgrndset bkgrnd(3NCURSES)
border border(3NCURSES)
border_set border_set(3NCURSES)
box border(3NCURSES)
box_set border_set(3NCURSES)
can_change_color color(3NCURSES)
cbreak inopts(3NCURSES)
chgat attr(3NCURSES)
clear clear(3NCURSES)
clearok outopts(3NCURSES)
clrtobot clear(3NCURSES)
clrtoeol clear(3NCURSES)
color_content color(3NCURSES)
color_set attr(3NCURSES)
copywin overlay(3NCURSES)
curs_set kernel(3NCURSES)
curses_trace trace(3NCURSES)*
curses_version extensions(3NCURSES)*
def_prog_mode kernel(3NCURSES)
def_shell_mode kernel(3NCURSES)
define_key define_key(3NCURSES)*
del_curterm terminfo(3NCURSES)
delay_output util(3NCURSES)
delch delch(3NCURSES)
deleteln deleteln(3NCURSES)
delscreen initscr(3NCURSES)
delwin window(3NCURSES)
derwin window(3NCURSES)
doupdate refresh(3NCURSES)
dupwin window(3NCURSES)
echo inopts(3NCURSES)
echo_wchar add_wch(3NCURSES)
echochar addch(3NCURSES)
endwin initscr(3NCURSES)
erase clear(3NCURSES)
erasechar termattrs(3NCURSES)
erasewchar termattrs(3NCURSES)
exit_curses memleaks(3NCURSES)*
exit_terminfo memleaks(3NCURSES)*
extended_color_content color(3NCURSES)*
extended_pair_content color(3NCURSES)*
extended_slk_color slk(3NCURSES)*
filter util(3NCURSES)
find_pair new_pair(3NCURSES)*
flash beep(3NCURSES)
flushinp util(3NCURSES)
free_pair new_pair(3NCURSES)*
get_wch get_wch(3NCURSES)
get_wstr get_wstr(3NCURSES)
getattrs attr(3NCURSES)
getbegx legacy(3NCURSES)*
getbegy legacy(3NCURSES)*
getbegyx getyx(3NCURSES)
getbkgd bkgd(3NCURSES)
getbkgrnd bkgrnd(3NCURSES)
getcchar getcchar(3NCURSES)
getch getch(3NCURSES)
getcurx legacy(3NCURSES)*
getcury legacy(3NCURSES)*
getmaxx legacy(3NCURSES)*
getmaxy legacy(3NCURSES)*
getmaxyx getyx(3NCURSES)
getmouse mouse(3NCURSES)*
getn_wstr get_wstr(3NCURSES)
getnstr getstr(3NCURSES)
getparx legacy(3NCURSES)*
getpary legacy(3NCURSES)*
getparyx getyx(3NCURSES)
getstr getstr(3NCURSES)
getsyx kernel(3NCURSES)
getwin util(3NCURSES)
getyx getyx(3NCURSES)
halfdelay inopts(3NCURSES)
has_colors color(3NCURSES)
has_ic termattrs(3NCURSES)
has_il termattrs(3NCURSES)
has_key getch(3NCURSES)*
has_mouse mouse(3NCURSES)*
hline border(3NCURSES)
hline_set border_set(3NCURSES)
idcok outopts(3NCURSES)
idlok outopts(3NCURSES)
immedok outopts(3NCURSES)
in_wch in_wch(3NCURSES)
in_wchnstr in_wchstr(3NCURSES)
in_wchstr in_wchstr(3NCURSES)
inch inch(3NCURSES)
inchnstr inchstr(3NCURSES)
inchstr inchstr(3NCURSES)
init_color color(3NCURSES)
init_extended_color color(3NCURSES)*
init_extended_pair color(3NCURSES)*
init_pair color(3NCURSES)
initscr initscr(3NCURSES)
innstr instr(3NCURSES)
innwstr inwstr(3NCURSES)
ins_nwstr ins_wstr(3NCURSES)
ins_wch ins_wch(3NCURSES)
ins_wstr ins_wstr(3NCURSES)
insch insch(3NCURSES)
insdelln deleteln(3NCURSES)
insertln deleteln(3NCURSES)
insnstr insstr(3NCURSES)
insstr insstr(3NCURSES)
instr instr(3NCURSES)
intrflush inopts(3NCURSES)
inwstr inwstr(3NCURSES)
is_cleared opaque(3NCURSES)*
is_idcok opaque(3NCURSES)*
is_idlok opaque(3NCURSES)*
is_immedok opaque(3NCURSES)*
is_keypad opaque(3NCURSES)*
is_leaveok opaque(3NCURSES)*
is_linetouched touch(3NCURSES)
is_nodelay opaque(3NCURSES)*
is_notimeout opaque(3NCURSES)*
is_pad opaque(3NCURSES)*
is_scrollok opaque(3NCURSES)*
is_subwin opaque(3NCURSES)*
is_syncok opaque(3NCURSES)*
is_term_resized resizeterm(3NCURSES)*
is_wintouched touch(3NCURSES)
isendwin initscr(3NCURSES)
key_defined key_defined(3NCURSES)*
