ncurses 6.4 - patch 20240113

[ncurses.git] / man / ncurses.3x

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.\" Copyright 2018-2023,2024 Thomas E. Dickey                                *
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.\" $Id: ncurses.3x,v 1.197 2024/01/13 20:30:39 tom Exp $
.TH ncurses 3X 2024-01-13 "ncurses 6.4" "Library calls"
.ie \n(.g \{\
.ds `` \(lq
.ds '' \(rq
.\}
.el \{\
.ie t .ds `` ``
.el   .ds `` ""
.ie t .ds '' ''
.el   .ds '' ""
.\}
.
.de bP
.ie n  .IP \(bu 4
.el    .IP \(bu 2
..
.
.ds d @TERMINFO@
.SH NAME
\fB\%ncurses\fP \-
character-cell terminal interface with optimized output
.SH SYNOPSIS
.nf
\fB#include <curses.h>
.fi
.SH DESCRIPTION
The \fI\%ncurses\fP library routines give the user a
terminal-independent method of updating character screens with
reasonable optimization.
This implementation is \*(``new curses\*('' (\fI\%ncurses\fP) and
is the approved replacement for
4.4BSD classic curses, which has been discontinued.
This describes \fI\%ncurses\fP
version @NCURSES_MAJOR@.@NCURSES_MINOR@ (patch @NCURSES_PATCH@).
.PP
The \fI\%ncurses\fP library emulates the curses library of
System V Release 4 Unix (\*(``SVr4\*(''),
and XPG4 (X/Open Portability Guide) curses (also known as XSI curses).
XSI stands for X/Open System Interfaces Extension.
The \fI\%ncurses\fP library is freely redistributable in source form.
.PP
\fI\%ncurses\fP man pages employ several sections to clarify matters of
usage and interoperability with other \fIcurses\fP implementations.
.bP
\*(``NOTES\*('' describes matters and caveats of which any user of the
\fI\%ncurses\fP 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.
.bP
\*(``EXTENSIONS\*('' presents \fI\%ncurses\fP innovations beyond the
X/Open Curses standard and/or the SVr4 \fIcurses\fP implementation.
They are termed \fIextensions\fP to indicate that they cannot be
implemented solely by using the library API, but require access to the
library's internal state.
.bP
\*(``PORTABILITY\*('' discusses matters
(beyond the exercise of extensions)
that should be considered when writing to a \fIcurses\fP standard,
or to multiple implementations.
.bP
\*(``HISTORY\*('' examines points of detail in \fI\%ncurses\fP and other
\fIcurses\fP 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).
.PP
A program using these routines must be linked with the \fB\-lncurses\fP option,
or (if it has been generated) with the debugging library \fB\-lncurses_g\fP.
(Your system integrator may also have installed these libraries under
the names \fB\-lcurses\fP and \fB\-lcurses_g\fP.)
The ncurses_g library generates trace logs
(in a file called \*(``trace\*('' in the current directory)
that describe curses actions.
See section \*(``ALTERNATE CONFIGURATIONS\*('' below.
.PP
The \fI\%ncurses\fP package supports: overall screen, window and pad
manipulation; output to windows and pads; reading terminal input; control over
terminal and \fBcurses\fP input and output options; environment query
routines; color manipulation; use of soft label keys; terminfo capabilities;
and access to low-level terminal-manipulation routines.
.SS Initialization
The library uses the locale which the calling program has initialized.
That is normally done with \fBsetlocale\fP(3):
.PP
.RS 4
.EX
\fBsetlocale(LC_ALL, "");\fP
.EE
.RE
.PP
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.
.PP
The function \fBinitscr\fP or \fBnewterm\fP
must be called to initialize the library
before any of the other routines that deal with windows
and screens are used.
The routine \fBendwin\fP(3X) must be called before exiting.
.PP
To get character-at-a-time input without echoing (most
interactive, screen oriented programs want this), the following
sequence should be used:
.PP
.RS 4
.EX
\fBinitscr(); cbreak(); noecho();\fP
.EE
.RE
.PP
Most programs would additionally use the sequence:
.PP
.RS 4
.EX
\fBintrflush(stdscr, FALSE);\fP
\fBkeypad(stdscr, TRUE);\fP
.EE
.RE
.PP
Before a \fBcurses\fP 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 \fB@TPUT@ init\fP command
after the shell environment variable \fITERM\fP has been exported.
(The BSD-style \fB\%@TSET@\fP(1) utility also performs this function.)
See subsection \*(``Tabs and Initialization\*('' of \fBterminfo\fP(5).
.SS Overview
A
.I curses
library abstracts the terminal screen by representing all or part of it
as a
.I \%WINDOW
data structure.
A
.I window
is a rectangular grid of character cells,
addressed by row and column coordinates
.RI ( y ,
.IR x ),
with the upper left corner as (0, 0).
A window called \fB\%stdscr\fP,
the same size as the terminal screen,
is always available.
Create others with \fB\%newwin\fP(3X).
.PP
A
.I curses
library does not manage overlapping windows.
(See \fBpanel\fP(3X) if you desire this.)
You can either use \fB\%stdscr\fP to manage one screen-filling window,
or tile the screen into non-overlapping windows and not use
\fB\%stdscr\fP at all.
Mixing the two approaches will result in unpredictable,
and undesired,
effects.
.PP
Functions permit manipulation of a window and the
.I cursor
identifying the cell within it at which the next output operation will
occur.
Among those,
the most basic are \fBmove\fP(3X) and \fB\%addch\fP(3X):
these place the cursor and write a character to
.BR \%stdscr ,
respectively.
As a rule,
window-addressing functions feature names prefixed
(or infixed,
see below)
with \*(``w\*('';
these allow the user to specify a pointer to a
.I \%WINDOW.
Counterparts not thus prefixed
(or infixed)
affect \fB\%stdscr\fP.
Because moving the cursor prior to another operation is so common,
.I curses
generally also provides functions with a \*(``mv\*('' prefix as a
convenience.
Thus,
the library defines all of
\fB\%addch\fP,
\fB\%waddch\fP,
\fB\%mvaddch\fP,
and
\fB\%mvwaddch\fP.
When both prefixes are present,
the order of arguments is a
.I \%WINDOW
pointer first,
then a
.I y
and
.I x
coordinate pair.
.PP
Updating the terminal screen with every
.I curses
call can cause unpleasant flicker or inefficient use of the
communications channel to the device.
Therefore,
after using
.I curses
functions to accumulate a set of desired updates that make sense to
present together,
call \fB\%refresh\fP(3X) to tell the library to make the user's screen
look like \fBstdscr\fP.
.I \%ncurses
.\" X/Open Curses Issue 7 assumes some optimization will be done, but
.\" does not mandate it in any way.
.I 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
\fB\%terminfo\fP(3X) API,
a feature of every standard
.I curses
implementation.
.PP
Special windows called \fIpads\fP 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 \fB\%curs_pad\fP(3X).
.PP
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 \fB\%curs_attr\fP(3X).
.PP
.I curses
predefines constants for a small set of line-drawing and other graphics
corresponding to the DEC Alternate Character Set (ACS),
a feature of VT100 and other terminals.
See
\fB\%waddch\fP(3X) and
\fB\%wadd_wch\fP(3X).
.PP
.I 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
.I "escape sequence."
.I curses
translates these into unique
.I "key codes."
See \fB\%getch\fP(3X).
.SS "Effects of GUIs and Environment Variables"
The selection of an appropriate value of
.I TERM
in the process environment is essential to correct
.I curses
and
.I \%term\%info
library operation.
A well-configured system selects a correct
.I TERM
value automatically;
\fB\%tset\fP(1) may assist with troubleshooting exotic situations.
