ncurses(3) UNIX Programmer's Manual ncurses(3)
ncurses - CRT screen handling and optimization package
#include <curses.h>
The ncurses library routines give the user a terminal-
independent method of updating character screens with rea-
sonable optimization. This implementation is ``new curses''
(ncurses) and is the approved replacement for 4.4BSD classic
curses, which has been discontinued.
The ncurses routines emulate the curses(3) library of System
V Release 4 UNIX, and the XPG4 curses standard (XSI curses)
but the ncurses library is freely redistributable in source
form. Differences from the SVr4 curses are summarized under
the EXTENSIONS and PORTABILITY sections below and described
in detail in the respective EXTENSIONS, PORTABILITY and BUGS
sections of individual man pages.
A program using these routines must be linked with the
-lncurses option, or (if it has been generated) with the
debugging library -lncurses_g. (Your system integrator may
also have installed these libraries under the names -lcurses
and -lcurses_g.) The ncurses_g library generates trace logs
(in a file called 'trace' in the current directory) that
describe curses actions.
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.
To initialize the routines, the routine initscr or newterm
must be called before any of the other routines that deal
with windows and screens are used. The routine endwin must
be called before exiting. To get character-at-a-time input
without echoing (most interactive, screen oriented programs
want this), the following sequence should be used:
initscr(); cbreak(); noecho();
Most programs would additionally use the sequence:
nonl();
intrflush(stdscr, FALSE);
keypad(stdscr, TRUE);
Before a curses program is run, the tab stops of the
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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.]
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(3) 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 which the most basic routines are move and addch.
More general versions of these routines are included with
names beginning with w, allowing the user to specify a win-
dow. The routines not beginning with w affect stdscr.)
After using routines to manipulate a window, refresh is
called, telling curses to make the user's CRT screen look
like stdscr. The characters in a window are actually of
type chtype, (character and attribute data) so that other
information about the character may also be stored with each
character.
Special windows called pads may also be manipulated. These
are windows which are not constrained to the size of the
screen and whose contents need not be completely displayed.
See curs_pad(3) for more information.
In addition to drawing characters on the screen, video
attributes and colors may be supported, causing the charac-
ters to show up in such modes as underlined, in reverse
video, or in color on terminals that support such display
enhancements. Line drawing characters may be specified to
be output. On input, curses is also able to translate arrow
and function keys that transmit escape sequences into single
values. The video attributes, line drawing characters, and
input values use names, defined in <curses.h>, such as
A_REVERSE, ACS_HLINE, and KEY_LEFT.
If the environment variables LINES and COLUMNS are set, or
if the program is executing in a window environment, line
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and column information in the environment will override
information read by terminfo. This would effect a program
running in an AT&T 630 layer, for example, where the size of
a screen is changeable (see ENVIRONMENT).
If the environment variable TERMINFO is defined, any 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
/usr/share/terminfo/a/att4424.
(The a is copied from the first letter of att4424 to avoid
creation of huge directories.) However, if TERMINFO is set
to $HOME/myterms, curses first checks
$HOME/myterms/a/att4424,
and if that fails, it then checks
/usr/share/terminfo/a/att4424.
This is useful for developing experimental definitions or
when write permission in /usr/share/terminfo is not avail-
able.
The integer variables LINES and COLS are defined in
<curses.h> and will be filled in by initscr with the size of
the screen. The constants TRUE and FALSE have the 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 rou-
tines prefixed with w require a window argument. The rou-
tines 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
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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. The vari-
ables ch and attrs below are always of type chtype. The
types WINDOW, SCREEN, bool, and chtype are defined in
<curses.h>. The type TERMINAL is defined in <term.h>. All
other arguments are integers.
Routine Name Index
The following table lists each curses routine and the name
of the manual page on which it is described. Routines
flagged with `*' are ncurses-specific, not described by XPG4
or present in SVr4.
