https://invisible-island.net/ncurses/man/
ncurses(3x) Library calls ncurses(3x)
ncurses - character-cell terminal interface with optimized output
#include <curses.h>
The "new curses" library offers the programmer a terminal-independent
means of reading keyboard and mouse input and updating character-cell
terminals with output optimized to minimize screen updates. ncurses
replaces the curses libraries from System V Release 4 Unix ("SVr4") and
4.4BSD Unix, the development of which ceased in the 1990s. This
describes ncurses version 6.4 (patch 20240413).
ncurses permits control of the terminal screen's contents; abstraction
and subdivision thereof with windows and pads; the reading of terminal
input; control of terminal input and output options; environment query
routines; color manipulation; the definition and use of soft label
keys; terminfo capability access; a termcap compatibility interface;
and an abstraction of the system's API for manipulating the terminal
(such as termios(3)).
ncurses implements the standard interface described by X/Open Curses
Issue 7. In many behavioral details not standardized by X/Open,
ncurses emulates the curses library of SVr4 and provides numerous
useful extensions.
ncurses man pages employ several sections to clarify matters of usage
and interoperability with other curses implementations.
o "NOTES" describes issues and caveats of which any user of the
ncurses API should be aware, such as limitations on the size of an
underlying integral type or the availability of a preprocessor
macro exclusive of a function definition (which prevents its
address from being taken). This section also describes
implementation details that will be significant to the programmer
but which are not standardized.
o "EXTENSIONS" presents ncurses innovations beyond the X/Open Curses
standard and/or the SVr4 curses implementation. They are termed
extensions to indicate that they cannot be implemented solely by
using the library API, but require access to the library's internal
state.
o "PORTABILITY" discusses matters (beyond the exercise of extensions)
that should be considered when writing to a curses standard, or for
multiple implementations.
o "HISTORY" examines points of detail in ncurses and other curses
implementations over the decades of their development, particularly
where precedent or inertia have frustrated better design (and, in a
few cases, where such inertia has been overcome).
A curses application must be linked with the library; use the -lncurses
option to your compiler or linker. A debugging version of the library
may be available; if so, link with it using -lncurses_g. (Your system
integrator may have installed these libraries such that you can use the
options -lcurses and -lcurses_g, respectively.) The ncurses_g library
generates trace logs (in a file called trace in the current directory)
that describe ncurses actions. See section "ALTERNATE CONFIGURATIONS"
below.
A curses application uses information from the system locale;
setlocale(3) prepares it for curses library calls.
setlocale(LC_ALL, "");
If the locale is not thus initialized, the library assumes that
characters are printable as in ISO 8859-1, to work with certain legacy
programs. You should initialize the locale; do not expect consistent
behavior from the library when the locale has not been set up.
initscr(3x) or newterm(3x) must be called to initialize curses before
use of any functions that deal with windows and screens.
To get character-at-a-time input without echoing--most interactive,
screen-oriented programs want this--use the following sequence.
initscr(); cbreak(); noecho();
Most applications perform further setup as follows.
intrflush(stdscr, FALSE);
keypad(stdscr, TRUE);
A curses program then often enters an event loop of some sort. Call
endwin(3x) before exiting.
A curses library abstracts the terminal screen by representing all or
part of it as a WINDOW data structure. A window is a rectangular grid
of character cells, addressed by row and column coordinates (y, x),
with the upper left corner as (0, 0). A window called stdscr, the same
size as the terminal screen, is always available. Create others with
newwin(3x).
A curses library does not manage overlapping windows (but see below).
You can either use stdscr to manage one screen-filling window, or tile
the screen into non-overlapping windows and not use stdscr at all.
Mixing the two approaches will result in unpredictable and undesired
effects.
Functions permit manipulation of a window and the cursor identifying
the cell within it at which the next output operation will occur.
Among those, the most basic are move(3x) and addch(3x): these place the
cursor and write a character to stdscr, respectively.
Frequent changes to the terminal screen can cause unpleasant flicker or
inefficient use of the communication channel to the device, so the
library does not generally update it automatically. Therefore, after
using curses functions to accumulate a set of desired updates that make
sense to present together, call refresh(3x) to tell the library to make
the user's screen look like stdscr. The library optimizes its output
by computing a minimal number of operations to mutate the screen from
its state at the previous refresh to the new one. Effective
optimization demands accurate information about the terminal device:
the management of such information is the province of the terminfo(3x)
API, a feature of every standard curses implementation.
Special windows called pads may also be manipulated. These are windows
that are not constrained to the size of the terminal screen and whose
contents need not be completely displayed. See curs_pad(3x).
In addition to drawing characters on the screen, rendering 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. See curs_attr(3x).
curses predefines constants for a small set of forms-drawing graphics
corresponding to the DEC Alternate Character Set (ACS), a feature of
VT100 and other terminals. See waddch(3x).
curses is implemented using the operating system's terminal driver;
keystroke events are received not as scan codes but as byte sequences.
Graphical keycaps (alphanumeric and punctuation keys, and the space)
appear as-is. Everything else, including the tab, enter/return,
keypad, arrow, and function keys, appears as a control character or a
multibyte escape sequence. curses translates these into unique key
codes. See getch(3x).
ncurses provides reimplementations of the SVr4 panel(3x), form(3x), and
menu(3x) libraries to ease construction of user interfaces with curses.