.PP
If the environment variables \fILINES\fP and \fI\%COLUMNS\fP are set,
or if the
.I curses
program is executing in a graphical windowing environment,
the information obtained thence overrides that obtained by
.IR \%term\%info .
An
.I \%ncurses
extension supports resizable terminals;
see \fB\%wresize\fP(3X).
.PP
If the environment variable \fI\%TERMINFO\fP is defined,
a
.I curses
program checks first for a terminal type description in the location it
identifies.
.I \%TERMINFO
is useful for developing experimental type descriptions or when write
permission to \fI\*d\fP is not available.
.PP
See section \*(``ENVIRONMENT\*('' below.
.SS "Naming Conventions"
Many
.I curses
functions have two or more versions.
Those prefixed with \*(``w\*('' require a window argument.
Four functions prefixed with \*(``p\*('' require a pad argument.
Those without a prefix generally operate on \fB\%stdscr\fP.
.PP
In function synopses,
.I \%ncurses
man pages apply the following names to parameters.
.PP
.TS
center;
Li L.
bf      \fIbool\fP (\fBTRUE\fP or \fBFALSE\fP)
win     pointer to \fIWINDOW\fP
pad     pointer to \fIWINDOW\fP that is a pad
.TE
.SS "Wide and Non-wide Character Configurations"
This manual page describes functions that appear in any configuration
of the library.
There are two common configurations;
see section \*(``ALTERNATE CONFIGURATIONS\*('' below.
.TP 10 \" "ncursesw" + 2n
.I \%ncurses
is the library in its \*(``non-wide\*('' configuration,
handling only eight-bit characters.
It stores a character combined with attributes in a
.I \%chtype
datum,
which is often an alias of
.I int.
.IP
Attributes alone
(with no corresponding character)
can be stored in variables of
.I \%chtype
or
.I \%attr_t
type.
In either case,
they are represented as an integral bit mask.
.IP
Each cell of a
.I \%WINDOW
is stored as a
.I \%chtype.
.TP 10
.I \%ncursesw
is the library in its \*(``wide\*('' configuration,
which handles character encodings requiring a larger data type than
.I \%char
(a byte-sized type)
can represent.
It adds about one third more calls using additional data types that
can store such
.I multibyte
characters.
.RS 10 \" same as foregoing tag width
.TP 9 \" "cchar_t" + 2n
.I \%cchar_t
corresponds to the non-wide configuration's
.I \%chtype.
It always a structure type,
because it stores more data than fits into an integral type.
A character code may not be representable as a
.I \%char,
and moreover more than one character may occupy a cell
(as with accent marks and other diacritics).
Each character is of type
.I \%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
.I \%chtype.
.PP
Each cell of a
.I \%WINDOW
is stored as a
.I \%cchar_t.
.PP
The \fB\%setcchar\fP(3X) and \fB\%getcchar\fP(3X)
functions store and retrieve the data from a
.I \%cchar_t
structure.
The wide library API of
.I \%ncurses
depends on two data types standardized by ISO C95.
.TP 9
.I \%wchar_t
stores a wide character.
Like
.I \%chtype,
it may be an alias of
.I int.
Depending on the character encoding,
a wide character may be
.I spacing,
meaning that it occupies a character cell by itself and typically
accompanies cursor advancement,
or
.I 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.
.TP 9
.I \%wint_t
can store a
.I \%wchar_t
or the constant
.BR \%WEOF ,
analogously to the
.IR int -sized
character manipulation functions of ISO C and its constant
.BR \%EOF .
.RE
.IP
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,
\fB\%waddch\fP becomes \fB\%wadd_wch\fP.
.IP
This convention is inapplicable to some non-wide function names,
so other transformations are used for the wide configuration:
in the window background management functions,
\*(``bkgd\*('' becomes \*(``bkgrnd\*('';
the window border-drawing and -clearing functions are suffixed with
\*(``_set\*(''.
.\"
.SS "Function Name Index"
The following table lists the
.I curses
functions provided in the non-wide and wide APIs and the corresponding
man pages that describe them.
Those flagged with \*(``*\*(''
are
.IR \%ncurses -specific,
neither described by X/Open Curses nor present in SVr4.
.PP
.TS
center tab(/);
l l .
\f(BIcurses\fP Function Name/Man Page
_
COLOR_PAIR/\fBcurs_color\fP(3X)
PAIR_NUMBER/\fBcurs_color\fP(3X)
add_wch/\fBcurs_add_wch\fP(3X)
add_wchnstr/\fBcurs_add_wchstr\fP(3X)
add_wchstr/\fBcurs_add_wchstr\fP(3X)
addch/\fBcurs_addch\fP(3X)
addchnstr/\fBcurs_addchstr\fP(3X)
addchstr/\fBcurs_addchstr\fP(3X)
addnstr/\fBcurs_addstr\fP(3X)
addnwstr/\fBcurs_addwstr\fP(3X)
addstr/\fBcurs_addstr\fP(3X)
addwstr/\fBcurs_addwstr\fP(3X)
alloc_pair/\fBnew_pair\fP(3X)*
assume_default_colors/\fBdefault_colors\fP(3X)*
attr_get/\fBcurs_attr\fP(3X)
attr_off/\fBcurs_attr\fP(3X)
attr_on/\fBcurs_attr\fP(3X)
attr_set/\fBcurs_attr\fP(3X)