key_name util(3NCURSES)
keybound keybound(3NCURSES)*
keyname util(3NCURSES)
keyok keyok(3NCURSES)*
keypad inopts(3NCURSES)
killchar termattrs(3NCURSES)
killwchar termattrs(3NCURSES)
leaveok outopts(3NCURSES)
longname termattrs(3NCURSES)
mcprint print(3NCURSES)*
meta inopts(3NCURSES)
mouse_trafo mouse(3NCURSES)*
mouseinterval mouse(3NCURSES)*
mousemask mouse(3NCURSES)*
move move(3NCURSES)
mvadd_wch add_wch(3NCURSES)
mvadd_wchnstr add_wchstr(3NCURSES)
mvadd_wchstr add_wchstr(3NCURSES)
mvaddch addch(3NCURSES)
mvaddchnstr addchstr(3NCURSES)
mvaddchstr addchstr(3NCURSES)
mvaddnstr addstr(3NCURSES)
mvaddnwstr addwstr(3NCURSES)
mvaddstr addstr(3NCURSES)
mvaddwstr addwstr(3NCURSES)
mvchgat attr(3NCURSES)
mvcur terminfo(3NCURSES)
mvdelch delch(3NCURSES)
mvderwin window(3NCURSES)
mvget_wch get_wch(3NCURSES)
mvget_wstr get_wstr(3NCURSES)
mvgetch getch(3NCURSES)
mvgetn_wstr get_wstr(3NCURSES)
mvgetnstr getstr(3NCURSES)
mvgetstr getstr(3NCURSES)
mvhline border(3NCURSES)
mvhline_set border_set(3NCURSES)
mvin_wch in_wch(3NCURSES)
mvin_wchnstr in_wchstr(3NCURSES)
mvin_wchstr in_wchstr(3NCURSES)
mvinch inch(3NCURSES)
mvinchnstr inchstr(3NCURSES)
mvinchstr inchstr(3NCURSES)
mvinnstr instr(3NCURSES)
mvinnwstr inwstr(3NCURSES)
mvins_nwstr ins_wstr(3NCURSES)
mvins_wch ins_wch(3NCURSES)
mvins_wstr ins_wstr(3NCURSES)
mvinsch insch(3NCURSES)
mvinsnstr insstr(3NCURSES)
mvinsstr insstr(3NCURSES)
mvinstr instr(3NCURSES)
mvinwstr inwstr(3NCURSES)
mvprintw printw(3NCURSES)
mvscanw scanw(3NCURSES)
mvvline border(3NCURSES)
mvvline_set border_set(3NCURSES)
mvwadd_wch add_wch(3NCURSES)
mvwadd_wchnstr add_wchstr(3NCURSES)
mvwadd_wchstr add_wchstr(3NCURSES)
mvwaddch addch(3NCURSES)
mvwaddchnstr addchstr(3NCURSES)
mvwaddchstr addchstr(3NCURSES)
mvwaddnstr addstr(3NCURSES)
mvwaddnwstr addwstr(3NCURSES)
mvwaddstr addstr(3NCURSES)
mvwaddwstr addwstr(3NCURSES)
mvwchgat attr(3NCURSES)
mvwdelch delch(3NCURSES)
mvwget_wch get_wch(3NCURSES)
mvwget_wstr get_wstr(3NCURSES)
mvwgetch getch(3NCURSES)
mvwgetn_wstr get_wstr(3NCURSES)
mvwgetnstr getstr(3NCURSES)
mvwgetstr getstr(3NCURSES)
mvwhline border(3NCURSES)
mvwhline_set border_set(3NCURSES)
mvwin window(3NCURSES)
mvwin_wch in_wch(3NCURSES)
mvwin_wchnstr in_wchstr(3NCURSES)
mvwin_wchstr in_wchstr(3NCURSES)
mvwinch inch(3NCURSES)
mvwinchnstr inchstr(3NCURSES)
mvwinchstr inchstr(3NCURSES)
mvwinnstr instr(3NCURSES)
mvwinnwstr inwstr(3NCURSES)
mvwins_nwstr ins_wstr(3NCURSES)
mvwins_wch ins_wch(3NCURSES)
mvwins_wstr ins_wstr(3NCURSES)
mvwinsch insch(3NCURSES)
mvwinsnstr insstr(3NCURSES)
mvwinsstr insstr(3NCURSES)
mvwinstr instr(3NCURSES)
mvwinwstr inwstr(3NCURSES)
mvwprintw printw(3NCURSES)
mvwscanw scanw(3NCURSES)
mvwvline border(3NCURSES)
mvwvline_set border_set(3NCURSES)
napms kernel(3NCURSES)
newpad pad(3NCURSES)
newterm initscr(3NCURSES)
newwin window(3NCURSES)
nl inopts(3NCURSES)
nocbreak inopts(3NCURSES)
nodelay inopts(3NCURSES)
noecho inopts(3NCURSES)
nofilter util(3NCURSES)*
nonl inopts(3NCURSES)
noqiflush inopts(3NCURSES)
noraw inopts(3NCURSES)
notimeout inopts(3NCURSES)
overlay overlay(3NCURSES)
overwrite overlay(3NCURSES)
pair_content color(3NCURSES)
pecho_wchar pad(3NCURSES)*
pechochar pad(3NCURSES)
pnoutrefresh pad(3NCURSES)
prefresh pad(3NCURSES)
printw printw(3NCURSES)
putp terminfo(3NCURSES)
putwin util(3NCURSES)
qiflush inopts(3NCURSES)
raw inopts(3NCURSES)
redrawwin refresh(3NCURSES)