The selection of an appropriate value of TERM in the process
environment is essential to correct curses and terminfo library
operation. A well-configured system selects a correct TERM value
automatically; tset(1) may assist with troubleshooting exotic
situations.
If you change the terminal type, export the TERM environment variable
in the shell, then run tset(1) or the "tput init" command. See
subsection "Tabs and Initialization" of terminfo(5).
If the environment variables LINES and COLUMNS are set, or if the
curses program is executing in a graphical windowing environment, the
information obtained thence overrides that obtained by terminfo. An
ncurses extension supports resizable terminals; see wresize(3x).
If the environment variable TERMINFO is defined, a curses program
checks first for a terminal type description in the location it
identifies. TERMINFO is useful for developing experimental type
descriptions or when write permission to /usr/share/terminfo is not
available.
See section "ENVIRONMENT" below.
curses offers many functions in variant forms using a regular set of
alternatives to the name of an elemental one. Those prefixed with "w"
require a WINDOW pointer argument; those with a "mv" prefix first
perform cursor movement using wmove(3x); a "mvw" prefix indicates both.
The "w" function is typically the elemental one; the removal of this
prefix usually indicates operation on stdscr.
Four functions prefixed with "p" require a pad argument.
In function synopses, ncurses man pages apply the following names to
parameters.
bf bool (TRUE or FALSE)
win pointer to a WINDOW
pad pointer to a WINDOW that is a pad
This manual page describes functions that appear in any configuration
of the library. There are two common configurations; see section
"ALTERNATE CONFIGURATIONS" below.
ncurses is the library in its "non-wide" configuration, handling only
eight-bit characters. It stores a character combined with
attributes in a chtype datum, which is often an alias of int.
Attributes alone (with no corresponding character) can be
stored in variables of chtype or attr_t type. In either
case, they are represented as an integral bit mask.
Each cell of a WINDOW is stored as a chtype.
ncursesw is the library in its "wide" configuration, which handles
character encodings requiring a larger data type than char (a
byte-sized type) can represent. It adds about one third more
calls using additional data types that can store such
multibyte characters.
cchar_t corresponds to the non-wide configuration's chtype.
It always a structure type, because it stores more
data than fit into a standard scalar type. A
character code may not be representable as a char,
and moreover more than one character may occupy a
cell (as with accent marks and other diacritics).
Each character is of type wchar_t; a complex
character contains one spacing character and zero or
more non-spacing characters (see below). Attributes
and color data are stored in separate fields of the
structure, not combined as in chtype.
Each cell of a WINDOW is stored as a cchar_t.
setcchar(3x) and getcchar(3x) store and retrieve cchar_t
data. The wide library API of ncurses depends on two data
types standardized by ISO C95.
wchar_t stores a wide character. Like chtype, it may be an
alias of int. Depending on the character encoding,
a wide character may be spacing, meaning that it
occupies a character cell by itself and typically
accompanies cursor advancement, or non-spacing,
meaning that it occupies the same cell as a spacing
character, is often regarded as a "modifier" of the
base glyph with which it combines, and typically
does not advance the cursor.
wint_t can store a wchar_t or the constant WEOF,
analogously to the int-sized character manipulation
functions of ISO C and its constant EOF.
The wide library provides additional functions that
complement those in the non-wide library where the size of
the underlying character type is significant. A somewhat
regular naming convention relates many of the wide variants
to their non-wide counterparts; where a non-wide function
name contains "ch" or "str", prefix it with "_w" to obtain
the wide counterpart. For example, waddch becomes wadd_wch.
(Exceptions that add only "w" comprise addwstr, inwstr, and
their variants.)
This convention is inapplicable to some non-wide function
names, so other transformations are used for the wide
configuration: the window background management function
"bkgd" becomes "bkgrnd"; the window border-drawing and
-clearing functions are suffixed with "_set"; and character
attribute manipulation functions like "attron" become
"attr_on".
The following table lists the curses functions provided in the non-wide
and wide APIs and the corresponding man pages that describe them.
Those flagged with "*" are ncurses-specific, neither described by
X/Open Curses nor present in SVr4.
