The ncurses library routines give the user a terminal-independent
method of updating character screens with reasonable
optimization. This implementation is “new curses” (ncurses) and
is the approved replacement for 4.4BSD classic curses, which has
been discontinued. This describes ncurses version
@NCURSES_MAJOR@.@NCURSES_MINOR@ (patch @NCURSES_PATCH@).
The ncurses library emulates the curses library of System V
Release 4 UNIX, and XPG4 (X/Open Portability Guide) curses (also
known as XSI curses). XSI stands for X/Open System Interfaces
Extension. The ncurses library is freely redistributable in
source form. Differences from the SVr4 curses are summarized
under the EXTENSIONS and PORTABILITY sections below and described
in detail in the respective EXTENSIONS, PORTABILITY and BUGS
sections of individual man pages.
The ncurses library also provides many useful extensions, i.e.,
features which cannot be implemented by a simple add-on library
but which require access to the internals of the library.
A program using these routines must be linked with the -lncurses
option, or (if it has been generated) with the debugging library
-lncurses_g. (Your system integrator may also have installed
these libraries under the names -lcurses and -lcurses_g.) The
ncurses_g library generates trace logs (in a file called 'trace'
in the current directory) that describe curses actions. See also
the section on ALTERNATE CONFIGURATIONS.
The ncurses package supports: overall screen, window and pad
manipulation; output to windows and pads; reading terminal input;
control over terminal and curses input and output options;
environment query routines; color manipulation; use of soft label
keys; terminfo capabilities; and access to low-level terminal-
The library uses the locale which the calling program has
initialized. That is normally done with setlocale:
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
The function initscr or newterm must be called to initialize the
library before any of the other routines that deal with windows
and screens are used. The routine endwin(3X) must be called
To get character-at-a-time input without echoing (most
interactive, screen oriented programs want this), the following
sequence should be used:
initscr(); cbreak(); noecho();
Most programs would additionally use the sequence:
intrflush(stdscr, FALSE);keypad(stdscr, TRUE);
Before a curses program is run, the tab stops of the terminal
should be set and its initialization strings, if defined, must be
output. This can be done by executing the @TPUT@ init command
after the shell environment variable TERM has been exported.
@TSET@(1) is usually responsible for doing this. [See
terminfo(5) for further details.]
The ncurses library permits manipulation of data structures,
called windows, which can be thought of as two-dimensional arrays
of characters representing all or part of a CRT screen. A
default window called stdscr, which is the size of the terminal
screen, is supplied. Others may be created with newwin.
Note that curses does not handle overlapping windows, that's done
by the panel(3X) library. This means that you can either use
stdscr or divide the screen into tiled windows and not using
stdscr at all. Mixing the two will result in unpredictable, and
Windows are referred to by variables declared as WINDOW *. These
data structures are manipulated with routines described here and
elsewhere in the ncurses manual pages. Among those, the most
basic routines are move and addch. More general versions of
these routines are included with names beginning with w, allowing
the user to specify a window. The routines not beginning with w
After using routines to manipulate a window, refresh(3X) is
called, telling curses to make the user's CRT screen look like
stdscr. The characters in a window are actually of type chtype,
(character and attribute data) so that other information about
the character may also be stored with each character.
Special windows called pads may also be manipulated. These are
windows which are not constrained to the size of the screen and
whose contents need not be completely displayed. See
curs_pad(3X) for more information.
In addition to drawing characters on the screen, video attributes
and colors may be supported, causing the characters to show up in
such modes as underlined, in reverse video, or in color on
terminals that support such display enhancements. Line drawing
characters may be specified to be output. On input, curses is
also able to translate arrow and function keys that transmit
escape sequences into single values. The video attributes, line
drawing characters, and input values use names, defined in
<curses.h>, such as A_REVERSE, ACS_HLINE, and KEY_LEFT.
If the environment variables LINES and COLUMNS are set, or if the
program is executing in a window environment, line and column
information in the environment will override information read by
terminfo. This would affect a program running in an AT&T 630
layer, for example, where the size of a screen is changeable (see
If the environment variable TERMINFO is defined, any program
using curses checks for a local terminal definition before
checking in the standard place. For example, if TERM is set to
att4424, then the compiled terminal definition is found in
(The a is copied from the first letter of att4424 to avoid
creation of huge directories.) However, if TERMINFO is set to
$HOME/myterms, curses first checks
and if that fails, it then checks
This is useful for developing experimental definitions or when
write permission in @TERMINFO@ is not available.