refresh refresh(3NCURSES)
reset_color_pairs color(3NCURSES)*
reset_prog_mode kernel(3NCURSES)
reset_shell_mode kernel(3NCURSES)
resetty kernel(3NCURSES)
resize_term resizeterm(3NCURSES)*
resizeterm resizeterm(3NCURSES)*
restartterm terminfo(3NCURSES)
ripoffline kernel(3NCURSES)
savetty kernel(3NCURSES)
scanw scanw(3NCURSES)
scr_dump scr_dump(3NCURSES)
scr_init scr_dump(3NCURSES)
scr_restore scr_dump(3NCURSES)
scr_set scr_dump(3NCURSES)
scrl scroll(3NCURSES)
scroll scroll(3NCURSES)
scrollok outopts(3NCURSES)
set_curterm terminfo(3NCURSES)
set_term initscr(3NCURSES)
setcchar getcchar(3NCURSES)
setscrreg outopts(3NCURSES)
setsyx kernel(3NCURSES)
setupterm terminfo(3NCURSES)
slk_attr slk(3NCURSES)*
slk_attr_off slk(3NCURSES)
slk_attr_on slk(3NCURSES)
slk_attr_set slk(3NCURSES)
slk_attroff slk(3NCURSES)
slk_attron slk(3NCURSES)
slk_attrset slk(3NCURSES)
slk_clear slk(3NCURSES)
slk_color slk(3NCURSES)
slk_init slk(3NCURSES)
slk_label slk(3NCURSES)
slk_noutrefresh slk(3NCURSES)
slk_refresh slk(3NCURSES)
slk_restore slk(3NCURSES)
slk_set slk(3NCURSES)
slk_touch slk(3NCURSES)
slk_wset slk(3NCURSES)*
standend attr(3NCURSES)
standout attr(3NCURSES)
start_color color(3NCURSES)
subpad pad(3NCURSES)
subwin window(3NCURSES)
syncok window(3NCURSES)
term_attrs termattrs(3NCURSES)
termattrs termattrs(3NCURSES)
termname termattrs(3NCURSES)
tgetent termcap(3NCURSES)
tgetflag termcap(3NCURSES)
tgetnum termcap(3NCURSES)
tgetstr termcap(3NCURSES)
tgoto termcap(3NCURSES)
tigetflag terminfo(3NCURSES)
tigetnum terminfo(3NCURSES)
tigetstr terminfo(3NCURSES)
timeout inopts(3NCURSES)
tiparm terminfo(3NCURSES)*
touchline touch(3NCURSES)
touchwin touch(3NCURSES)
tparm terminfo(3NCURSES)
tputs termcap(3NCURSES)
tputs terminfo(3NCURSES)
trace trace(3NCURSES)*
typeahead inopts(3NCURSES)
unctrl util(3NCURSES)
unget_wch get_wch(3NCURSES)
ungetch getch(3NCURSES)
ungetmouse mouse(3NCURSES)*
untouchwin touch(3NCURSES)
use_default_colors default_colors(3NCURSES)*
use_env util(3NCURSES)
use_extended_names extensions(3NCURSES)*
use_legacy_coding legacy_coding(3NCURSES)*
use_tioctl util(3NCURSES)*
vid_attr terminfo(3NCURSES)
vid_puts terminfo(3NCURSES)
vidattr terminfo(3NCURSES)
vidputs terminfo(3NCURSES)
vline border(3NCURSES)
vline_set border_set(3NCURSES)
vw_printw printw(3NCURSES)
vw_scanw scanw(3NCURSES)
vwprintw printw(3NCURSES)
vwscanw scanw(3NCURSES)
wadd_wch add_wch(3NCURSES)
wadd_wchnstr add_wchstr(3NCURSES)
wadd_wchstr add_wchstr(3NCURSES)
waddch addch(3NCURSES)
waddchnstr addchstr(3NCURSES)
waddchstr addchstr(3NCURSES)
waddnstr addstr(3NCURSES)
waddnwstr addwstr(3NCURSES)
waddstr addstr(3NCURSES)
waddwstr addwstr(3NCURSES)
wattr_get attr(3NCURSES)
wattr_off attr(3NCURSES)
wattr_on attr(3NCURSES)
wattr_set attr(3NCURSES)
wattroff attr(3NCURSES)
wattron attr(3NCURSES)
wattrset attr(3NCURSES)
wbkgd bkgd(3NCURSES)
wbkgdset bkgd(3NCURSES)
wbkgrnd bkgrnd(3NCURSES)
wbkgrndset bkgrnd(3NCURSES)
wborder border(3NCURSES)
wborder_set border_set(3NCURSES)
wchgat attr(3NCURSES)
wclear clear(3NCURSES)
wclrtobot clear(3NCURSES)
wclrtoeol clear(3NCURSES)
wcolor_set attr(3NCURSES)
wcursyncup window(3NCURSES)
wdelch delch(3NCURSES)
wdeleteln deleteln(3NCURSES)
wecho_wchar add_wch(3NCURSES)
wechochar addch(3NCURSES)
wenclose mouse(3NCURSES)*
werase clear(3NCURSES)
wget_wch get_wch(3NCURSES)
wget_wstr get_wstr(3NCURSES)
wgetbkgrnd bkgrnd(3NCURSES)