curses Function Name Man Page
---------------------------------------------
COLOR_PAIR curs_color(3x)
PAIR_NUMBER curs_color(3x)
add_wch curs_add_wch(3x)
add_wchnstr curs_add_wchstr(3x)
add_wchstr curs_add_wchstr(3x)
addch curs_addch(3x)
addchnstr curs_addchstr(3x)
addchstr curs_addchstr(3x)
addnstr curs_addstr(3x)
addnwstr curs_addwstr(3x)
addstr curs_addstr(3x)
addwstr curs_addwstr(3x)
alloc_pair new_pair(3x)*
assume_default_colors default_colors(3x)*
attr_get curs_attr(3x)
attr_off curs_attr(3x)
attr_on curs_attr(3x)
attr_set curs_attr(3x)
attroff curs_attr(3x)
attron curs_attr(3x)
attrset curs_attr(3x)
baudrate curs_termattrs(3x)
beep curs_beep(3x)
bkgd curs_bkgd(3x)
bkgdset curs_bkgd(3x)
bkgrnd curs_bkgrnd(3x)
bkgrndset curs_bkgrnd(3x)
border curs_border(3x)
border_set curs_border_set(3x)
box curs_border(3x)
box_set curs_border_set(3x)
can_change_color curs_color(3x)
cbreak curs_inopts(3x)
chgat curs_attr(3x)
clear curs_clear(3x)
clearok curs_outopts(3x)
clrtobot curs_clear(3x)
clrtoeol curs_clear(3x)
color_content curs_color(3x)
color_set curs_attr(3x)
copywin curs_overlay(3x)
curs_set curs_kernel(3x)
curses_trace curs_trace(3x)*
curses_version curs_extend(3x)*
def_prog_mode curs_kernel(3x)
def_shell_mode curs_kernel(3x)
define_key define_key(3x)*
del_curterm curs_terminfo(3x)
delay_output curs_util(3x)
delch curs_delch(3x)
deleteln curs_deleteln(3x)
delscreen curs_initscr(3x)
delwin curs_window(3x)
derwin curs_window(3x)
doupdate curs_refresh(3x)
dupwin curs_window(3x)
echo curs_inopts(3x)
echo_wchar curs_add_wch(3x)
echochar curs_addch(3x)
endwin curs_initscr(3x)
erase curs_clear(3x)
erasechar curs_termattrs(3x)
erasewchar curs_termattrs(3x)
exit_curses curs_memleaks(3x)*
exit_terminfo curs_memleaks(3x)*
extended_color_content curs_color(3x)*
extended_pair_content curs_color(3x)*
extended_slk_color curs_slk(3x)*
filter curs_util(3x)
find_pair new_pair(3x)*
flash curs_beep(3x)
flushinp curs_util(3x)
free_pair new_pair(3x)*
get_escdelay curs_threads(3x)*
get_wch curs_get_wch(3x)
get_wstr curs_get_wstr(3x)
getattrs curs_attr(3x)
getbegx curs_legacy(3x)*
getbegy curs_legacy(3x)*
getbegyx curs_getyx(3x)
getbkgd curs_bkgd(3x)
getbkgrnd curs_bkgrnd(3x)
getcchar curs_getcchar(3x)
getch curs_getch(3x)
getcurx curs_legacy(3x)*
getcury curs_legacy(3x)*
getmaxx curs_legacy(3x)*
getmaxy curs_legacy(3x)*
getmaxyx curs_getyx(3x)
getmouse curs_mouse(3x)*
getn_wstr curs_get_wstr(3x)
getnstr curs_getstr(3x)
getparx curs_legacy(3x)*
getpary curs_legacy(3x)*
getparyx curs_getyx(3x)
getstr curs_getstr(3x)
getsyx curs_kernel(3x)
getwin curs_util(3x)
getyx curs_getyx(3x)
halfdelay curs_inopts(3x)
has_colors curs_color(3x)
has_ic curs_termattrs(3x)
has_il curs_termattrs(3x)
has_key curs_getch(3x)*
has_mouse curs_mouse(3x)*
hline curs_border(3x)
hline_set curs_border_set(3x)
idcok curs_outopts(3x)
idlok curs_outopts(3x)
immedok curs_outopts(3x)
in_wch curs_in_wch(3x)
in_wchnstr curs_in_wchstr(3x)
in_wchstr curs_in_wchstr(3x)
inch curs_inch(3x)
inchnstr curs_inchstr(3x)
inchstr curs_inchstr(3x)
init_color curs_color(3x)
init_extended_color curs_color(3x)*
init_extended_pair curs_color(3x)*
init_pair curs_color(3x)
initscr curs_initscr(3x)
innstr curs_instr(3x)
innwstr curs_inwstr(3x)
ins_nwstr curs_ins_wstr(3x)
ins_wch curs_ins_wch(3x)
ins_wstr curs_ins_wstr(3x)
insch curs_insch(3x)
insdelln curs_deleteln(3x)
insertln curs_deleteln(3x)
insnstr curs_insstr(3x)
insstr curs_insstr(3x)
instr curs_instr(3x)
intrflush curs_inopts(3x)
inwstr curs_inwstr(3x)
is_cbreak curs_inopts(3x)*
is_cleared curs_opaque(3x)*
is_echo curs_inopts(3x)*
is_idcok curs_opaque(3x)*
is_idlok curs_opaque(3x)*
is_immedok curs_opaque(3x)*
is_keypad curs_opaque(3x)*
is_leaveok curs_opaque(3x)*
is_linetouched curs_touch(3x)
is_nl curs_inopts(3x)*
is_nodelay curs_opaque(3x)*
is_notimeout curs_opaque(3x)*
is_pad curs_opaque(3x)*
is_raw curs_inopts(3x)*
is_scrollok curs_opaque(3x)*
is_subwin curs_opaque(3x)*
is_syncok curs_opaque(3x)*