The integer variables LINES and COLS are defined in <curses.h>
and will be filled in by initscr with the size of the screen.
The constants TRUE and FALSE have the values 1 and 0,
The curses routines also define the WINDOW * variable curscr
which is used for certain low-level operations like clearing and
redrawing a screen containing garbage. The curscr can be used in
only a few routines.
Routine and Argument Names
Many curses routines have two or more versions. The routines
prefixed with w require a window argument. The routines prefixed
with p require a pad argument. Those without a prefix generally
The routines prefixed with mv require a y and x coordinate to
move to before performing the appropriate action. The mv
routines imply a call to move before the call to the other
routine. The coordinate y always refers to the row (of the
window), and x always refers to the column. The upper left-hand
corner is always (0,0), not (1,1).
The routines prefixed with mvw take both a window argument and x
and y coordinates. The window argument is always specified
before the coordinates.
In each case, win is the window affected, and pad is the pad
affected; win and pad are always pointers to type WINDOW.
Option setting routines require a Boolean flag bf with the value
TRUE or FALSE; bf is always of type bool. Most of the data types
used in the library routines, such as WINDOW, SCREEN, bool, and
chtype are defined in <curses.h>. Types used for the terminfo
routines such as TERMINAL are defined in <term.h>.
This manual page describes functions which may appear in any
configuration of the library. There are two common
configurations of the library:
the “normal” library, which handles 8-bit characters.
The normal (8-bit) library stores characters combined
with attributes in chtype data.
Attributes alone (no corresponding character) may be
stored in chtype or the equivalent attr_t data. In
either case, the data is stored in something like an
Each cell (row and column) in a WINDOW is stored as a
the so-called “wide” library, which handles multibyte
characters (see the section on ALTERNATE CONFIGURATIONS).
The “wide” library includes all of the calls from the
“normal” library. It adds about one third more calls
using data types which store multibyte characters:
corresponds to chtype. However it is a structure,
because more data is stored than can fit into an
integer. The characters are large enough to require
a full integer value - and there may be more than
one character per cell. The video attributes and
color are stored in separate fields of the
Each cell (row and column) in a WINDOW is stored as
The setcchar(3X) and getcchar(3X) functions store
and retrieve the data from a cchar_t structure.
stores a “wide” character. Like chtype, this may be
stores a wchar_t or WEOF - not the same, though both
may have the same size.
The “wide” library provides new functions which are
analogous to functions in the “normal” library. There is
a naming convention which relates many of the normal/wide
variants: a “_w” is inserted into the name. For example,
waddch becomes wadd_wch.
Routine Name Index
The following table lists the curses routines provided in the
“normal” and “wide” libraries and the names of the manual pages
on which they are described. Routines flagged with “*” are
ncurses-specific, not described by XPG4 or present in SVr4.
curses Routine Name Manual Page Name
Depending on the configuration, additional sets of functions may
curs_memleaks(3X) - curses memory-leak checking
curs_sp_funcs(3X) - curses screen-pointer extension
curs_threads(3X) - curses thread support
curs_trace(3X) - curses debugging routines
Routines that return an integer return ERR upon failure and an
integer value other than ERR upon successful completion, unless
otherwise noted in the routine descriptions.
As a general rule, routines check for null pointers passed as
parameters, and handle this as an error.
All macros return the value of the w version, except setscrreg,
wsetscrreg, getyx, getbegyx, and getmaxyx. The return values of
setscrreg, wsetscrreg, getyx, getbegyx, and getmaxyx are
undefined (i.e., these should not be used as the right-hand side
of assignment statements).
Functions with a “mv” prefix first perform a cursor movement
using wmove, and return an error if the position is outside the
window, or if the window pointer is null. Most “mv”-prefixed
functions (except variadic functions such as mvprintw) are
provided both as macros and functions.
Routines that return pointers return NULL on error.
The following environment symbols are useful for customizing the
runtime behavior of the ncurses library. The most important ones
have been already discussed in detail.
When set, change occurrences of the command_character (i.e., the
cmdch capability) of the loaded terminfo entries to the value of
this variable. Very few terminfo entries provide this feature.
Because this name is also used in development environments to
represent the C compiler's name, ncurses ignores it if it does
not happen to be a single character.
The debugging library checks this environment variable when the
application has redirected output to a file. The variable's
numeric value is used for the baudrate. If no value is found,
ncurses uses 9600. This allows testers to construct repeatable
test-cases that take into account costs that depend on baudrate.