wgetch getch(3NCURSES)
wgetdelay opaque(3NCURSES)*
wgetn_wstr get_wstr(3NCURSES)
wgetnstr getstr(3NCURSES)
wgetparent opaque(3NCURSES)*
wgetscrreg opaque(3NCURSES)*
wgetstr getstr(3NCURSES)
whline border(3NCURSES)
whline_set border_set(3NCURSES)
win_wch in_wch(3NCURSES)
win_wchnstr in_wchstr(3NCURSES)
win_wchstr in_wchstr(3NCURSES)
winch inch(3NCURSES)
winchnstr inchstr(3NCURSES)
winchstr inchstr(3NCURSES)
winnstr instr(3NCURSES)
winnwstr inwstr(3NCURSES)
wins_nwstr ins_wstr(3NCURSES)
wins_wch ins_wch(3NCURSES)
wins_wstr ins_wstr(3NCURSES)
winsch insch(3NCURSES)
winsdelln deleteln(3NCURSES)
winsertln deleteln(3NCURSES)
winsnstr insstr(3NCURSES)
winsstr insstr(3NCURSES)
winstr instr(3NCURSES)
winwstr inwstr(3NCURSES)
wmouse_trafo mouse(3NCURSES)*
wmove move(3NCURSES)
wnoutrefresh refresh(3NCURSES)
wprintw printw(3NCURSES)
wredrawln refresh(3NCURSES)
wrefresh refresh(3NCURSES)
wresize wresize(3NCURSES)*
wscanw scanw(3NCURSES)
wscrl scroll(3NCURSES)
wsetscrreg outopts(3NCURSES)
wstandend attr(3NCURSES)
wstandout attr(3NCURSES)
wsyncdown window(3NCURSES)
wsyncup window(3NCURSES)
wtimeout inopts(3NCURSES)
wtouchln touch(3NCURSES)
wunctrl util(3NCURSES)
wvline border(3NCURSES)
wvline_set border_set(3NCURSES)
Depending on the configuration, additional sets of functions may be
available:
memleaks(3NCURSES) - curses memory-leak checking
sp_funcs(3NCURSES) - curses screen-pointer extension
threads(3NCURSES) - curses thread support
trace(3NCURSES) - curses debugging routines
RETURN VALUE
Routines that return an integer return ERR upon failure and an integer
value other than ERR upon successful completion, unless otherwise noted
in the routine descriptions.
As a general rule, routines check for null pointers passed as parame-
ters, and handle this as an error.
All macros return the value of the w version, except setscrreg,
wsetscrreg, getyx, getbegyx, and 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).
Functions with a “mv” prefix first perform a cursor movement using
wmove, and return an error if the position is outside the window, or if
the window pointer is null. Most “mv”-prefixed functions (except vari-
adic functions such as mvprintw) are provided both as macros and func-
tions.
Routines that return pointers return NULL on error.
ENVIRONMENT
The following environment symbols are useful for customizing the run-
time behavior of the ncurses library. The most important ones have
been already discussed in detail.
CC command-character
When set, change occurrences of the command_character (i.e., the cmdch
capability) of the loaded terminfo entries to the value of this vari-
able. Very few terminfo entries provide this feature.
Because this name is also used in development environments to represent
the C compiler's name, ncurses ignores it if it does not happen to be a
single character.
BAUDRATE
The debugging library checks this environment variable when the appli-
cation has redirected output to a file. The variable'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.
COLUMNS
Specify the width of the screen in characters. Applications running in
a windowing environment usually 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. 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. How-
ever, setting COLUMNS and/or LINES overrides the library's use of the
screen size obtained from the operating system.