curses Routine Name Manual Page Name
__________________________________________
COLOR_PAIR curs_color(3)
PAIR_NUMBER curs_attr(3)
_nc_tracebits curs_trace(3)*
_traceattr curs_trace(3)*
_traceattr2 curs_trace(3)*
_tracechar curs_trace(3)*
_tracechtype curs_trace(3)*
_tracechtype2 curs_trace(3)*
_tracedump curs_trace(3)*
_tracef curs_trace(3)*
_tracemouse curs_trace(3)*
add_wch curs_add_wch(3)
add_wchnstr curs_add_wchstr(3)
add_wchstr curs_add_wchstr(3)
addch curs_addch(3)
addchnstr curs_addchstr(3)
addchstr curs_addchstr(3)
addnstr curs_addstr(3)
addnwstr curs_addwstr(3)
addstr curs_addstr(3)
addwstr curs_addwstr(3)
assume_default_colors default_colors(3)*
attr_get curs_attr(3)
attr_off curs_attr(3)
attr_on curs_attr(3)
attr_set curs_attr(3)
attroff curs_attr(3)
attron curs_attr(3)
attrset curs_attr(3)
baudrate curs_termattrs(3)
beep curs_beep(3)
bkgd curs_bkgd(3)
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bkgdset curs_bkgd(3)
bkgrnd curs_bkgrnd(3)
bkgrndset curs_bkgrnd(3)
border curs_border(3)
border_set curs_border_set(3)
box curs_border(3)
box_set curs_border_set(3)
can_change_color curs_color(3)
cbreak curs_inopts(3)
chgat curs_attr(3)
clear curs_clear(3)
clearok curs_outopts(3)
clrtobot curs_clear(3)
clrtoeol curs_clear(3)
color_content curs_color(3)
color_set curs_attr(3)
copywin curs_overlay(3)
curs_set curs_kernel(3)
curses_version curs_extend(3)*
def_prog_mode curs_kernel(3)
def_shell_mode curs_kernel(3)
define_key define_key(3)*
del_curterm curs_terminfo(3)
delay_output curs_util(3)
delch curs_delch(3)
deleteln curs_deleteln(3)
delscreen curs_initscr(3)
delwin curs_window(3)
derwin curs_window(3)
doupdate curs_refresh(3)
dupwin curs_window(3)
echo curs_inopts(3)
echo_wchar curs_add_wch(3)
echochar curs_addch(3)
endwin curs_initscr(3)
erase curs_clear(3)
erasechar curs_termattrs(3)
erasewchar curs_termattrs(3)
filter curs_util(3)
flash curs_beep(3)
flushinp curs_util(3)
get_wch curs_get_wch(3)
get_wstr curs_get_wstr(3)
getbegyx curs_getyx(3)
getbkgd curs_bkgd(3)
getbkgrnd curs_bkgrnd(3)
getcchar curs_getcchar(3)
getch curs_getch(3)
getmaxyx curs_getyx(3)
getmouse curs_mouse(3)*
getn_wstr curs_get_wstr(3)
getnstr curs_getstr(3)
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getparyx curs_getyx(3)
getstr curs_getstr(3)
getsyx curs_kernel(3)
getwin curs_util(3)
getyx curs_getyx(3)
halfdelay curs_inopts(3)
has_colors curs_color(3)
has_ic curs_termattrs(3)
has_il curs_termattrs(3)
has_key curs_getch(3)*
hline curs_border(3)
hline_set curs_border_set(3)
idcok curs_outopts(3)
idlok curs_outopts(3)
immedok curs_outopts(3)
in_wch curs_in_wch(3)
in_wchnstr curs_in_wchstr(3)
in_wchstr curs_in_wchstr(3)
inch curs_inch(3)
inchnstr curs_inchstr(3)
inchstr curs_inchstr(3)
init_color curs_color(3)
init_pair curs_color(3)
initscr curs_initscr(3)
innstr curs_instr(3)
innwstr curs_inwstr(3)
ins_nwstr curs_ins_wstr(3)
ins_wch curs_ins_wch(3)
ins_wstr curs_ins_wstr(3)
insch curs_insch(3)
insdelln curs_deleteln(3)
insertln curs_deleteln(3)
insnstr curs_insstr(3)
insstr curs_insstr(3)
instr curs_instr(3)
intrflush curs_inopts(3)
inwstr curs_inwstr(3)
is_linetouched curs_touch(3)
is_wintouched curs_touch(3)
isendwin curs_initscr(3)
key_defined key_defined(3)*
key_name curs_util(3)
keybound keybound(3)*
keyname curs_util(3)
keyok keyok(3)*
keypad curs_inopts(3)
killchar curs_termattrs(3)
killwchar curs_termattrs(3)
leaveok curs_outopts(3)
longname curs_termattrs(3)
mcprint curs_print(3)*
meta curs_inopts(3)
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mouse_trafo curs_mouse(3)*
mouseinterval curs_mouse(3)*