attroff/\fBcurs_attr\fP(3X)
attron/\fBcurs_attr\fP(3X)
attrset/\fBcurs_attr\fP(3X)
baudrate/\fBcurs_termattrs\fP(3X)
beep/\fBcurs_beep\fP(3X)
bkgd/\fBcurs_bkgd\fP(3X)
bkgdset/\fBcurs_bkgd\fP(3X)
bkgrnd/\fBcurs_bkgrnd\fP(3X)
bkgrndset/\fBcurs_bkgrnd\fP(3X)
border/\fBcurs_border\fP(3X)
border_set/\fBcurs_border_set\fP(3X)
box/\fBcurs_border\fP(3X)
box_set/\fBcurs_border_set\fP(3X)
can_change_color/\fBcurs_color\fP(3X)
cbreak/\fBcurs_inopts\fP(3X)
chgat/\fBcurs_attr\fP(3X)
clear/\fBcurs_clear\fP(3X)
clearok/\fBcurs_outopts\fP(3X)
clrtobot/\fBcurs_clear\fP(3X)
clrtoeol/\fBcurs_clear\fP(3X)
color_content/\fBcurs_color\fP(3X)
color_set/\fBcurs_attr\fP(3X)
copywin/\fBcurs_overlay\fP(3X)
curs_set/\fBcurs_kernel\fP(3X)
curses_trace/\fBcurs_trace\fP(3X)*
curses_version/\fBcurs_extend\fP(3X)*
def_prog_mode/\fBcurs_kernel\fP(3X)
def_shell_mode/\fBcurs_kernel\fP(3X)
define_key/\fBdefine_key\fP(3X)*
del_curterm/\fBcurs_terminfo\fP(3X)
delay_output/\fBcurs_util\fP(3X)
delch/\fBcurs_delch\fP(3X)
deleteln/\fBcurs_deleteln\fP(3X)
delscreen/\fBcurs_initscr\fP(3X)
delwin/\fBcurs_window\fP(3X)
derwin/\fBcurs_window\fP(3X)
doupdate/\fBcurs_refresh\fP(3X)
dupwin/\fBcurs_window\fP(3X)
echo/\fBcurs_inopts\fP(3X)
echo_wchar/\fBcurs_add_wch\fP(3X)
echochar/\fBcurs_addch\fP(3X)
endwin/\fBcurs_initscr\fP(3X)
erase/\fBcurs_clear\fP(3X)
erasechar/\fBcurs_termattrs\fP(3X)
erasewchar/\fBcurs_termattrs\fP(3X)
exit_curses/\fBcurs_memleaks\fP(3X)*
exit_terminfo/\fBcurs_memleaks\fP(3X)*
extended_color_content/\fBcurs_color\fP(3X)*
extended_pair_content/\fBcurs_color\fP(3X)*
extended_slk_color/\fBcurs_slk\fP(3X)*
filter/\fBcurs_util\fP(3X)
find_pair/\fBnew_pair\fP(3X)*
flash/\fBcurs_beep\fP(3X)
flushinp/\fBcurs_util\fP(3X)
free_pair/\fBnew_pair\fP(3X)*
get_wch/\fBcurs_get_wch\fP(3X)
get_wstr/\fBcurs_get_wstr\fP(3X)
getattrs/\fBcurs_attr\fP(3X)
getbegx/\fBcurs_legacy\fP(3X)*
getbegy/\fBcurs_legacy\fP(3X)*
getbegyx/\fBcurs_getyx\fP(3X)
getbkgd/\fBcurs_bkgd\fP(3X)
getbkgrnd/\fBcurs_bkgrnd\fP(3X)
getcchar/\fBcurs_getcchar\fP(3X)
getch/\fBcurs_getch\fP(3X)
getcurx/\fBcurs_legacy\fP(3X)*
getcury/\fBcurs_legacy\fP(3X)*
getmaxx/\fBcurs_legacy\fP(3X)*
getmaxy/\fBcurs_legacy\fP(3X)*
getmaxyx/\fBcurs_getyx\fP(3X)
getmouse/\fBcurs_mouse\fP(3X)*
getn_wstr/\fBcurs_get_wstr\fP(3X)
getnstr/\fBcurs_getstr\fP(3X)
getparx/\fBcurs_legacy\fP(3X)*
getpary/\fBcurs_legacy\fP(3X)*
getparyx/\fBcurs_getyx\fP(3X)
getstr/\fBcurs_getstr\fP(3X)
getsyx/\fBcurs_kernel\fP(3X)
getwin/\fBcurs_util\fP(3X)
getyx/\fBcurs_getyx\fP(3X)
halfdelay/\fBcurs_inopts\fP(3X)
has_colors/\fBcurs_color\fP(3X)
has_ic/\fBcurs_termattrs\fP(3X)
has_il/\fBcurs_termattrs\fP(3X)
has_key/\fBcurs_getch\fP(3X)*
has_mouse/\fBcurs_mouse\fP(3X)*
hline/\fBcurs_border\fP(3X)
hline_set/\fBcurs_border_set\fP(3X)
idcok/\fBcurs_outopts\fP(3X)
idlok/\fBcurs_outopts\fP(3X)
immedok/\fBcurs_outopts\fP(3X)
in_wch/\fBcurs_in_wch\fP(3X)
in_wchnstr/\fBcurs_in_wchstr\fP(3X)
in_wchstr/\fBcurs_in_wchstr\fP(3X)
inch/\fBcurs_inch\fP(3X)
inchnstr/\fBcurs_inchstr\fP(3X)
inchstr/\fBcurs_inchstr\fP(3X)
init_color/\fBcurs_color\fP(3X)
init_extended_color/\fBcurs_color\fP(3X)*
init_extended_pair/\fBcurs_color\fP(3X)*
init_pair/\fBcurs_color\fP(3X)
initscr/\fBcurs_initscr\fP(3X)
innstr/\fBcurs_instr\fP(3X)
innwstr/\fBcurs_inwstr\fP(3X)
ins_nwstr/\fBcurs_ins_wstr\fP(3X)
ins_wch/\fBcurs_ins_wch\fP(3X)
ins_wstr/\fBcurs_ins_wstr\fP(3X)
insch/\fBcurs_insch\fP(3X)
insdelln/\fBcurs_deleteln\fP(3X)
insertln/\fBcurs_deleteln\fP(3X)
insnstr/\fBcurs_insstr\fP(3X)
insstr/\fBcurs_insstr\fP(3X)
instr/\fBcurs_instr\fP(3X)
intrflush/\fBcurs_inopts\fP(3X)
inwstr/\fBcurs_inwstr\fP(3X)
is_cbreak/\fBcurs_inopts\fP(3X)*
is_cleared/\fBcurs_opaque\fP(3X)*
is_echo/\fBcurs_inopts\fP(3X)*
is_idcok/\fBcurs_opaque\fP(3X)*
is_idlok/\fBcurs_opaque\fP(3X)*
is_immedok/\fBcurs_opaque\fP(3X)*
is_keypad/\fBcurs_opaque\fP(3X)*
is_leaveok/\fBcurs_opaque\fP(3X)*
is_linetouched/\fBcurs_touch\fP(3X)
is_nl/\fBcurs_inopts\fP(3X)*
is_nodelay/\fBcurs_opaque\fP(3X)*
is_notimeout/\fBcurs_opaque\fP(3X)*
is_pad/\fBcurs_opaque\fP(3X)*
is_raw/\fBcurs_inopts\fP(3X)*
is_scrollok/\fBcurs_opaque\fP(3X)*
is_subwin/\fBcurs_opaque\fP(3X)*
is_syncok/\fBcurs_opaque\fP(3X)*
is_term_resized/\fBresizeterm\fP(3X)*
is_wintouched/\fBcurs_touch\fP(3X)
isendwin/\fBcurs_initscr\fP(3X)
key_defined/\fBkey_defined\fP(3X)*
key_name/\fBcurs_util\fP(3X)
keybound/\fBkeybound\fP(3X)*
keyname/\fBcurs_util\fP(3X)
keyok/\fBkeyok\fP(3X)*
keypad/\fBcurs_inopts\fP(3X)
killchar/\fBcurs_termattrs\fP(3X)
killwchar/\fBcurs_termattrs\fP(3X)
leaveok/\fBcurs_outopts\fP(3X)
longname/\fBcurs_termattrs\fP(3X)
mcprint/\fBcurs_print\fP(3X)*
meta/\fBcurs_inopts\fP(3X)
mouse_trafo/\fBcurs_mouse\fP(3X)*
mouseinterval/\fBcurs_mouse\fP(3X)*
mousemask/\fBcurs_mouse\fP(3X)*