Either COLUMNS or LINES symbols may be specified independently. This
is mainly useful to circumvent legacy misfeatures of terminal descrip-
tions, e.g., xterm which commonly specifies a 65 line screen. For best
results, lines and cols should not be specified in a terminal descrip-
tion for terminals which are run as emulations.
Use the use_env function to disable all use of external environment
(but not including system calls) to determine the screen size. Use the
use_tioctl function to update COLUMNS or LINES to match the screen size
obtained from system calls or the terminal database.
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 variable
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 character sequences re-
ceived from the xterm. If your application makes heavy use of multi-
ple-clicking, you may wish to lengthen this default value because the
timeout applies to the composed multi-click event as well as the indi-
vidual clicks.
In addition to the environment variable, this implementation provides a
global variable with the same name. Portable applications should not
rely upon the presence of ESCDELAY in either form, but setting the en-
vironment variable rather than the global variable does not create
problems when compiling an application.
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 COL-
UMNS for a detailed description.
MOUSE_BUTTONS_123
This applies only to the OS/2 EMX port. It specifies the order of but-
tons on the mouse. OS/2 numbers a 3-button mouse inconsistently from
other platforms:
1 = left
2 = right
3 = middle.
This variable lets you customize the mouse. The variable must be three
numeric digits 1-3 in any order, e.g., 123 or 321. If it is not speci-
fied, ncurses uses 132.
NCURSES_ASSUMED_COLORS
Override the compiled-in assumption that the terminal's default colors
are white-on-black (see default_colors(3NCURSES)). You may set the
foreground and background color values with this environment variable
by proving a 2-element list: foreground,background. For example, to
tell ncurses to not assume anything about the colors, set this to
"-1,-1". To make it green-on-black, set it to "2,0". Any positive
value from zero to the terminfo max_colors value is allowed.
NCURSES_CONSOLE2
This applies only to the MinGW port of ncurses.
The Console2 program's handling of the Microsoft Console API call Cre-
ateConsoleScreenBuffer is defective. Applications which use this will
hang. However, it is possible to simulate the action of this call by
mapping coordinates, explicitly saving and restoring the original
screen contents. Setting the environment variable NCGDB has the same
effect.
NCURSES_GPM_TERMS
This applies only to ncurses configured to use the GPM interface.
If present, the environment variable is a list of one or more terminal
names against which the TERM environment variable is matched. Setting
it to an empty value disables the GPM interface; using the built-in
support for xterm, etc.
If the environment variable is absent, ncurses will attempt to open GPM
if TERM contains “linux”.
NCURSES_NO_HARD_TABS
Ncurses may use tabs as part of the cursor movement optimization. In
some cases, your terminal driver may not handle these properly. Set
this environment variable to disable the feature. You can also adjust
your stty(1) settings to avoid the problem.
NCURSES_NO_MAGIC_COOKIE
Some terminals use a magic-cookie feature which requires special han-
dling to make highlighting and other video attributes display properly.
You can suppress the highlighting entirely for these terminals by set-
ting this environment variable.
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 applications.
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 ap-
plication is the management of dataflow, i.e., timing. Unless a hard-
ware 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 de-
lay times embedded. You may wish to use these descriptions, but not
want to pay the performance penalty.
Set the NCURSES_NO_PADDING environment variable to disable all but
mandatory padding. Mandatory padding is used as a part of special con-
trol sequences such as flash.
NCURSES_NO_SETBUF
This setting is obsolete. Before changes
• started with 5.9 patch 20120825 and
• continued though 5.9 patch 20130126
ncurses enabled buffered output during terminal initialization. This
was done (as in SVr4 curses) for performance reasons. For testing pur-
poses, both of ncurses and certain applications, this feature was made
optional. Setting the NCURSES_NO_SETBUF variable disabled output
buffering, leaving the output in the original (usually line buffered)
mode.
In the current implementation, ncurses performs its own buffering and
does not require this workaround. It does not modify the buffering of
the standard output.
The reason for the change was to make the behavior for interrupts and
other signals more robust. One drawback is that certain nonconven-
tional programs would mix ordinary stdio calls with ncurses calls and
(usually) work. This is no longer possible since ncurses is not using
the buffered standard output but its own output (to the same file de-
scriptor). As a special case, the low-level calls such as putp still
use the standard output. But high-level curses calls do not.
NCURSES_NO_UTF8_ACS
During initialization, the ncurses library checks for special cases
where VT100 line-drawing (and the corresponding alternate character set
capabilities) described in the terminfo are known to be missing.
Specifically, when running in a UTF-8 locale, the Linux console emula-
tor and the GNU screen program ignore these. Ncurses checks the TERM
environment variable for these. For other special cases, you should
set this environment variable. Doing this tells ncurses to use Unicode
values which correspond to the VT100 line-drawing glyphs. That works
for the special cases cited, and is likely to work for terminal emula-
tors.
