Provided by: ncurses-doc_6.4-2_all 
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 replacement 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
PORTABILITY sections below and described in detail in the respective EXTENSIONS,
PORTABILITY and BUGS sections of individual man pages.
The ncurses library also provides many useful extensions, i.e., features 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 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 directory) that
describe curses actions. See also the section on ALTERNATE CONFIGURATIONS.
The ncurses package supports: overall screen, window and pad manipulation; output to
windows and pads; reading terminal input; control over terminal and curses input and
output options; environment query routines; color manipulation; use of soft label keys;
terminfo capabilities; 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 library before any of the
other routines that deal with windows and screens are used. The routine endwin(3X) 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:
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 environment 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 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(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 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 displayed.
See pad(3NCURSES) for more information.
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
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.
Environment variables
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 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 compiled 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 routines.
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 coordinates.
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 defined in <curses.h>. Types used for the terminfo routines
such as TERMINAL are defined in <term.h>.
This manual page describes functions which may appear in any configuration of the library.
There are two common configurations of the library:
ncurses
the “normal” library, which handles 8-bit characters. The normal (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 characters (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 retrieve 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 convention 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 described 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 parameters, 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 variadic functions such as mvprintw) are provided both as
macros and functions.
Routines that return pointers return NULL on error.
ENVIRONMENT
The following environment symbols are useful for customizing the runtime 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 variable. 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 application 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. However, 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 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 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 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.
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 environment 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 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 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 specified, 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
CreateConsoleScreenBuffer 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 handling to make
highlighting and other video attributes display properly. You can suppress the
highlighting entirely for these terminals by setting 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 application is the
management of dataflow, i.e., timing. Unless a hardware terminal is interfaced into a
terminal concentrator (which does flow control), it (or your application) must manage
dataflow, preventing 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 environment variable to disable all but mandatory padding.
Mandatory padding is used as a part of special control 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 purposes, 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 nonconventional 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 descriptor).
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 emulator 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 emulators.
When setting this variable, you should set it to a nonzero value. Setting 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 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.
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 approximation, 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 information denoted by the TERM
environment variable exists. In either case, setting it directs ncurses to ignore the
usual place for this information, 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 existence of the directory tree, reading
it directly rather than using the terminfo library calls.
• If ncurses is built with a support for reading termcap files directly, 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 locations 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 variable)
• /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 extension 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 configure 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 subdirectory, 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 --disable-overwrite option is
used) puts the header files in a different 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 extended (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 library 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-character library's headers
should be installed last, to allow applications to be built using either library from
the same set of headers.
--with-pthread
The configure script renames the library. All of the library names have a “t”
appended to them (before any “w” added by --enable-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 suffixes, e.g.,
libncurses.so and libncurses.a. The debug and profiling libraries add a “_g” and a
“_p” to the root names respectively, 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 library 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. Configure 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 capability 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 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 mouse(3NCURSES) 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(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_defined(3NCURSES), and keyok(3NCURSES) manual pages for details.
The ncurses library can exploit the capabilities of terminals which implement the ISO-6429
SGR 39 and SGR 49 controls, 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 colored text on a background whose color is set independently, providing
better control over color contrasts. See the default_colors(3NCURSES) manual page for
details.
The ncurses library includes a function for directing application output 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 support) 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 pointers 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 PDCurses 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 implementation. 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 application programs. See
opaque(3NCURSES) for the discussion of is_scrollok, etc.
• This implementation can be configured to provide rudimentary support 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 interface 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 include <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 <unctrl.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 including <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 visible. 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 vwscanw 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 include 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 allowed for a special type, or (like
ncurses) include <stdarg.h> directly 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)