mousemask curs_mouse(3)*
move curs_move(3)
mvadd_wch curs_add_wch(3)
mvadd_wchnstr curs_add_wchstr(3)
mvadd_wchstr curs_add_wchstr(3)
mvaddch curs_addch(3)
mvaddchnstr curs_addchstr(3)
mvaddchstr curs_addchstr(3)
mvaddnstr curs_addstr(3)
mvaddnwstr curs_addwstr(3)
mvaddstr curs_addstr(3)
mvaddwstr curs_addwstr(3)
mvchgat curs_attr(3)
mvcur curs_terminfo(3)
mvdelch curs_delch(3)
mvderwin curs_window(3)
mvget_wch curs_get_wch(3)
mvget_wstr curs_get_wstr(3)
mvgetch curs_getch(3)
mvgetn_wstr curs_get_wstr(3)
mvgetnstr curs_getstr(3)
mvgetstr curs_getstr(3)
mvhline curs_border(3)
mvhline_set curs_border_set(3)
mvin_wch curs_in_wch(3)
mvin_wchnstr curs_in_wchstr(3)
mvin_wchstr curs_in_wchstr(3)
mvinch curs_inch(3)
mvinchnstr curs_inchstr(3)
mvinchstr curs_inchstr(3)
mvinnstr curs_instr(3)
mvinnwstr curs_inwstr(3)
mvins_nwstr curs_ins_wstr(3)
mvins_wch curs_ins_wch(3)
mvins_wstr curs_ins_wstr(3)
mvinsch curs_insch(3)
mvinsnstr curs_insstr(3)
mvinsstr curs_insstr(3)
mvinstr curs_instr(3)
mvinwstr curs_inwstr(3)
mvprintw curs_printw(3)
mvscanw curs_scanw(3)
mvvline curs_border(3)
mvvline_set curs_border_set(3)
mvwadd_wch curs_add_wch(3)
mvwadd_wchnstr curs_add_wchstr(3)
mvwadd_wchstr curs_add_wchstr(3)
mvwaddch curs_addch(3)
mvwaddchnstr curs_addchstr(3)
mvwaddchstr curs_addchstr(3)
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mvwaddnstr curs_addstr(3)
mvwaddnwstr curs_addwstr(3)
mvwaddstr curs_addstr(3)
mvwaddwstr curs_addwstr(3)
mvwchgat curs_attr(3)
mvwdelch curs_delch(3)
mvwget_wch curs_get_wch(3)
mvwget_wstr curs_get_wstr(3)
mvwgetch curs_getch(3)
mvwgetn_wstr curs_get_wstr(3)
mvwgetnstr curs_getstr(3)
mvwgetstr curs_getstr(3)
mvwhline curs_border(3)
mvwhline_set curs_border_set(3)
mvwin curs_window(3)
mvwin_wch curs_in_wch(3)
mvwin_wchnstr curs_in_wchstr(3)
mvwin_wchstr curs_in_wchstr(3)
mvwinch curs_inch(3)
mvwinchnstr curs_inchstr(3)
mvwinchstr curs_inchstr(3)
mvwinnstr curs_instr(3)
mvwinnwstr curs_inwstr(3)
mvwins_nwstr curs_ins_wstr(3)
mvwins_wch curs_ins_wch(3)
mvwins_wstr curs_ins_wstr(3)
mvwinsch curs_insch(3)
mvwinsnstr curs_insstr(3)
mvwinsstr curs_insstr(3)
mvwinstr curs_instr(3)
mvwinwstr curs_inwstr(3)
mvwprintw curs_printw(3)
mvwscanw curs_scanw(3)
mvwvline curs_border(3)
mvwvline_set curs_border_set(3)
napms curs_kernel(3)
newpad curs_pad(3)
newterm curs_initscr(3)
newwin curs_window(3)
nl curs_outopts(3)
nocbreak curs_inopts(3)
nodelay curs_inopts(3)
noecho curs_inopts(3)
nonl curs_outopts(3)
noqiflush curs_inopts(3)
noraw curs_inopts(3)
notimeout curs_inopts(3)
overlay curs_overlay(3)
overwrite curs_overlay(3)
pair_content curs_color(3)
pechochar curs_pad(3)
pnoutrefresh curs_pad(3)
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prefresh curs_pad(3)
printw curs_printw(3)
putp curs_terminfo(3)
putwin curs_util(3)
qiflush curs_inopts(3)
raw curs_inopts(3)
redrawwin curs_refresh(3)
refresh curs_refresh(3)
reset_prog_mode curs_kernel(3)
reset_shell_mode curs_kernel(3)
resetty curs_kernel(3)
resizeterm resizeterm(3)*
restartterm curs_terminfo(3)
ripoffline curs_kernel(3)
savetty curs_kernel(3)
scanw curs_scanw(3)
scr_dump curs_scr_dump(3)
scr_init curs_scr_dump(3)
scr_restore curs_scr_dump(3)
scr_set curs_scr_dump(3)
scrl curs_scroll(3)
scroll curs_scroll(3)
scrollok curs_outopts(3)
set_curterm curs_terminfo(3)
set_term curs_initscr(3)
setcchar curs_getcchar(3)
setscrreg curs_outopts(3)
setsyx curs_kernel(3)
setterm curs_terminfo(3)
setupterm curs_terminfo(3)
slk_attr curs_slk(3)*
slk_attr_off curs_slk(3)
slk_attr_on curs_slk(3)
slk_attr_set curs_slk(3)
slk_attroff curs_slk(3)
slk_attron curs_slk(3)