is_term_resized resizeterm(3x)*
is_wintouched curs_touch(3x)
isendwin curs_initscr(3x)
key_defined key_defined(3x)*
key_name curs_util(3x)
keybound keybound(3x)*
keyname curs_util(3x)
keyok keyok(3x)*
keypad curs_inopts(3x)
killchar curs_termattrs(3x)
killwchar curs_termattrs(3x)
leaveok curs_outopts(3x)
longname curs_termattrs(3x)
mcprint curs_print(3x)*
meta curs_inopts(3x)
mouse_trafo curs_mouse(3x)*
mouseinterval curs_mouse(3x)*
mousemask curs_mouse(3x)*
move curs_move(3x)
mvadd_wch curs_add_wch(3x)
mvadd_wchnstr curs_add_wchstr(3x)
mvadd_wchstr curs_add_wchstr(3x)
mvaddch curs_addch(3x)
mvaddchnstr curs_addchstr(3x)
mvaddchstr curs_addchstr(3x)
mvaddnstr curs_addstr(3x)
mvaddnwstr curs_addwstr(3x)
mvaddstr curs_addstr(3x)
mvaddwstr curs_addwstr(3x)
mvchgat curs_attr(3x)
mvcur curs_terminfo(3x)
mvdelch curs_delch(3x)
mvderwin curs_window(3x)
mvget_wch curs_get_wch(3x)
mvget_wstr curs_get_wstr(3x)
mvgetch curs_getch(3x)
mvgetn_wstr curs_get_wstr(3x)
mvgetnstr curs_getstr(3x)
mvgetstr curs_getstr(3x)
mvhline curs_border(3x)
mvhline_set curs_border_set(3x)
mvin_wch curs_in_wch(3x)
mvin_wchnstr curs_in_wchstr(3x)
mvin_wchstr curs_in_wchstr(3x)
mvinch curs_inch(3x)
mvinchnstr curs_inchstr(3x)
mvinchstr curs_inchstr(3x)
mvinnstr curs_instr(3x)
mvinnwstr curs_inwstr(3x)
mvins_nwstr curs_ins_wstr(3x)
mvins_wch curs_ins_wch(3x)
mvins_wstr curs_ins_wstr(3x)
mvinsch curs_insch(3x)
mvinsnstr curs_insstr(3x)
mvinsstr curs_insstr(3x)
mvinstr curs_instr(3x)
mvinwstr curs_inwstr(3x)
mvprintw curs_printw(3x)
mvscanw curs_scanw(3x)
mvvline curs_border(3x)
mvvline_set curs_border_set(3x)
mvwadd_wch curs_add_wch(3x)
mvwadd_wchnstr curs_add_wchstr(3x)
mvwadd_wchstr curs_add_wchstr(3x)
mvwaddch curs_addch(3x)
mvwaddchnstr curs_addchstr(3x)
mvwaddchstr curs_addchstr(3x)
mvwaddnstr curs_addstr(3x)
mvwaddnwstr curs_addwstr(3x)
mvwaddstr curs_addstr(3x)
mvwaddwstr curs_addwstr(3x)
mvwchgat curs_attr(3x)
mvwdelch curs_delch(3x)
mvwget_wch curs_get_wch(3x)
mvwget_wstr curs_get_wstr(3x)
mvwgetch curs_getch(3x)
mvwgetn_wstr curs_get_wstr(3x)
mvwgetnstr curs_getstr(3x)
mvwgetstr curs_getstr(3x)
mvwhline curs_border(3x)
mvwhline_set curs_border_set(3x)
mvwin curs_window(3x)
mvwin_wch curs_in_wch(3x)
mvwin_wchnstr curs_in_wchstr(3x)
mvwin_wchstr curs_in_wchstr(3x)
mvwinch curs_inch(3x)
mvwinchnstr curs_inchstr(3x)
mvwinchstr curs_inchstr(3x)
mvwinnstr curs_instr(3x)
mvwinnwstr curs_inwstr(3x)
mvwins_nwstr curs_ins_wstr(3x)
mvwins_wch curs_ins_wch(3x)
mvwins_wstr curs_ins_wstr(3x)
mvwinsch curs_insch(3x)
mvwinsnstr curs_insstr(3x)
mvwinsstr curs_insstr(3x)
mvwinstr curs_instr(3x)
mvwinwstr curs_inwstr(3x)
mvwprintw curs_printw(3x)
mvwscanw curs_scanw(3x)
mvwvline curs_border(3x)
mvwvline_set curs_border_set(3x)
napms curs_kernel(3x)
newpad curs_pad(3x)
newterm curs_initscr(3x)
newwin curs_window(3x)
nl curs_inopts(3x)
nocbreak curs_inopts(3x)
nodelay curs_inopts(3x)
noecho curs_inopts(3x)
nofilter curs_util(3x)*
nonl curs_inopts(3x)
noqiflush curs_inopts(3x)
noraw curs_inopts(3x)
notimeout curs_inopts(3x)
overlay curs_overlay(3x)
overwrite curs_overlay(3x)
pair_content curs_color(3x)
pecho_wchar curs_pad(3x)
pechochar curs_pad(3x)
pnoutrefresh curs_pad(3x)
prefresh curs_pad(3x)
printw curs_printw(3x)
putp curs_terminfo(3x)
putwin curs_util(3x)
qiflush curs_inopts(3x)
raw curs_inopts(3x)
redrawwin curs_refresh(3x)
refresh curs_refresh(3x)
reset_color_pairs curs_color(3x)*
reset_prog_mode curs_kernel(3x)
reset_shell_mode curs_kernel(3x)
resetty curs_kernel(3x)
resize_term resizeterm(3x)*
resizeterm resizeterm(3x)*
restartterm curs_terminfo(3x)
ripoffline curs_kernel(3x)
savetty curs_kernel(3x)
scanw curs_scanw(3x)
scr_dump curs_scr_dump(3x)
scr_init curs_scr_dump(3x)
scr_restore curs_scr_dump(3x)
scr_set curs_scr_dump(3x)
scrl curs_scroll(3x)
scroll curs_scroll(3x)
scrollok curs_outopts(3x)
set_curterm curs_terminfo(3x)
set_escdelay curs_threads(3x)*
set_tabsize curs_threads(3x)*
set_term curs_initscr(3x)
setcchar curs_getcchar(3x)