move/\fBcurs_move\fP(3X)
mvadd_wch/\fBcurs_add_wch\fP(3X)
mvadd_wchnstr/\fBcurs_add_wchstr\fP(3X)
mvadd_wchstr/\fBcurs_add_wchstr\fP(3X)
mvaddch/\fBcurs_addch\fP(3X)
mvaddchnstr/\fBcurs_addchstr\fP(3X)
mvaddchstr/\fBcurs_addchstr\fP(3X)
mvaddnstr/\fBcurs_addstr\fP(3X)
mvaddnwstr/\fBcurs_addwstr\fP(3X)
mvaddstr/\fBcurs_addstr\fP(3X)
mvaddwstr/\fBcurs_addwstr\fP(3X)
mvchgat/\fBcurs_attr\fP(3X)
mvcur/\fBcurs_terminfo\fP(3X)
mvdelch/\fBcurs_delch\fP(3X)
mvderwin/\fBcurs_window\fP(3X)
mvget_wch/\fBcurs_get_wch\fP(3X)
mvget_wstr/\fBcurs_get_wstr\fP(3X)
mvgetch/\fBcurs_getch\fP(3X)
mvgetn_wstr/\fBcurs_get_wstr\fP(3X)
mvgetnstr/\fBcurs_getstr\fP(3X)
mvgetstr/\fBcurs_getstr\fP(3X)
mvhline/\fBcurs_border\fP(3X)
mvhline_set/\fBcurs_border_set\fP(3X)
mvin_wch/\fBcurs_in_wch\fP(3X)
mvin_wchnstr/\fBcurs_in_wchstr\fP(3X)
mvin_wchstr/\fBcurs_in_wchstr\fP(3X)
mvinch/\fBcurs_inch\fP(3X)
mvinchnstr/\fBcurs_inchstr\fP(3X)
mvinchstr/\fBcurs_inchstr\fP(3X)
mvinnstr/\fBcurs_instr\fP(3X)
mvinnwstr/\fBcurs_inwstr\fP(3X)
mvins_nwstr/\fBcurs_ins_wstr\fP(3X)
mvins_wch/\fBcurs_ins_wch\fP(3X)
mvins_wstr/\fBcurs_ins_wstr\fP(3X)
mvinsch/\fBcurs_insch\fP(3X)
mvinsnstr/\fBcurs_insstr\fP(3X)
mvinsstr/\fBcurs_insstr\fP(3X)
mvinstr/\fBcurs_instr\fP(3X)
mvinwstr/\fBcurs_inwstr\fP(3X)
mvprintw/\fBcurs_printw\fP(3X)
mvscanw/\fBcurs_scanw\fP(3X)
mvvline/\fBcurs_border\fP(3X)
mvvline_set/\fBcurs_border_set\fP(3X)
mvwadd_wch/\fBcurs_add_wch\fP(3X)
mvwadd_wchnstr/\fBcurs_add_wchstr\fP(3X)
mvwadd_wchstr/\fBcurs_add_wchstr\fP(3X)
mvwaddch/\fBcurs_addch\fP(3X)
mvwaddchnstr/\fBcurs_addchstr\fP(3X)
mvwaddchstr/\fBcurs_addchstr\fP(3X)
mvwaddnstr/\fBcurs_addstr\fP(3X)
mvwaddnwstr/\fBcurs_addwstr\fP(3X)
mvwaddstr/\fBcurs_addstr\fP(3X)
mvwaddwstr/\fBcurs_addwstr\fP(3X)
mvwchgat/\fBcurs_attr\fP(3X)
mvwdelch/\fBcurs_delch\fP(3X)
mvwget_wch/\fBcurs_get_wch\fP(3X)
mvwget_wstr/\fBcurs_get_wstr\fP(3X)
mvwgetch/\fBcurs_getch\fP(3X)
mvwgetn_wstr/\fBcurs_get_wstr\fP(3X)
mvwgetnstr/\fBcurs_getstr\fP(3X)
mvwgetstr/\fBcurs_getstr\fP(3X)
mvwhline/\fBcurs_border\fP(3X)
mvwhline_set/\fBcurs_border_set\fP(3X)
mvwin/\fBcurs_window\fP(3X)
mvwin_wch/\fBcurs_in_wch\fP(3X)
mvwin_wchnstr/\fBcurs_in_wchstr\fP(3X)
mvwin_wchstr/\fBcurs_in_wchstr\fP(3X)
mvwinch/\fBcurs_inch\fP(3X)
mvwinchnstr/\fBcurs_inchstr\fP(3X)
mvwinchstr/\fBcurs_inchstr\fP(3X)
mvwinnstr/\fBcurs_instr\fP(3X)
mvwinnwstr/\fBcurs_inwstr\fP(3X)
mvwins_nwstr/\fBcurs_ins_wstr\fP(3X)
mvwins_wch/\fBcurs_ins_wch\fP(3X)
mvwins_wstr/\fBcurs_ins_wstr\fP(3X)
mvwinsch/\fBcurs_insch\fP(3X)
mvwinsnstr/\fBcurs_insstr\fP(3X)
mvwinsstr/\fBcurs_insstr\fP(3X)
mvwinstr/\fBcurs_instr\fP(3X)
mvwinwstr/\fBcurs_inwstr\fP(3X)
mvwprintw/\fBcurs_printw\fP(3X)
mvwscanw/\fBcurs_scanw\fP(3X)
mvwvline/\fBcurs_border\fP(3X)
mvwvline_set/\fBcurs_border_set\fP(3X)
napms/\fBcurs_kernel\fP(3X)
newpad/\fBcurs_pad\fP(3X)
newterm/\fBcurs_initscr\fP(3X)
newwin/\fBcurs_window\fP(3X)
nl/\fBcurs_inopts\fP(3X)
nocbreak/\fBcurs_inopts\fP(3X)
nodelay/\fBcurs_inopts\fP(3X)
noecho/\fBcurs_inopts\fP(3X)
nofilter/\fBcurs_util\fP(3X)*
nonl/\fBcurs_inopts\fP(3X)
noqiflush/\fBcurs_inopts\fP(3X)
noraw/\fBcurs_inopts\fP(3X)
notimeout/\fBcurs_inopts\fP(3X)
overlay/\fBcurs_overlay\fP(3X)
overwrite/\fBcurs_overlay\fP(3X)
pair_content/\fBcurs_color\fP(3X)
pecho_wchar/\fBcurs_pad\fP(3X)
pechochar/\fBcurs_pad\fP(3X)
pnoutrefresh/\fBcurs_pad\fP(3X)
prefresh/\fBcurs_pad\fP(3X)
printw/\fBcurs_printw\fP(3X)
putp/\fBcurs_terminfo\fP(3X)
putwin/\fBcurs_util\fP(3X)
qiflush/\fBcurs_inopts\fP(3X)
raw/\fBcurs_inopts\fP(3X)
redrawwin/\fBcurs_refresh\fP(3X)
refresh/\fBcurs_refresh\fP(3X)
reset_color_pairs/\fBcurs_color\fP(3X)*
reset_prog_mode/\fBcurs_kernel\fP(3X)
reset_shell_mode/\fBcurs_kernel\fP(3X)
resetty/\fBcurs_kernel\fP(3X)
resize_term/\fBresizeterm\fP(3X)*
resizeterm/\fBresizeterm\fP(3X)*
restartterm/\fBcurs_terminfo\fP(3X)
ripoffline/\fBcurs_kernel\fP(3X)
savetty/\fBcurs_kernel\fP(3X)
scanw/\fBcurs_scanw\fP(3X)
scr_dump/\fBcurs_scr_dump\fP(3X)
scr_init/\fBcurs_scr_dump\fP(3X)
scr_restore/\fBcurs_scr_dump\fP(3X)
scr_set/\fBcurs_scr_dump\fP(3X)
scrl/\fBcurs_scroll\fP(3X)
scroll/\fBcurs_scroll\fP(3X)
scrollok/\fBcurs_outopts\fP(3X)
set_curterm/\fBcurs_terminfo\fP(3X)
set_term/\fBcurs_initscr\fP(3X)
setcchar/\fBcurs_getcchar\fP(3X)
setscrreg/\fBcurs_outopts\fP(3X)
setsyx/\fBcurs_kernel\fP(3X)
setupterm/\fBcurs_terminfo\fP(3X)
slk_attr/\fBcurs_slk\fP(3X)*
slk_attr_off/\fBcurs_slk\fP(3X)
slk_attr_on/\fBcurs_slk\fP(3X)
slk_attr_set/\fBcurs_slk\fP(3X)
slk_attroff/\fBcurs_slk\fP(3X)
slk_attron/\fBcurs_slk\fP(3X)
slk_attrset/\fBcurs_slk\fP(3X)
slk_clear/\fBcurs_slk\fP(3X)
slk_color/\fBcurs_slk\fP(3X)
slk_init/\fBcurs_slk\fP(3X)
slk_label/\fBcurs_slk\fP(3X)
slk_noutrefresh/\fBcurs_slk\fP(3X)
slk_refresh/\fBcurs_slk\fP(3X)