slk_attrset curs_slk(3)
slk_clear curs_slk(3)
slk_color curs_slk(3)
slk_init curs_slk(3)
slk_label curs_slk(3)
slk_noutrefresh curs_slk(3)
slk_refresh curs_slk(3)
slk_restore curs_slk(3)
slk_set curs_slk(3)
slk_touch curs_slk(3)
standend curs_attr(3)
standout curs_attr(3)
start_color curs_color(3)
subpad curs_pad(3)
subwin curs_window(3)
syncok curs_window(3)
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term_attrs curs_termattrs(3)
termattrs curs_termattrs(3)
termname curs_termattrs(3)
tgetent curs_termcap(3)
tgetflag curs_termcap(3)
tgetnum curs_termcap(3)
tgetstr curs_termcap(3)
tgoto curs_termcap(3)
tigetflag curs_terminfo(3)
tigetnum curs_terminfo(3)
tigetstr curs_terminfo(3)
timeout curs_inopts(3)
touchline curs_touch(3)
touchwin curs_touch(3)
tparm curs_terminfo(3)
tputs curs_termcap(3)
tputs curs_terminfo(3)
trace curs_trace(3)*
typeahead curs_inopts(3)
unctrl curs_util(3)
unget_wch curs_get_wch(3)
ungetch curs_getch(3)
ungetmouse curs_mouse(3)*
untouchwin curs_touch(3)
use_default_colors default_colors(3)*
use_env curs_util(3)
use_extended_names curs_extend(3)*
vid_attr curs_terminfo(3)
vid_puts curs_terminfo(3)
vidattr curs_terminfo(3)
vidputs curs_terminfo(3)
vline curs_border(3)
vline_set curs_border_set(3)
vw_printw curs_printw(3)
vw_scanw curs_scanw(3)
vwprintw curs_printw(3)
vwscanw curs_scanw(3)
wadd_wch curs_add_wch(3)
wadd_wchnstr curs_add_wchstr(3)
wadd_wchstr curs_add_wchstr(3)
waddch curs_addch(3)
waddchnstr curs_addchstr(3)
waddchstr curs_addchstr(3)
waddnstr curs_addstr(3)
waddnwstr curs_addwstr(3)
waddstr curs_addstr(3)
waddwstr curs_addwstr(3)
wattr_get curs_attr(3)
wattr_off curs_attr(3)
wattr_on curs_attr(3)
wattr_set curs_attr(3)
wattroff curs_attr(3)
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wattron curs_attr(3)
wattrset curs_attr(3)
wbkgd curs_bkgd(3)
wbkgdset curs_bkgd(3)
wbkgrnd curs_bkgrnd(3)
wbkgrndset curs_bkgrnd(3)
wborder curs_border(3)
wborder_set curs_border_set(3)
wchgat curs_attr(3)
wclear curs_clear(3)
wclrtobot curs_clear(3)
wclrtoeol curs_clear(3)
wcolor_set curs_attr(3)
wcursyncup curs_window(3)
wdelch curs_delch(3)
wdeleteln curs_deleteln(3)
wecho_wchar curs_add_wch(3)
wechochar curs_addch(3)
wenclose curs_mouse(3)*
werase curs_clear(3)
wget_wch curs_get_wch(3)
wget_wstr curs_get_wstr(3)
wgetbkgrnd curs_bkgrnd(3)
wgetch curs_getch(3)
wgetn_wstr curs_get_wstr(3)
wgetnstr curs_getstr(3)
wgetstr curs_getstr(3)
whline curs_border(3)
whline_set curs_border_set(3)
win_wch curs_in_wch(3)
win_wchnstr curs_in_wchstr(3)
win_wchstr curs_in_wchstr(3)
winch curs_inch(3)
winchnstr curs_inchstr(3)
winchstr curs_inchstr(3)
winnstr curs_instr(3)
winnwstr curs_inwstr(3)
wins_nwstr curs_ins_wstr(3)
wins_wch curs_ins_wch(3)
wins_wstr curs_ins_wstr(3)
winsch curs_insch(3)
winsdelln curs_deleteln(3)
winsertln curs_deleteln(3)
winsnstr curs_insstr(3)
winsstr curs_insstr(3)
winstr curs_instr(3)
winwstr curs_inwstr(3)
wmouse_trafo curs_mouse(3)*
wmove curs_move(3)
wnoutrefresh curs_refresh(3)
wprintw curs_printw(3)
wredrawln curs_refresh(3)
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wrefresh curs_refresh(3)
wresize wresize(3)*
wscanw curs_scanw(3)
wscrl curs_scroll(3)
wsetscrreg curs_outopts(3)
wstandend curs_attr(3)
wstandout curs_attr(3)
wsyncdown curs_window(3)
wsyncup curs_window(3)
wtimeout curs_inopts(3)
wtouchln curs_touch(3)
wunctrl curs_util(3)
wvline curs_border(3)
wvline_set curs_border_set(3)
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.
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).
Routines that return pointers return NULL on error.