setscrreg curs_outopts(3x)
setsyx curs_kernel(3x)
setupterm curs_terminfo(3x)
slk_attr curs_slk(3x)*
slk_attr_off curs_slk(3x)
slk_attr_on curs_slk(3x)
slk_attr_set curs_slk(3x)
slk_attroff curs_slk(3x)
slk_attron curs_slk(3x)
slk_attrset curs_slk(3x)
slk_clear curs_slk(3x)
slk_color curs_slk(3x)
slk_init curs_slk(3x)
slk_label curs_slk(3x)
slk_noutrefresh curs_slk(3x)
slk_refresh curs_slk(3x)
slk_restore curs_slk(3x)
slk_set curs_slk(3x)
slk_touch curs_slk(3x)
slk_wset curs_slk(3x)
standend curs_attr(3x)
standout curs_attr(3x)
start_color curs_color(3x)
subpad curs_pad(3x)
subwin curs_window(3x)
syncok curs_window(3x)
term_attrs curs_termattrs(3x)
termattrs curs_termattrs(3x)
termname curs_termattrs(3x)
tgetent curs_termcap(3x)
tgetflag curs_termcap(3x)
tgetnum curs_termcap(3x)
tgetstr curs_termcap(3x)
tgoto curs_termcap(3x)
tigetflag curs_terminfo(3x)
tigetnum curs_terminfo(3x)
tigetstr curs_terminfo(3x)
timeout curs_inopts(3x)
tiparm curs_terminfo(3x)
tiparm_s curs_terminfo(3x)*
tiscan_s curs_terminfo(3x)*
touchline curs_touch(3x)
touchwin curs_touch(3x)
tparm curs_terminfo(3x)
tputs curs_termcap(3x)
tputs curs_terminfo(3x)
trace curs_trace(3x)*
typeahead curs_inopts(3x)
unctrl curs_util(3x)
unget_wch curs_get_wch(3x)
ungetch curs_getch(3x)
ungetmouse curs_mouse(3x)*
untouchwin curs_touch(3x)
use_default_colors default_colors(3x)*
use_env curs_util(3x)
use_extended_names curs_extend(3x)*
use_legacy_coding legacy_coding(3x)*
use_screen curs_threads(3x)*
use_tioctl curs_util(3x)*
use_window curs_threads(3x)*
vid_attr curs_terminfo(3x)
vid_puts curs_terminfo(3x)
vidattr curs_terminfo(3x)
vidputs curs_terminfo(3x)
vline curs_border(3x)
vline_set curs_border_set(3x)
vw_printw curs_printw(3x)
vw_scanw curs_scanw(3x)
vwprintw curs_printw(3x)
vwscanw curs_scanw(3x)
wadd_wch curs_add_wch(3x)
wadd_wchnstr curs_add_wchstr(3x)
wadd_wchstr curs_add_wchstr(3x)
waddch curs_addch(3x)
waddchnstr curs_addchstr(3x)
waddchstr curs_addchstr(3x)
waddnstr curs_addstr(3x)
waddnwstr curs_addwstr(3x)
waddstr curs_addstr(3x)
waddwstr curs_addwstr(3x)
wattr_get curs_attr(3x)
wattr_off curs_attr(3x)
wattr_on curs_attr(3x)
wattr_set curs_attr(3x)
wattroff curs_attr(3x)
wattron curs_attr(3x)
wattrset curs_attr(3x)
wbkgd curs_bkgd(3x)
wbkgdset curs_bkgd(3x)
wbkgrnd curs_bkgrnd(3x)
wbkgrndset curs_bkgrnd(3x)
wborder curs_border(3x)
wborder_set curs_border_set(3x)
wchgat curs_attr(3x)
wclear curs_clear(3x)
wclrtobot curs_clear(3x)
wclrtoeol curs_clear(3x)
wcolor_set curs_attr(3x)
wcursyncup curs_window(3x)
wdelch curs_delch(3x)
wdeleteln curs_deleteln(3x)
wecho_wchar curs_add_wch(3x)
wechochar curs_addch(3x)
wenclose curs_mouse(3x)*
werase curs_clear(3x)
wget_wch curs_get_wch(3x)
wget_wstr curs_get_wstr(3x)
wgetbkgrnd curs_bkgrnd(3x)
wgetch curs_getch(3x)
wgetdelay curs_opaque(3x)*
wgetn_wstr curs_get_wstr(3x)
wgetnstr curs_getstr(3x)
wgetparent curs_opaque(3x)*
wgetscrreg curs_opaque(3x)*
wgetstr curs_getstr(3x)
whline curs_border(3x)
whline_set curs_border_set(3x)
win_wch curs_in_wch(3x)
win_wchnstr curs_in_wchstr(3x)
win_wchstr curs_in_wchstr(3x)
winch curs_inch(3x)
winchnstr curs_inchstr(3x)
winchstr curs_inchstr(3x)
winnstr curs_instr(3x)
winnwstr curs_inwstr(3x)
wins_nwstr curs_ins_wstr(3x)
wins_wch curs_ins_wch(3x)
wins_wstr curs_ins_wstr(3x)
winsch curs_insch(3x)
winsdelln curs_deleteln(3x)
winsertln curs_deleteln(3x)
winsnstr curs_insstr(3x)
winsstr curs_insstr(3x)
winstr curs_instr(3x)
winwstr curs_inwstr(3x)
wmouse_trafo curs_mouse(3x)*
wmove curs_move(3x)
wnoutrefresh curs_refresh(3x)
wprintw curs_printw(3x)
wredrawln curs_refresh(3x)
wrefresh curs_refresh(3x)
wresize wresize(3x)*
wscanw curs_scanw(3x)
wscrl curs_scroll(3x)
wsetscrreg curs_outopts(3x)
wstandend curs_attr(3x)
wstandout curs_attr(3x)
wsyncdown curs_window(3x)
wsyncup curs_window(3x)
wtimeout curs_inopts(3x)
wtouchln curs_touch(3x)
wunctrl curs_util(3x)
wvline curs_border(3x)
wvline_set curs_border_set(3x)