slk_restore/\fBcurs_slk\fP(3X)
slk_set/\fBcurs_slk\fP(3X)
slk_touch/\fBcurs_slk\fP(3X)
slk_wset/\fBcurs_slk\fP(3X)
standend/\fBcurs_attr\fP(3X)
standout/\fBcurs_attr\fP(3X)
start_color/\fBcurs_color\fP(3X)
subpad/\fBcurs_pad\fP(3X)
subwin/\fBcurs_window\fP(3X)
syncok/\fBcurs_window\fP(3X)
term_attrs/\fBcurs_termattrs\fP(3X)
termattrs/\fBcurs_termattrs\fP(3X)
termname/\fBcurs_termattrs\fP(3X)
tgetent/\fBcurs_termcap\fP(3X)
tgetflag/\fBcurs_termcap\fP(3X)
tgetnum/\fBcurs_termcap\fP(3X)
tgetstr/\fBcurs_termcap\fP(3X)
tgoto/\fBcurs_termcap\fP(3X)
tigetflag/\fBcurs_terminfo\fP(3X)
tigetnum/\fBcurs_terminfo\fP(3X)
tigetstr/\fBcurs_terminfo\fP(3X)
timeout/\fBcurs_inopts\fP(3X)
tiparm/\fBcurs_terminfo\fP(3X)
tiparm_s/\fBcurs_terminfo\fP(3X)*
tiscan_s/\fBcurs_terminfo\fP(3X)*
touchline/\fBcurs_touch\fP(3X)
touchwin/\fBcurs_touch\fP(3X)
tparm/\fBcurs_terminfo\fP(3X)
tputs/\fBcurs_termcap\fP(3X)
tputs/\fBcurs_terminfo\fP(3X)
trace/\fBcurs_trace\fP(3X)*
typeahead/\fBcurs_inopts\fP(3X)
unctrl/\fBcurs_util\fP(3X)
unget_wch/\fBcurs_get_wch\fP(3X)
ungetch/\fBcurs_getch\fP(3X)
ungetmouse/\fBcurs_mouse\fP(3X)*
untouchwin/\fBcurs_touch\fP(3X)
use_default_colors/\fBdefault_colors\fP(3X)*
use_env/\fBcurs_util\fP(3X)
use_extended_names/\fBcurs_extend\fP(3X)*
use_legacy_coding/\fBlegacy_coding\fP(3X)*
use_tioctl/\fBcurs_util\fP(3X)*
vid_attr/\fBcurs_terminfo\fP(3X)
vid_puts/\fBcurs_terminfo\fP(3X)
vidattr/\fBcurs_terminfo\fP(3X)
vidputs/\fBcurs_terminfo\fP(3X)
vline/\fBcurs_border\fP(3X)
vline_set/\fBcurs_border_set\fP(3X)
vw_printw/\fBcurs_printw\fP(3X)
vw_scanw/\fBcurs_scanw\fP(3X)
vwprintw/\fBcurs_printw\fP(3X)
vwscanw/\fBcurs_scanw\fP(3X)
wadd_wch/\fBcurs_add_wch\fP(3X)
wadd_wchnstr/\fBcurs_add_wchstr\fP(3X)
wadd_wchstr/\fBcurs_add_wchstr\fP(3X)
waddch/\fBcurs_addch\fP(3X)
waddchnstr/\fBcurs_addchstr\fP(3X)
waddchstr/\fBcurs_addchstr\fP(3X)
waddnstr/\fBcurs_addstr\fP(3X)
waddnwstr/\fBcurs_addwstr\fP(3X)
waddstr/\fBcurs_addstr\fP(3X)
waddwstr/\fBcurs_addwstr\fP(3X)
wattr_get/\fBcurs_attr\fP(3X)
wattr_off/\fBcurs_attr\fP(3X)
wattr_on/\fBcurs_attr\fP(3X)
wattr_set/\fBcurs_attr\fP(3X)
wattroff/\fBcurs_attr\fP(3X)
wattron/\fBcurs_attr\fP(3X)
wattrset/\fBcurs_attr\fP(3X)
wbkgd/\fBcurs_bkgd\fP(3X)
wbkgdset/\fBcurs_bkgd\fP(3X)
wbkgrnd/\fBcurs_bkgrnd\fP(3X)
wbkgrndset/\fBcurs_bkgrnd\fP(3X)
wborder/\fBcurs_border\fP(3X)
wborder_set/\fBcurs_border_set\fP(3X)
wchgat/\fBcurs_attr\fP(3X)
wclear/\fBcurs_clear\fP(3X)
wclrtobot/\fBcurs_clear\fP(3X)
wclrtoeol/\fBcurs_clear\fP(3X)
wcolor_set/\fBcurs_attr\fP(3X)
wcursyncup/\fBcurs_window\fP(3X)
wdelch/\fBcurs_delch\fP(3X)
wdeleteln/\fBcurs_deleteln\fP(3X)
wecho_wchar/\fBcurs_add_wch\fP(3X)
wechochar/\fBcurs_addch\fP(3X)
wenclose/\fBcurs_mouse\fP(3X)*
werase/\fBcurs_clear\fP(3X)
wget_wch/\fBcurs_get_wch\fP(3X)
wget_wstr/\fBcurs_get_wstr\fP(3X)
wgetbkgrnd/\fBcurs_bkgrnd\fP(3X)
wgetch/\fBcurs_getch\fP(3X)
wgetdelay/\fBcurs_opaque\fP(3X)*
wgetn_wstr/\fBcurs_get_wstr\fP(3X)
wgetnstr/\fBcurs_getstr\fP(3X)
wgetparent/\fBcurs_opaque\fP(3X)*
wgetscrreg/\fBcurs_opaque\fP(3X)*
wgetstr/\fBcurs_getstr\fP(3X)
whline/\fBcurs_border\fP(3X)
whline_set/\fBcurs_border_set\fP(3X)
win_wch/\fBcurs_in_wch\fP(3X)
win_wchnstr/\fBcurs_in_wchstr\fP(3X)
win_wchstr/\fBcurs_in_wchstr\fP(3X)
winch/\fBcurs_inch\fP(3X)
winchnstr/\fBcurs_inchstr\fP(3X)
winchstr/\fBcurs_inchstr\fP(3X)
winnstr/\fBcurs_instr\fP(3X)
winnwstr/\fBcurs_inwstr\fP(3X)
wins_nwstr/\fBcurs_ins_wstr\fP(3X)
wins_wch/\fBcurs_ins_wch\fP(3X)
wins_wstr/\fBcurs_ins_wstr\fP(3X)
winsch/\fBcurs_insch\fP(3X)
winsdelln/\fBcurs_deleteln\fP(3X)
winsertln/\fBcurs_deleteln\fP(3X)
winsnstr/\fBcurs_insstr\fP(3X)
winsstr/\fBcurs_insstr\fP(3X)
winstr/\fBcurs_instr\fP(3X)
winwstr/\fBcurs_inwstr\fP(3X)
wmouse_trafo/\fBcurs_mouse\fP(3X)*
wmove/\fBcurs_move\fP(3X)
wnoutrefresh/\fBcurs_refresh\fP(3X)
wprintw/\fBcurs_printw\fP(3X)
wredrawln/\fBcurs_refresh\fP(3X)
wrefresh/\fBcurs_refresh\fP(3X)
wresize/\fBwresize\fP(3X)*
wscanw/\fBcurs_scanw\fP(3X)
wscrl/\fBcurs_scroll\fP(3X)
wsetscrreg/\fBcurs_outopts\fP(3X)
wstandend/\fBcurs_attr\fP(3X)
wstandout/\fBcurs_attr\fP(3X)
wsyncdown/\fBcurs_window\fP(3X)
wsyncup/\fBcurs_window\fP(3X)
wtimeout/\fBcurs_inopts\fP(3X)
wtouchln/\fBcurs_touch\fP(3X)
wunctrl/\fBcurs_util\fP(3X)
wvline/\fBcurs_border\fP(3X)
wvline_set/\fBcurs_border_set\fP(3X)
.TE
.PP
Depending on the configuration,
additional sets of functions may be available:
.RS 3
.TP 5
\fBcurs_memleaks\fP(3X) - curses memory-leak checking
.TP 5
\fBcurs_sp_funcs\fP(3X) - curses screen-pointer extension
.TP 5
\fBcurs_threads\fP(3X) - curses thread support
.TP 5
\fBcurs_trace\fP(3X) - curses debugging routines
.RE
.SH RETURN VALUE
Unless otherwise noted,
functions that return an integer return \fBOK\fP on success and
\fBERR\fP on failure.