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.
BAUDRATE
The debugging library checks this environment symbol
when the application has redirected output to a file.
The symbol's numeric value is used for the baudrate. If
no value is found, ncurses uses 9600. This allows tes-
ters to construct repeatable test-cases that take into
account costs that depend on baudrate.
CC When set, change occurrences of the command_character
(i.e., the cmdch capability) of the loaded terminfo
entries to the value of this symbol. Very few terminfo
entries provide this feature.
COLUMNS
Specify the width of the screen in characters. Applica-
tions 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
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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 (including system calls) to determine the
screen size.
ESCDELAY
Specifies the total time, in milliseconds, for which
ncurses will await a character sequence, e.g., a func-
tion 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 charac-
ter sequences received from the xterm. If your applica-
tion 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 implemen-
tation 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.
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HOME Tells ncurses where your home directory is. That is
where it may read and write auxiliary terminal descrip-
tions:
$HOME/.termcap
$HOME/.terminfo
LINES
Like COLUMNS, specify the height of the screen in char-
acters. See COLUMNS for a detailed description.
MOUSE_BUTTONS_123
This applies only to the OS/2 EMX port. It specifies
the order of buttons on the mouse. OS/2 numbers a 3-
button mouse inconsistently from other platforms:
1 = left
2 = right
3 = middle.
This symbol lets you customize the mouse. The symbol
must be three numeric digits 1-3 in any order, e.g.,
123 or 321. If it is not specified, ncurses uses 132.
NCURSES_ASSUMED_COLORS
Override the compiled-in assumption that the terminal's
default colors are white-on-black (see
assume_default_colors(3)). You may set the foreground
and background color values with this environment vari-
able 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_NO_PADDING
Most of the terminal descriptions in the terminfo data-
base 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 lim-
itations. The chief limitation of a hardware terminal
from the standpoint of your application is the manage-
ment of dataflow, i.e., timing. Unless a hardware ter-
minal 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.
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As a result, many terminal descriptions (including the
vt100) have delay times embedded. You may wish to use
these descriptions, but not want to pay the performance
penalty.
Set the NCURSES_NO_PADDING symbol to disable all but
mandatory padding. Mandatory padding is used as a part
of special control sequences such as flash.
NCURSES_NO_SETBUF
Normally ncurses enables buffered output during termi-
nal initialization. This is done (as in SVr4 curses)
for performance reasons. For testing purposes, both of
ncurses and certain applications, this feature is made
optional. Setting the NCURSES_NO_SETBUF variable dis-
ables output buffering, leaving the output in the ori-
ginal (usually line buffered) mode.
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.
NCURSES_TRACE
During initialization, the ncurses debugging library
checks the NCURSES_TRACE symbol. If it is defined, to a
numeric value, ncurses calls the trace function, using
that value as the argument.