ncurses's screen-pointer extension adds additional functions
corresponding to many of the above, each with an "_sp" suffix; see
curs_sp_funcs(3x).
The availability of some extensions is configurable when ncurses is
compiled; see sections "ALTERNATE CONFIGURATIONS" and "EXTENSIONS"
below.
Unless otherwise noted, functions that return an integer return OK on
success and ERR on failure. Functions that return pointers return NULL
on failure. Typically, ncurses treats a null pointer passed as a
function parameter as a failure. Functions with a "mv" prefix first
perform cursor movement using wmove(3x) and fail if the position is
outside the window.
The following symbols from the process environment customize the
runtime behavior of ncurses applications. The library may be
configured to disregard the variables TERMINFO, TERMINFO_DIRS,
TERMPATH, and HOME, if the user is the superuser (root), or the
application uses setuid(2) or setgid(2).
The debugging library checks this variable when the application has
redirected output to a file. Its integral value is used for the baud
rate. If that value is absent or invalid, ncurses uses 9600. This
feature allows testers to construct repeatable test cases that take
into account optimization decisions that depend on baud rate.
When set, the command_character (cmdch) capability value of loaded
terminfo entries changes to the value of this variable. Very few term-
info entries provide this feature.
Because this name is also used in development environments to represent
the C compiler's name, ncurses ignores its value if it is not one
character in length.
This variable specifies 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 COLUMNS
is not defined and the terminal's screen size is not available from the
terminal driver, ncurses uses the size specified by the columns (cols)
capability of the terminal type's entry in the terminfo database, if
any.
It is important that your application use the correct screen size.
Automatic detection thereof is not always possible because an
application may be running on a host that does not honor NAWS
(Negotiations About Window Size) or as a different user ID than the
owner of the terminal device file. Setting COLUMNS and/or LINES
overrides the library's use of the screen size obtained from the
operating system.
The COLUMNS and LINES variables may be specified independently. This
property is useful to circumvent misfeatures of legacy terminal type
descriptions; xterm(1) descriptions specifying 65 lines were once
notorious. For best results, avoid specifying cols and lines
capability codes in terminfo descriptions of terminal emulators.
use_env(3x) can disable use of the process environment in determining
the screen size. use_tioctl(3x) can update COLUMNS and LINES to match
the screen size obtained from system calls or the terminal database.
For curses to distinguish the ESC character resulting from a user's
press of the "Escape" key on the input device from one beginning an
escape sequence (as commonly produced by function keys), it waits after
receiving the escape character to see if further characters are
available on the input stream within a short interval. A global
variable ESCDELAY stores this interval in milliseconds. The default
value of 1000 (one second) is adequate for most uses. This environment
variable overrides it.
The most common instance where you may wish to change this value is to
work with a remote host over a slow communication channel. If the host
running a curses application does not receive the characters of an
escape sequence in a timely manner, the library can interpret them as
multiple key stroke events.
xterm(1) mouse events are a form of escape sequence; therefore, if your
application makes heavy use of multiple-clicking, you may wish to
lengthen the default value because the delay applies to the composite
multi-click event as well as the individual clicks.
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.