Functions that return pointers return \fBNULL\fP on failure.
Typically,
.I \%ncurses
treats a null pointer passed as a function parameter as a failure.
.PP
Functions with a \*(``mv\*('' prefix first perform cursor movement using
\fB\%wmove\fP and fail if the position is outside the window,
or
(for \*(``mvw\*('' functions)
if the
.I \%WINDOW
pointer is null.
.SH ENVIRONMENT
The following environment symbols are useful for customizing the
runtime behavior of the \fI\%ncurses\fP library.
The most important ones have been already discussed in detail.
.SS "\fICC\fP (command character)"
When set,
change the
.B \%command_character
.RB ( \%cmdch )
capability value of loaded
.I \%term\%info
entries to the value of this variable.
Very few
.I \%term\%info
entries provide this feature.
.PP
Because this name is also used in development environments to represent
the C compiler's name,
\fI\%ncurses\fP ignores it if it does not happen to be a single
character.
.SS "\fIBAUDRATE\fP"
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, \fI\%ncurses\fP uses 9600.
This allows testers to construct repeatable test-cases
that take into account costs that depend on baudrate.
.SS "\fICOLUMNS\fP"
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 \fI\%COLUMNS\fP value nor the terminal's screen size is available,
\fI\%ncurses\fP uses the size which may be specified in the terminfo
database
(i.e., the \fBcols\fP capability).
.PP
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 \fI\%COLUMNS\fP and/or \fILINES\fP overrides the library's use
of the screen size obtained from the operating system.
.PP
Either \fI\%COLUMNS\fP or \fILINES\fP 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, \fBlines\fP and \fBcols\fP should not be specified in
a terminal description for terminals which are run as emulations.
.PP
Use the \fBuse_env\fP function to disable all use of external environment
(but not including system calls) to determine the screen size.
Use the \fBuse_tioctl\fP function to update \fI\%COLUMNS\fP or
\fILINES\fP to match the screen size obtained from system calls or the
terminal database.
.SS "\fIESCDELAY\fP"
Specifies the total time,
in milliseconds,
for which \fI\%ncurses\fP 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.
.PP
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.
.PP
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.
.PP
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 \fB\%ESCDELAY\fP
in either form,
but setting the environment variable rather than the global variable
does not create problems when compiling an application.
.SS "\fIHOME\fP"
Tells \fI\%ncurses\fP where your home directory is.
That is where it may read and write auxiliary terminal descriptions:
.PP
.RS 4
.EX
$HOME/.termcap
$HOME/.terminfo
.EE
.RE
.SS "\fILINES\fP"
Like \fI\%COLUMNS\fP, specify the height of the screen in characters.
See \fI\%COLUMNS\fP for a detailed description.
.SS "\fIMOUSE_BUTTONS_123\fP"
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:
.PP
.RS 4
.EX
1 = left
2 = right
3 = middle.
.EE
.RE
.PP
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, \fI\%ncurses\fP uses 132.
.SS "\fINCURSES_ASSUMED_COLORS\fP"
Override the compiled-in assumption that the
terminal's default colors are white-on-black
(see \fBdefault_colors\fP(3X)).
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 \fI\%ncurses\fP 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 \fBmax_colors\fP value is allowed.
.SS "\fINCURSES_CONSOLE2\fP"
This applies only to the MinGW port of \fI\%ncurses\fP.
.PP
The \fBConsole2\fP program's handling of the Microsoft Console API call
\fBCreateConsoleScreenBuffer\fP 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 \fBNCGDB\fP has the same effect.
.SS "\fINCURSES_GPM_TERMS\fP"
This applies only to \fI\%ncurses\fP configured to use the GPM
interface.
.PP
If present,
the environment variable is a list of one or more terminal names
against which the \fITERM\fP environment variable is matched.
Setting it to an empty value disables the GPM interface;
using the built-in support for xterm, etc.
.PP
If the environment variable is absent,
\fI\%ncurses\fP will attempt to open GPM if \fITERM\fP contains
\*(``linux\*(''.
.SS "\fINCURSES_NO_HARD_TABS\fP"
\fI\%ncurses\fP may use tabs as part of cursor movement optimization.
In some cases,
your terminal driver may not handle these properly.
Set this environment variable to any value to disable the feature.
You can also adjust your \fBstty\fP(1) settings to avoid the problem.
.SS "\fINCURSES_NO_MAGIC_COOKIE\fP"
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 to any value.
.SS "\fINCURSES_NO_PADDING\fP"
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.
.PP
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.
.PP
Set the \fI\%NCURSES_NO_PADDING\fP environment variable
to disable all but mandatory padding.
Mandatory padding is used as a part of special control
sequences such as \fBflash\fP.
.SS "\fINCURSES_NO_SETBUF\fP"
This setting is obsolete.
Before changes
.RS 3
.bP
started with 5.9 patch 20120825
and
.bP
continued
though 5.9 patch 20130126
.RE
.PP
\fI\%ncurses\fP enabled buffered output during terminal initialization.
This was done (as in SVr4 curses) for performance reasons.
For testing purposes, both of \fI\%ncurses\fP and certain applications,
this feature was made optional.
Setting the \fI\%NCURSES_NO_SETBUF\fP variable
disabled output buffering, leaving the output in the original (usually
line buffered) mode.
.PP
In the current implementation,
\fI\%ncurses\fP performs its own buffering and does not require this
workaround.
It does not modify the buffering of the standard output.
.PP
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 \fI\%stdio\fP(3) calls with \fI\%ncurses\fP calls and (usually)
work.
This is no longer possible since \fI\%ncurses\fP 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 \fBputp\fP still use the
standard output.
But high-level curses calls do not.
.SS "\fINCURSES_NO_UTF8_ACS\fP"
During initialization, the \fI\%ncurses\fP 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.
\fI\%ncurses checks the \fITERM\fP environment variable for these.
For other special cases, you should set this environment variable.
Doing this tells \fI\%ncurses\fP 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.
.PP
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\*(''.
.PP
As an alternative to the environment variable,
\fI\%ncurses\fP checks for an extended terminfo capability \fBU8\fP.
This is a numeric capability which can be compiled using \fB@TIC@\ \-x\fP.
For example
.PP
.RS 3
.EX
# 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,
.EE
.RE
.PP
The name \*(``U8\*('' is chosen to be two characters,
to permit it to be used by applications that use \fI\%ncurses\fP'
termcap interface.
.SS "\fINCURSES_TRACE\fP"
During initialization, the \fI\%ncurses\fP debugging library
checks the \fI\%NCURSES_TRACE\fP environment variable.
If it is defined,
to a numeric value,
\fI\%ncurses\fP calls the \fBtrace\fP function,
using that value as the argument.
.PP
The argument values, which are defined in \fBcurses.h\fP, provide several
types of information.
When running with traces enabled, your application will write the
file \fBtrace\fP to the current directory.
.PP
See \fBcurs_trace\fP(3X) for more information.
.SS "\fITERM\fP"
Denotes your terminal type.
Each terminal type is distinct, though many are similar.
.PP
\fITERM\fP 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.