When setting this variable, you should set it to a nonzero value. Set-
ting it to zero (or to a nonnumber) disables the special check for
“linux” and “screen”.
As an alternative to the environment variable, ncurses checks for an
extended terminfo capability U8. This is a numeric capability which
can be compiled using tic -x. For example
# linux console, if patched to provide working
# VT100 shift-in/shift-out, with corresponding font.
linux-vt100|linux console with VT100 line-graphics,
U8#0, use=linux,
# uxterm with vt100Graphics resource set to false
xterm-utf8|xterm relying on UTF-8 line-graphics,
U8#1, use=xterm,
The name “U8” is chosen to be two characters, to permit it to be used
by applications that use ncurses' termcap interface.
NCURSES_TRACE
During initialization, the ncurses debugging library checks the
NCURSES_TRACE environment variable. If it is defined, to a numeric
value, ncurses calls the trace function, using that value as the argu-
ment.
The argument values, which are defined in curses.h, provide several
types of information. When running with traces enabled, your applica-
tion will write the file trace to the current directory.
See trace(3NCURSES) for more information.
TERM
Denotes your terminal type. Each terminal type is distinct, though
many are similar.
TERM is commonly set by terminal emulators to help applications find a
workable terminal description. Some of those choose a popular approxi-
mation, e.g., “ansi”, “vt100”, “xterm” rather than an exact fit. Not
infrequently, your application will have problems with that approach,
e.g., incorrect function-key definitions.
If you set TERM in your environment, it has no effect on the operation
of the terminal emulator. It only affects the way applications work
within the terminal. Likewise, as a general rule (xterm(1) being a
rare exception), terminal emulators which allow you to specify TERM as
a parameter or configuration value do not change their behavior to
match that setting.
TERMCAP
If the ncurses library has been configured with termcap support,
ncurses will check for a terminal's description in termcap form if it
is not available in the terminfo database.
The TERMCAP environment variable contains either a terminal description
(with newlines stripped out), or a file name telling where the informa-
tion denoted by the TERM environment variable exists. In either case,
setting it directs ncurses to ignore the usual place for this informa-
tion, e.g., /etc/termcap.
TERMINFO
ncurses can be configured to read from multiple terminal databases.
The TERMINFO variable overrides the location for the default terminal
database. Terminal descriptions (in terminal format) are stored in
terminal databases:
• Normally these are stored in a directory tree, using subdirectories
named by the first letter of the terminal names therein.
This is the scheme used in System V, which legacy Unix systems use,
and the TERMINFO variable is used by curses applications on those
systems to override the default location of the terminal database.
• If ncurses is built to use hashed databases, then each entry in
this list may be the path of a hashed database file, e.g.,
/usr/share/terminfo.db
rather than
/usr/share/terminfo/
The hashed database uses less disk-space and is a little faster
than the directory tree. However, some applications assume the ex-
istence of the directory tree, reading it directly rather than us-
ing the terminfo library calls.
• If ncurses is built with a support for reading termcap files di-
rectly, then an entry in this list may be the path of a termcap
file.
• If the TERMINFO variable begins with “hex:” or “b64:”, ncurses uses
the remainder of that variable as a compiled terminal description.
You might produce the base64 format using infocmp(1):
TERMINFO="$(infocmp -0 -Q2 -q)"
export TERMINFO
The compiled description is used if it corresponds to the terminal
identified by the TERM variable.
Setting TERMINFO is the simplest, but not the only way to set location
of the default terminal database. The complete list of database loca-
tions in order follows:
• the last terminal database to which ncurses wrote, if any, is
searched first
• the location specified by the TERMINFO environment variable
• $HOME/.terminfo
• locations listed in the TERMINFO_DIRS environment variable
• one or more locations whose names are configured and compiled
into the ncurses library, i.e.,
• no default value (corresponding to the TERMINFO_DIRS vari-
able)
• /etc/terminfo (corresponding to the TERMINFO variable)
TERMINFO_DIRS
Specifies a list of locations to search for terminal descriptions.
Each location in the list is a terminal database as described in the
section on the TERMINFO variable. The list is separated by colons
(i.e., ":") on Unix, semicolons on OS/2 EMX.
There is no corresponding feature in System V terminfo; it is an exten-
sion developed for ncurses.
TERMPATH
If TERMCAP does not hold a file name then ncurses checks the TERMPATH
environment variable. This is a list of filenames separated by spaces
or colons (i.e., ":") on Unix, semicolons on OS/2 EMX.
If the TERMPATH environment variable 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.
ALTERNATE CONFIGURATIONS
Several different configurations are possible, depending on the config-
ure script options used when building ncurses. There are a few main
options whose effects are visible to the applications developer using
ncurses:
--disable-overwrite
The standard include for ncurses is as noted in SYNOPSIS:
#include <curses.h>
This option is used to avoid filename conflicts when ncurses is
not the main implementation of curses of the computer. If ncurses
is installed disabling overwrite, it puts its headers in a subdi-
rectory, e.g.,
#include <ncurses/curses.h>
It also omits a symbolic link which would allow you to use
-lcurses to build executables.