If keypad(3x) is disabled for the curses window receiving input, a
program must disambiguate escape sequences itself.
ncurses may read and write auxiliary terminal descriptions in .termcap
and .terminfo files in the user's home directory.
This counterpart to COLUMNS specifies the height of the screen in
characters. The corresponding terminfo capability and code is lines.
See the description of the COLUMNS variable above.
(OS/2 EMX port only) OS/2 numbers a three-button mouse inconsistently
with other platforms, such that 1 is the left button, 2 the right, and
3 the middle. This variable customizes the mouse button numbering.
Its value must be three digits 1-3 in any order. By default, ncurses
assumes a numbering of "132".
If set, this variable overrides the ncurses library's compiled-in
assumption that the terminal's default colors are white on black; see
default_colors(3x). Set the foreground and background color values
with this environment variable by assigning it two integer values
separated by a comma, indicating foregound and background color
numbers, respectively.
For example, to tell ncurses not to assume anything about the colors,
use a value of "-1,-1". To make the default color scheme green on
black, use "2,0". ncurses accepts integral values from -1 up to the
value of the terminfo max_colors (colors) capability.
(MinGW port only) The Console2 program defectively handles the
Microsoft Console API call CreateConsoleScreenBuffer. Applications
that use it 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.
(Linux only) When ncurses is configured to use the GPM interface, this
variable may list one or more terminal names against which the TERM
variable (see below) is matched. An empty value disables the GPM
interface, using ncurses's built-in support for xterm(1) mouse
protocols instead. If the variable is absent, ncurses attempts to open
GPM if TERM contains "linux".
ncurses may use tab characters in cursor movement optimization. In
some cases, your terminal driver may not handle them properly. Set
this environment variable to any value to disable the feature. You can
also adjust your stty(1) settings to avoid the problem.
Many terminals store video attributes as a property of a character
cell, as curses does. Historically, some recorded changes in video
attributes as data that logically occupies character cells on the
display, switching attributes on or off, similarly to tags in a markup
language; these are termed "magic cookies", and must be subsequently
overprinted. If the terminfo entry for your terminal type does not
adequately describe its handling of magic cookies, set this variable to
any value to instruct ncurses to disable attributes entirely.
Most terminal type descriptions in the terminfo database detail
hardware devices. Many people use curses-based applications in
terminal emulator programs that run in a windowing environment. These
programs can duplicate all of the important features of a hardware
terminal, but often lack their limitations. Chief among these absent
drawbacks is the problem of data flow management; that is, limiting the
speed of communication to what the hardware could handle. Unless a
hardware terminal is interfaced into a terminal concentrator (which
does flow control), an application must manage flow control itself to
prevent overruns and data loss.
A solution that comes at no hardware cost is for an application to
pause after directing a terminal to execute an operation that it
performs slowly, such as clearing the display. Many terminal type
descriptions, including that for the VT100, embed delay specifications
in capabilities. You may wish to use these temrinal descriptions
without paying the performance penalty. Set NCURSES_NO_PADDING to any
value to disable all but mandatory padding. Mandatory padding is used
by such terminal capabilities as flash_screen (flash).
(Obsolete) Prior to internal changes developed in ncurses 5.9 (patches
20120825 through 20130126), the library used setbuf(3) to enable fully
buffered output when initializing the terminal. This was done, as in
SVr4 curses, to increase performance. For testing purposes, both of
ncurses and of certain applications, this feature was made optional.
Setting this variable disabled output buffering, leaving the output
stream in the original (usually line-buffered) mode.
Nowadays, ncurses performs its own buffering and does not require this
workaround; it does not modify the buffering of the standard output
stream. This approach makes signal handling, as for interrupts, more
robust. A drawback is that certain unconventional programs mixed
stdio(3) calls with ncurses calls and (usually) got the behavior they
expected. This is no longer the case; ncurses does not write to the
standard output file descriptor through a stdio-buffered stream.
As a special case, low-level API calls such as putp(3x) still use the
standard output stream. High-level curses calls such as printw(3x) do
not.
At initialization, ncurses inspects the TERM environment variable for
special cases where VT100 forms-drawing characters (and the
corresponding alternate character set terminfo capabilities) are known
to be unsupported by terminal types that otherwise claim VT100
compatibility. Specifically, when running in a UTF-8 locale, the Linux
virtual console device and the GNU screen(1) program ignore them. Set
this variable to a nonzero value to instruct ncurses that the
terminal's ACS support is broken; the library then outputs Unicode code
points that correspond to the forms-drawing characters. Set it to zero
(or a non-integer) to disable the special check for terminal type names
matching "linux" or "screen", directing ncurses to assume that the ACS
feature works if the terminal type description advertises it.
As an alternative to use of this variable, ncurses checks for an
extended terminfo numeric capability U8 that can be compiled using "tic
-x". Examples follow.
# 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 two-character name "U8" was chosen to permit its use via ncurses's
termcap interface.
At initialization, ncurses (in its debugging configuration) checks for
this variable's presence. If defined with an integral value, the
library calls curses_trace(3x) with that value as the argument.
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.
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.