.PP
If you set \fITERM\fP 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 (\fBxterm\fP(1) being a rare exception),
terminal emulators which allow you to
specify \fITERM\fP as a parameter or configuration value do
not change their behavior to match that setting.
.SS "\fITERMCAP\fP"
If the \fI\%ncurses\fP library has been configured with \fItermcap\fP
support, \fI\%ncurses\fP will check for a terminal's description in
termcap form if it is not available in the terminfo database.
.PP
The \fI\%TERMCAP\fP environment variable contains
either a terminal description (with newlines stripped out),
or a file name telling where the information denoted by
the \fITERM\fP environment variable exists.
In either case, setting it directs \fI\%ncurses\fP to ignore
the usual place for this information, e.g., /etc/termcap.
.SS "\fITERMINFO\fP"
\fI\%ncurses\fP can be configured to read from multiple terminal
databases.
The \fI\%TERMINFO\fP variable overrides the location for
the default terminal database.
Terminal descriptions (in terminal format) are stored in terminal databases:
.bP
Normally these are stored in a directory tree,
using subdirectories named by the first letter of the terminal names therein.
.IP
This is the scheme used in System V, which legacy Unix systems use,
and the \fI\%TERMINFO\fP variable is used by \fIcurses\fP applications
on those
systems to override the default location of the terminal database.
.IP \(bu 4
If \fI\%ncurses\fP is built to use hashed databases,
then each entry in this list may be the path of a hashed database file, e.g.,
.RS 4
.PP
.RS 4
.EX
/usr/share/terminfo.db
.EE
.RE
.PP
rather than
.PP
.RS 4
.EX
/usr/share/terminfo/
.EE
.RE
.PP
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.
.RE
.bP
If \fI\%ncurses\fP is built with a support for reading termcap files
directly, then an entry in this list may be the path of a termcap file.
.IP \(bu 4
If the \fI\%TERMINFO\fP variable begins with
\*(``hex:\*('' or \*(``b64:\*('',
\fI\%ncurses\fP uses the remainder of that variable as a compiled
terminal description.
You might produce the base64 format using \fBinfocmp\fP(1M):
.RS 4
.PP
.RS 4
.EX
TERMINFO="$(infocmp \-0 \-Q2 \-q)"
export TERMINFO
.EE
.RE
.PP
The compiled description is used if it corresponds to the terminal identified
by the \fITERM\fP variable.
.RE
.PP
Setting \fI\%TERMINFO\fP 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:
.RS 3
.bP
the last terminal database to which \fI\%ncurses\fP wrote,
if any, is searched first
.bP
the location specified by the \fI\%TERMINFO\fP environment variable
.bP
$HOME/.terminfo
.bP
locations listed in the \fI\%TERMINFO_DIRS\fP environment variable
.bP
one or more locations whose names are configured and compiled into the
\fI\%ncurses\fP library, i.e.,
.RS 3
.bP
@TERMINFO_DIRS@ (corresponding to the \fI\%TERMINFO_DIRS\fP variable)
.bP
@TERMINFO@ (corresponding to the \fITERMINFO\fP variable)
.RE
.RE
.SS "\fITERMINFO_DIRS\fP"
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 \fI\%TERMINFO\fP variable.
The list is separated by colons (i.e., ":") on Unix, semicolons on OS/2 EMX.
.PP
There is no corresponding feature in System V terminfo;
it is an extension developed for \fI\%ncurses\fP.
.SS "\fITERMPATH\fP"
If \fI\%TERMCAP\fP does not hold a file name then \fI\%ncurses\fP checks
the \fI\%TERMPATH\fP environment variable.
This is a list of filenames separated by spaces or colons (i.e., ":") on Unix,
semicolons on OS/2 EMX.
.PP
If the \fI\%TERMPATH\fP environment variable is not set,
\fI\%ncurses\fP looks in the files
.PP
.RS 4
.EX
/etc/termcap, /usr/share/misc/termcap and $HOME/.termcap,
.EE
.RE
.PP
in that order.
.PP
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:
.PP
.RS 4
.EX
$TERMINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.
.EE
.RE
.SH "ALTERNATE CONFIGURATIONS"
Many different
.I \%ncurses
configurations are possible,
determined by the options given to the
.I \%configure
script when building the library.
Run the script with the
.B \-\-help
option to peruse them all.
A few are of particular significance to the application developer
employing
.I \%ncurses.
.TP 5
\-\-disable\-overwrite
The standard include for \fI\%ncurses\fP is as noted in \fBSYNOPSIS\fP:
.RS 5
.PP
.RS 4
.EX
\fB#include <curses.h>\fP
.EE
.RE
.PP
This option is used to avoid filename conflicts when \fI\%ncurses\fP
is not the main implementation of curses of the computer.
If \fI\%ncurses\fP is installed disabling overwrite,
it puts its headers in a subdirectory,
e.g.,
.PP
.RS 4
.EX
\fB#include <ncurses/curses.h>\fP
.EE
.RE
.PP
It also omits a symbolic link which would allow you to use \fB\-lcurses\fP
to build executables.
.RE
.TP 5
\-\-enable\-widec
The configure script renames the library and
(if the \fB\-\-disable\-overwrite\fP 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
.RS 5
.PP
.RS 4
.EX
\fB\-lncurses\fP
.EE
.RE
.PP
you link with
.PP
.RS 4
.EX
\fB\-lncursesw\fP
.EE
.RE
.PP
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:
.bP
Originally, the wide-character feature required the symbol
\fB_XOPEN_SOURCE_EXTENDED\fP
but that was only valid for XPG4 (1996).
.bP
Later, that was deemed conflicting with \fB_XOPEN_SOURCE\fP defined to 500.
.bP
As of mid-2018,
none of the features in this implementation require a \fB_XOPEN_SOURCE\fP
feature greater than 600.
However, X/Open Curses, Issue 7 (2009) recommends defining it to 700.
.bP
Alternatively, you can enable the feature by defining \fBNCURSES_WIDECHAR\fP
with the caveat that some other header file than \fBcurses.h\fP
may require a specific value for \fB_XOPEN_SOURCE\fP
(or a system-specific symbol).
.PP
The \fI\%curses.h\fP 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 \fI\%WINDOW\fP structure differs;
few applications require more than pointers to \fI\%WINDOW\fPs.
.PP
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.
.RE
.TP 5
\-\-with\-pthread
The configure script renames the library.
All of the library names have a \*(``t\*('' appended to them
(before any \*(``w\*('' added by \fB\-\-enable\-widec\fP).
.IP
The global variables such as \fBLINES\fP 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.
.TP 5
\-\-with\-shared
.TP
\-\-with\-normal
.TP
\-\-with\-debug
.TP
\-\-with\-profile
The shared and normal (static) library names differ by their suffixes,
e.g., \fBlibncurses.so\fP and \fBlibncurses.a\fP.
The debug and profiling libraries add a \*(``_g\*(''
and a \*(``_p\*('' to the root names respectively,
e.g., \fBlibncurses_g.a\fP and \fBlibncurses_p.a\fP.
.TP 5
\-\-with\-termlib
Low-level functions which do not depend upon whether the library
supports wide-characters, are provided in the tinfo library.
.IP
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.
.IP
Those functions are described in these pages:
.RS
.bP
\fB\%curs_extend\fP(3X) \- miscellaneous \fIcurses\fP extensions
.bP
\fB\%curs_inopts\fP(3X) \- \fIcurses\fP input options
.bP
\fB\%curs_kernel\fP(3X) \- low-level \fIcurses\fP routines
.bP
\fB\%curs_termattrs\fP(3X) \- \fIcurses\fP environment query routines
.bP
\fB\%curs_termcap\fP(3X) \- \fIcurses\fP emulation of \fItermcap\fP
.bP
\fB\%curs_terminfo\fP(3X) \- \fIcurses\fP interface to \fIterminfo\fP
database
.bP
\fB\%curs_util\fP(3X) \- miscellaneous \fIcurses\fP utility routines
.RE
.TP 5
\-\-with\-trace
The \fBtrace\fP 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.