--enable-widec
The configure script renames the library and (if the --dis-
able-overwrite option is used) puts the header files in a differ-
ent subdirectory. All of the library names have a “w” appended to
them, i.e., instead of
-lncurses
you link with
-lncursesw
You must also enable the wide-character features in the header
file when compiling for the wide-character library to use the ex-
tended (wide-character) functions. The symbol which enables these
features has changed since XSI Curses, Issue 4:
• Originally, the wide-character feature required the symbol
_XOPEN_SOURCE_EXTENDED but that was only valid for XPG4
(1996).
• Later, that was deemed conflicting with _XOPEN_SOURCE defined
to 500.
• As of mid-2018, none of the features in this implementation
require a _XOPEN_SOURCE feature greater than 600. However,
X/Open Curses, Issue 7 (2009) recommends defining it to 700.
• Alternatively, you can enable the feature by defining
NCURSES_WIDECHAR with the caveat that some other header file
than curses.h may require a specific value for _XOPEN_SOURCE
(or a system-specific symbol).
The curses.h file which is installed for the wide-character li-
brary is designed to be compatible with the normal library's
header. Only the size of the WINDOW structure differs, and very
few applications require more than a pointer to WINDOWs.
If the headers are installed allowing overwrite, the wide-charac-
ter library's headers should be installed last, to allow applica-
tions to be built using either library from the same set of head-
ers.
--with-pthread
The configure script renames the library. All of the library
names have a “t” appended to them (before any “w” added by --en-
able-widec).
The global variables such as LINES are replaced by macros to allow
read-only access. At the same time, setter-functions are provided
to set these values. Some applications (very few) may require
changes to work with this convention.
--with-shared
--with-normal
--with-debug
--with-profile
The shared and normal (static) library names differ by their suf-
fixes, e.g., libncurses.so and libncurses.a. The debug and pro-
filing libraries add a “_g” and a “_p” to the root names respec-
tively, e.g., libncurses_g.a and libncurses_p.a.
--with-termlib
Low-level functions which do not depend upon whether the library
supports wide-characters, are provided in the tinfo library.
By doing this, it is possible to share the tinfo library between
wide/normal configurations as well as reduce the size of the li-
brary when only low-level functions are needed.
Those functions are described in these pages:
• extensions(3NCURSES) - miscellaneous curses extensions
• inopts(3NCURSES) - curses input options
• kernel(3NCURSES) - low-level curses routines
• termattrs(3NCURSES) - curses environment query routines
• termcap(3NCURSES) - curses emulation of termcap
• terminfo(3NCURSES) - curses interfaces to terminfo database
• util(3NCURSES) - miscellaneous curses utility routines
--with-trace
The trace function normally resides in the debug library, but it
is sometimes useful to configure this in the shared library. Con-
figure scripts should check for the function's existence rather
than assuming it is always in the debug library.
FILES
/usr/share/tabset
directory containing initialization files for the terminal capa-
bility database /etc/terminfo terminal capability database
SEE ALSO
terminfo(5) and related pages whose names begin “curs_” for detailed
routine descriptions.
curses_variables(3NCURSES)
user_caps(5) for user-defined capabilities
EXTENSIONS
The ncurses library can be compiled with an option (-DUSE_GETCAP) that
falls back to the old-style /etc/termcap 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 term-
cap 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 mouse(3NCURSES) manual
page for details.
The ncurses library includes facilities for responding to window resiz-
ing events, e.g., when running in an xterm. See the re-
sizeterm(3NCURSES) and wresize(3NCURSES) 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(3NCURSES) key_de-
fined(3NCURSES), and keyok(3NCURSES) manual pages for details.
The ncurses library can exploit the capabilities of terminals which im-
plement the ISO-6429 SGR 39 and SGR 49 controls, which allow an appli-
cation to reset the terminal to its original foreground and background
colors. From the users' perspective, the application is able to draw
colored text on a background whose color is set independently, provid-
ing better control over color contrasts. See the default_col-
ors(3NCURSES) manual page for details.
The ncurses library includes a function for directing application out-
put to a printer attached to the terminal device. See the
print(3NCURSES) manual page for details.
PORTABILITY
The ncurses library is intended to be BASE-level conformant with XSI
Curses. The EXTENDED XSI Curses functionality (including color sup-
port) is supported.
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.
Error checking
In many cases, X/Open Curses is vague about error conditions, omitting
some of the SVr4 documentation.
Unlike other implementations, this one checks parameters such as point-
ers to WINDOW structures to ensure they are not null. The main reason
for providing this behavior is to guard against programmer error. The
standard interface does not provide a way for the library to tell an
application which of several possible errors were detected. Relying on
this (or some other) extension will adversely affect the portability of
curses applications.