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:
o 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.
o 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.
o 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.
o 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(1m):
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:
o the last terminal database to which ncurses wrote, if any, is
searched first
o the location specified by the TERMINFO environment variable
o $HOME/.terminfo
o locations listed in the TERMINFO_DIRS environment variable
o one or more locations whose names are configured and compiled
into the ncurses library, i.e.,
o /usr/share/terminfo (corresponding to the TERMINFO_DIRS
variable)
o /usr/share/terminfo (corresponding to the TERMINFO variable)
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.
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.
Many different ncurses configurations are possible, determined by the
options given to the configure script when building the library. Run
the script with the --help option to peruse them all. A few are of
particular significance to the application developer employing 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:
o Originally, the wide-character feature required the symbol
_XOPEN_SOURCE_EXTENDED but that was only valid for XPG4
(1996).
o Later, that was deemed conflicting with _XOPEN_SOURCE defined
to 500.
o 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.
o 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 header file installed for the wide-character library
is designed to be compatible with the non-wide library's header.
Only the size of the WINDOW structure differs; few applications
require more than pointers 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:
o curs_extend(3x) - miscellaneous curses extensions
o curs_inopts(3x) - curses input options
o curs_kernel(3x) - low-level curses routines
o curs_termattrs(3x) - curses environment query routines
o curs_termcap(3x) - curses emulation of termcap
o curs_terminfo(3x) - curses interface to terminfo database
o curs_util(3x) - 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.
/usr/share/tabset
tab stop initialization database
/usr/share/terminfo
compiled terminal capability database
X/Open Curses permits most functions it specifies to be made available
as macros as well. ncurses does so
o for functions that return values via their parameters,
o to support obsolete features,
o to reuse functions (for example, those that move the cursor before
another operation), and
o a few special cases.
If the standard output file descriptor of an ncurses program is
redirected to something that is not a terminal device, the library
writes screen updates to the standard error file descriptor. This was
an undocumented feature of SVr3.
See subsection "Header files" below regarding symbols exposed by
inclusion of curses.h.
ncurses enables an application to capture mouse events on certain
terminals, including xterm; see curs_mouse(3x).
ncurses provides a means of responding to window resizing events, as
when running in a GUI terminal emulator application such as xterm; see
resizeterm(3x) and wresize(3x).
ncurses allows an application to query the terminal for the presence of
a wide variety of special keys; see has_key(3x).
ncurses extends the fixed set of function key capabilities specified by
X/Open Curses by allowing the application programmer to define
additional key sequences at runtime; see define_key(3x),
key_defined(3x), and keyok(3x).
ncurses can exploit the capabilities of terminals implementing
ISO 6429/ECMA-48 SGR 39 and SGR 49 sequences, which allow an
application to reset the terminal to its original foreground and
background colors. From a user's perspective, the application is able
to draw colored text on a background whose color is set independently,
providing better control over color contrasts. See default_colors(3x).
An ncurses application can choose to hide the internal details of
WINDOW structures, instead using accessor functions such as
is_scrollok(3x).
ncurses enables an application to direct application output to a
printer attached to the terminal device; see curs_print(3x).
ncurses offers slk_attr(3x) as a counterpart of attr_get(3x) for soft-
label key lines, and extended_slk_color(3x) as a form of slk_color(3x)
that can gather color information from them when many colors are
supported.
Some extensions are only available if ncurses is compiled to support
them; section "ALTERNATE CONFIGURATIONS" describes how.
o Rudimentary support for multi-threaded applications may be
available; see curs_threads(3x).
o Functions that ease the management of multiple screens can be
exposed; see curs_sp_funcs(3x).
o To aid applications to debug their memory usage, ncurses optionally
offers functions to more aggressively free memory it dynamically
allocates itself; see curs_memleaks(3x).
o The library facilitates auditing and troubleshooting of its
behavior; see curs_trace(3x).
o The compiler option -DUSE_GETCAP causes the library to fall back to
reading /etc/termcap if the terminal setup code cannot find a term-
info 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 a cost in memory usage and
application launch latency.
PDCurses and NetBSD curses incorporate some ncurses extensions.
Individual man pages indicate where this is the case.
X/Open Curses defines two levels of conformance, "base" and "enhanced".
The latter includes several additional features, such as wide-character
and color support. ncurses intends base-level conformance with X/Open
Curses, and supports nearly all its enhanced features.
Differences between X/Open Curses and ncurses are documented in the
"PORTABILITY" sections of applicable man pages.
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.
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.
The header file curses.h itself 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:
o Starting with BSD curses, all implementations have included
<stdio.h>.
BSD curses included <curses.h> and <unctrl.h> from an internal
header file curses.ext ("ext" abbreviated "externs").
BSD curses used <stdio.h> internally (for printw and scanw), but
nothing in <curses.h> itself relied upon <stdio.h>.
o 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>.
o X/Open Curses is inconsistent with respect to SVr4 regarding
<unctrl.h>.
As noted in curs_util(3x), ncurses includes <unctrl.h> from
<curses.h> (like SVr4).
o 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.
o 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>.
o 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.
o 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.
Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey. Based on pcurses
by Pavel Curtis.
curs_variables(3x), terminfo(5), user_caps(5)
ncurses 6.4 2024-04-13 ncurses(3x)