.SH FILES
.TP
.I @DATADIR@/tabset
tab stop initialization database
.TP
.I \*d
compiled terminal capability database
.SH NOTES
X/Open Curses permits most functions it specifies to be made available
as macros as well.
.\" See X/Open Curses Issue 4, Version 2, pp. 227-234.
.\" See X/Open Curses Issue 7, pp. 311-318.
\fI\%ncurses\fP does so
.bP
for functions that return values via their parameters,
.bP
to support obsolete features,
.bP
to reuse functions
(for example,
those that move the cursor before another operation),
and
.bP
a few special cases.
.PP
If the standard output file descriptor of an
.I \%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.
.PP
See subsection \*(``Header files\*('' below regarding symbols exposed by
inclusion of \fI\%curses.h\fP.
.SH EXTENSIONS
.I \%ncurses
enables an application to capture mouse events on certain terminals,
including
.I \%xterm;
see \fB\%curs_mouse\fP(3X).
.PP
.I \%ncurses
provides a means of responding to window resizing events,
as when running in a GUI terminal emulator application such as
.I \%xterm;
see \fB\%resizeterm\fP(3X) and \fB\%wresize\fP(3X).
.PP
.I \%ncurses
allows an application to query the terminal for the presence of a wide
variety of special keys;
see \fB\%has_key\fP(3X).
.PP
.I \%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
\fB\%define_key\fP(3X),
\fB\%key_defined\fP(3X),
and
\fB\%keyok\fP(3X).
.PP
.I \%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 \fB\%default_colors\fP(3X).
.PP
An
.I \%ncurses
application can choose to hide the internal details of
.I \%WINDOW
structures,
instead using accessor functions such as
\fB\%is_scrollok\fP(3X).
.PP
.I \%ncurses
enables an application to direct application output to a printer
attached to the terminal device;
see \fB\%curs_print\fP(3X).
.PP
.I \%ncurses
offers \fB\%slk_attr\fP(3X) as a counterpart of \fB\%attr_get\fP(3X) for
soft-label key lines,
and \fB\%extended_slk_color\fP(3X) as a form of \fB\%slk_color\fP(3X)
that can gather color information from them when many colors are
supported.
.PP
Some extensions are only available if
.I \%ncurses
is compiled to support them;
see section \*(``ALTERNATE CONFIGURATIONS\*('' above.
.bP
Rudimentary support for multi-threaded applications may be available;
see \fBcurs_threads\fP(3X).
.bP
Functions that ease the management of multiple screens can be exposed;
see \fBcurs_sp_funcs\fP(3X).
.bP
The compiler option
.B \%\-DUSE_GETCAP
causes the library to fall back to reading
.I \%/etc/termcap
if the terminal setup code cannot find a
.I \%term\%info
entry corresponding to
.I TERM.
Use of this feature is not recommended,
as it essentially includes an entire
.I termcap
compiler in the
.I \%ncurses
startup code,
at a cost in memory usage and application launch latency.
.PP
.I \%PDCurses
and NetBSD
.I curses
incorporate some
.I \%ncurses
extensions.
Individual man pages indicate where this is the case.
.SH PORTABILITY
X/Open Curses defines two levels of conformance,
\*(``base\*('' and \*(``enhanced\*(''.
The latter includes several additional features,
such as wide-character and color support.
.I \%ncurses
intends base-level conformance with X/Open Curses,
and supports nearly all its enhanced features.
.\" XXX: What's missing?  GBR counts untic(1), and that's all.
.PP
Differences between X/Open Curses and
.I \%ncurses
are documented in the \*(``PORTABILITY\*('' sections of applicable man
pages.
.SS "Error Checking"
In many cases, X/Open Curses is vague about error conditions,
omitting some of the SVr4 documentation.
.PP
Unlike other implementations, this one checks parameters such as pointers
to \fI\%WINDOW\fP 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.
.SS "Padding Differences"
In historic curses versions, delays embedded in the capabilities \fBcr\fP,
\fBind\fP, \fBcub1\fP, \fBff\fP and \fBtab\fP 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.
.SS "Header Files"
The header file \fI\%curses.h\fP itself includes the header files
\fI\%stdio.h\fP and \fI\%unctrl.h\fP.
.PP
X/Open Curses has more to say,
but does not finish the story:
.RS 4
.PP
The inclusion of <curses.h> may make visible all symbols
from the headers <stdio.h>, <term.h>, <termios.h>, and <wchar.h>.
.RE
.PP
Here is a more complete story:
.bP
Starting with BSD curses, all implementations have included <stdio.h>.
.IP
BSD curses included <curses.h> and <unctrl.h> from an internal header
file
.I \%curses.ext
(\*(``ext\*('' abbreviated \*(``externs\*('').
.IP
BSD curses used <stdio.h> internally (for \fBprintw\fP and \fBscanw\fP),
but nothing in <curses.h> itself relied upon <stdio.h>.
.bP
SVr2 curses added \fBnewterm\fP(3X), which relies upon <stdio.h>.
That is, the function prototype uses \fBFILE\fP.
.IP
SVr4 curses added \fBputwin\fP and \fBgetwin\fP, which also use <stdio.h>.
.IP
X/Open Curses documents all three of these functions.
.IP
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.
.IP
As a result, standard <curses.h> will always include <stdio.h>.
.bP
X/Open Curses is inconsistent with respect to SVr4 regarding <unctrl.h>.
.IP
As noted in \fBcurs_util\fP(3X),
\fI\%ncurses\fP includes <unctrl.h> from <curses.h>
(like SVr4).
.bP
X/Open's comments about <term.h> and <termios.h> may refer to HP-UX and AIX:
.IP
HP-UX curses includes <term.h> from <curses.h>
to declare \fBsetupterm\fP in curses.h,
but \fI\%ncurses\fP (and Solaris curses) do not.
.IP
AIX curses includes <term.h> and <termios.h>.
Again, \fI\%ncurses\fP (and Solaris curses) do not.
.bP
X/Open says that <curses.h> \fImay\fP include <term.h>,
but there is no requirement that it do that.
.IP
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>.
.IP
Because \fI\%ncurses\fP header files include the headers needed to
define datatypes used in the headers,
\fI\%ncurses\fP header files can be included in any order.
But for portability, you should include <curses.h> before <term.h>.
.bP
X/Open Curses says \fI"may make visible"\fP
because including a header file does not necessarily make all symbols
in it visible (there are ifdef's to consider).
.IP
For instance, in \fI\%ncurses\fP <wchar.h> \fImay\fP be included if
the proper symbol is defined, and if \fI\%ncurses\fP is configured for
wide-character support.
If the header is included, its symbols may be made visible.
That depends on the value used for \fB_XOPEN_SOURCE\fP
feature test macro.
.bP
X/Open Curses documents one required header,
in a special case: <stdarg.h> before <curses.h> to prototype
the \fBvw_printw\fP and \fBvw_scanw\fP functions
(as well as the obsolete
the \fBvwprintw\fP and \fBvwscanw\fP functions).
Each of those uses a \fBva_list\fP parameter.
.IP
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 \fBvoid*\fP for the \fBva_list\fP
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>.
.IP
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 \fI\%ncurses\fP)
include <stdarg.h> directly to provide a portable interface.
.SH AUTHORS
Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey.
Based on \fIpcurses\fP by Pavel Curtis.
.SH SEE ALSO
\fB\%curs_variables\fP(3X),
\fB\%terminfo\fP(5),
\fB\%user_caps\fP(5)