Extensions versus portability
Most of the extensions provided by ncurses have not been standardized.
Some have been incorporated into other implementations, such as PD-
Curses or NetBSD curses. Here are a few to consider:
• The routine has_key is not part of XPG4, nor is it present in SVr4.
See the getch(3NCURSES) manual page for details.
• The routine slk_attr is not part of XPG4, nor is it present in
SVr4. See the slk(3NCURSES) manual page for details.
• The routines getmouse, mousemask, ungetmouse, mouseinterval, and
wenclose relating to mouse interfacing are not part of XPG4, nor
are they present in SVr4. See the mouse(3NCURSES) manual page for
details.
• The routine mcprint was not present in any previous curses imple-
mentation. See the print(3NCURSES) manual page for details.
• The routine wresize is not part of XPG4, nor is it present in SVr4.
See the wresize(3NCURSES) manual page for details.
• The WINDOW structure's internal details can be hidden from applica-
tion programs. See opaque(3NCURSES) for the discussion of
is_scrollok, etc.
• This implementation can be configured to provide rudimentary sup-
port for multi-threaded applications. See threads(3NCURSES) for
details.
• This implementation can also be configured to provide a set of
functions which improve the ability to manage multiple screens.
See sp_funcs(3NCURSES) for details.
Padding differences
In historic curses versions, delays embedded in the capabilities cr,
ind, cub1, ff and tab activated corresponding delay bits in the UNIX
tty driver. In this implementation, all padding is done by sending NUL
bytes. This method is slightly more expensive, but narrows the inter-
face to the UNIX kernel significantly and increases the package's
portability correspondingly.
Header files
The header file <curses.h> automatically includes the header files
<stdio.h> and <unctrl.h>.
X/Open Curses has more to say, but does not finish the story:
The inclusion of <curses.h> may make visible all symbols from the
headers <stdio.h>, <term.h>, <termios.h>, and <wchar.h>.
Here is a more complete story:
• Starting with BSD curses, all implementations have included
<stdio.h>.
BSD curses included <curses.h> and <unctrl.h> from an internal
header "curses.ext" ("ext" was a short name for externs).
BSD curses used <stdio.h> internally (for printw and scanw), but
nothing in <curses.h> itself relied upon <stdio.h>.
• SVr2 curses added newterm(3X), which relies upon <stdio.h>. That
is, the function prototype uses FILE.
SVr4 curses added putwin and getwin, which also use <stdio.h>.
X/Open Curses documents all three of these functions.
SVr4 curses and X/Open Curses do not require the developer to in-
clude <stdio.h> before including <curses.h>. Both document curses
showing <curses.h> as the only required header.
As a result, standard <curses.h> will always include <stdio.h>.
• X/Open Curses is inconsistent with respect to SVr4 regarding <unc-
trl.h>.
As noted in util(3NCURSES), ncurses includes <unctrl.h> from
<curses.h> (like SVr4).
• X/Open's comments about <term.h> and <termios.h> may refer to HP-UX
and AIX:
HP-UX curses includes <term.h> from <curses.h> to declare setupterm
in curses.h, but ncurses (and Solaris curses) do not.
AIX curses includes <term.h> and <termios.h>. Again, ncurses (and
Solaris curses) do not.
• X/Open says that <curses.h> may include <term.h>, but there is no
requirement that it do that.
Some programs use functions declared in both <curses.h> and
<term.h>, and must include both headers in the same module. Very
old versions of AIX curses required including <curses.h> before in-
cluding <term.h>.
Because ncurses header files include the headers needed to define
datatypes used in the headers, ncurses header files can be included
in any order. But for portability, you should include <curses.h>
before <term.h>.
• X/Open Curses says "may make visible" because including a header
file does not necessarily make all symbols in it visible (there are
ifdef's to consider).
For instance, in ncurses <wchar.h> may be included if the proper
symbol is defined, and if ncurses is configured for wide-character
support. If the header is included, its symbols may be made visi-
ble. That depends on the value used for _XOPEN_SOURCE feature test
macro.
• X/Open Curses documents one required header, in a special case:
<stdarg.h> before <curses.h> to prototype the vw_printw and
vw_scanw functions (as well as the obsolete the vwprintw and vws-
canw functions). Each of those uses a va_list parameter.
The two obsolete functions were introduced in SVr3. The other
functions were introduced in X/Open Curses. In between, SVr4
curses provided for the possibility that an application might in-
clude either <varargs.h> or <stdarg.h>. Initially, that was done
by using void* for the va_list parameter. Later, a special type
(defined in <stdio.h>) was introduced, to allow for compiler type-
checking. That special type is always available, because <stdio.h>
is always included by <curses.h>.
None of the X/Open Curses implementations require an application to
include <stdarg.h> before <curses.h> because they either have al-
lowed for a special type, or (like ncurses) include <stdarg.h> di-
rectly to provide a portable interface.
NOTES
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 feature 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(3NCURSES)
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