The argument values, which are defined in curses.h,
provide several types of information. When running with
traces enabled, your application will write the file
trace to the current directory.
TERM Denotes your terminal type. Each terminal type is dis-
tinct, though many are similar.
TERMCAP
If the ncurses library has been configured with termcap
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support, ncurses will check for a terminal's descrip-
tion in termcap form if it is not available in the ter-
minfo database.
The TERMCAP symbol contains either a terminal descrip-
tion (with newlines stripped out), or a file name tel-
ling where the information denoted by the TERM symbol
exists. In either case, setting it directs ncurses to
ignore the usual place for this information, e.g.,
/etc/termcap.
TERMINFO
Overrides the directory in which ncurses searches for
your terminal description. This is the simplest, but
not the only way to change the list of directories. The
complete list of directories in order follows:
- the last directory to which ncurses wrote, if any,
is searched first
- the directory specified by the TERMINFO symbol
- $HOME/.terminfo
- directories listed in the TERMINFO_DIRS symbol
- one or more directories whose names are configured
and compiled into the ncurses library, e.g.,
/usr/share/terminfo
TERMINFO_DIRS
Specifies a list of directories to search for terminal
descriptions. The list is separated by colons (i.e.,
":") on Unix, semicolons on OS/2 EMX. All of the termi-
nal descriptions are in terminfo form, which makes a
subdirectory named for the first letter of the terminal
names therein.
TERMPATH
If TERMCAP does not hold a file name then ncurses
checks the TERMPATH symbol. This is a list of filenames
separated by spaces or colons (i.e., ":") on Unix,
semicolons on OS/2 EMX. If the TERMPATH symbol is not
set, ncurses looks in the files /etc/termcap,
/usr/share/misc/termcap and $HOME/.termcap, in that
order.
The library may be configured to disregard the following
variables when the current user is the superuser (root), or
if the application uses setuid or setgid permissions: $TER-
MINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.
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/usr/share/tabset
directory containing initialization files for the ter-
minal capability database /usr/share/terminfo terminal
capability database
terminfo(5) and related pages whose names begin "curs_" for
detailed routine descriptions.
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 recom-
mended, as it essentially includes an entire termcap com-
piler in the ncurses startup code, at significant cost in
core and startup cycles.
The ncurses library includes facilities for capturing mouse
events on certain terminals (including xterm). See the
curs_mouse(3) 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(3) and wresize(3) 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(3) key_defined(3), and keyok(3) manual pages
for details.
The ncurses library can exploit the capabilities of termi-
nals which implement the ISO-6429 SGR 39 and SGR 49 con-
trols, which allow an application to reset the terminal to
its original foreground and background colors. From the
users' perspective, the application is able to draw colored
text on a background whose color is set independently, pro-
viding better control over color contrasts. See the
default_colors(3) manual page for details.
The ncurses library includes a function for directing appli-
cation output to a printer attached to the terminal device.
See the curs_print(3) manual page for details.
The ncurses library is intended to be BASE-level conformant
with the XSI Curses standard. The EXTENDED XSI Curses func-
tionality (including color support) is supported.
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A small number of local differences (that is, individual
differences between the XSI Curses and ncurses calls) are
described in PORTABILITY sections of the library man pages.
The routine has_key is not part of XPG4, nor is it present
in SVr4. See the curs_getch(3) manual page for details.
The routine slk_attr is not part of XPG4, nor is it present
in SVr4. See the curs_slk(3) 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 curs_mouse(3)
manual page for details.
The routine mcprint was not present in any previous curses
implementation. See the curs_print(3) manual page for
details.
The routine wresize is not part of XPG4, nor is it present
in SVr4. See the wresize(3) manual page for details.
In historic curses versions, delays embedded in the capabil-
ities cr, ind, cub1, ff and tab activated corresponding
delay bits in the UNIX tty driver. In this implementation,
all padding is done by NUL sends. This method is slightly
more expensive, but narrows the interface to the UNIX kernel
significantly and increases the package's portability
correspondingly.
The header file <curses.h> automatically includes the header
files <stdio.h> and <unctrl.h>.
If standard output from a ncurses program is re-directed to
something which is not a tty, screen updates will be
directed to standard error. This was an undocumented
feature of AT&T System V Release 3 curses.
Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey. Based
on pcurses by Pavel Curtis.
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