Specify the width of the screen in characters. Applications
running in a windowing environment usually are able to obtain the
width of the window in which they are executing. If neither the
COLUMNS value nor the terminal's screen size is available,
ncurses uses the size which may be specified in the terminfo
database (i.e., the cols capability).
It is important that your application use a correct size for the
screen. This is not always possible because your application may
be running on a host which does not honor NAWS (Negotiations
About Window Size), or because you are temporarily running as
another user. However, setting COLUMNS and/or LINES overrides
the library's use of the screen size obtained from the operating
Either COLUMNS or LINES symbols may be specified independently.
This is mainly useful to circumvent legacy misfeatures of
terminal descriptions, e.g., xterm which commonly specifies a 65
line screen. For best results, lines and cols should not be
specified in a terminal description for terminals which are run
Use the use_env function to disable all use of external
environment (but not including system calls) to determine the
screen size. Use the use_tioctl function to update COLUMNS or
LINES to match the screen size obtained from system calls or the
Specifies the total time, in milliseconds, for which ncurses will
await a character sequence, e.g., a function key. The default
value, 1000 milliseconds, is enough for most uses. However, it
is made a variable to accommodate unusual applications.
The most common instance where you may wish to change this value
is to work with slow hosts, e.g., running on a network. If the
host cannot read characters rapidly enough, it will have the same
effect as if the terminal did not send characters rapidly enough.
The library will still see a timeout.
Note that xterm mouse events are built up from character
sequences received from the xterm. If your application makes
heavy use of multiple-clicking, you may wish to lengthen this
default value because the timeout applies to the composed multi-
click event as well as the individual clicks.
In addition to the environment variable, this implementation
provides a global variable with the same name. Portable
applications should not rely upon the presence of ESCDELAY in
either form, but setting the environment variable rather than the
global variable does not create problems when compiling an
Tells ncurses where your home directory is. That is where it may
read and write auxiliary terminal descriptions:
Like COLUMNS, specify the height of the screen in characters.
See COLUMNS for a detailed description.
This applies only to the OS/2 EMX port. It specifies the order
of buttons on the mouse. OS/2 numbers a 3-button mouse
inconsistently from other platforms:
1 = left
2 = right
3 = middle.
This variable lets you customize the mouse. The variable must be
three numeric digits 1-3 in any order, e.g., 123 or 321. If it
is not specified, ncurses uses 132.
Override the compiled-in assumption that the terminal's default
colors are white-on-black (see default_colors(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 ncurses to not assume anything about the colors,
set this to "-1,-1". To make it green-on-black, set it to "2,0".
Any positive value from zero to the terminfo max_colors value is
This applies only to the MinGW port of ncurses.
The Console2 program's handling of the Microsoft Console API call
CreateConsoleScreenBuffer is defective. Applications which use
this will hang. However, it is possible to simulate the action
of this call by mapping coordinates, explicitly saving and
restoring the original screen contents. Setting the environment
variable NCGDB has the same effect.
This applies only to ncurses configured to use the GPM interface.
If present, the environment variable is a list of one or more
terminal names against which the TERM environment variable is
matched. Setting it to an empty value disables the GPM
interface; using the built-in support for xterm, etc.
If the environment variable is absent, ncurses will attempt to
open GPM if TERM contains “linux”.
NCURSES_NO_HARD_TABSNcurses may use tabs as part of the cursor movement optimization.
In some cases, your terminal driver may not handle these
properly. Set this environment variable to disable the feature.
You can also adjust your stty settings to avoid the problem.
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.
Most of the terminal descriptions in the terminfo database are
written for real “hardware” terminals. Many people use terminal
emulators which run in a windowing environment and use curses-
based applications. Terminal emulators can duplicate all of the
important aspects of a hardware terminal, but they do not have
the same limitations. The chief limitation of a hardware
terminal from the standpoint of your application is the
management of dataflow, i.e., timing. Unless a hardware terminal
is interfaced into a terminal concentrator (which does flow
control), it (or your application) must manage dataflow,
preventing overruns. The cheapest solution (no hardware cost) is
for your program to do this by pausing after operations that the
terminal does slowly, such as clearing the display.
As a result, many terminal descriptions (including the vt100)
have delay times embedded. You may wish to use these
descriptions, but not want to pay the performance penalty.
Set the NCURSES_NO_PADDING environment variable to disable all
but mandatory padding. Mandatory padding is used as a part of
special control sequences such as flash.
This setting is obsolete. Before changes
• started with 5.9 patch 20120825 and
• continued though 5.9 patch 20130126
ncurses enabled buffered output during terminal initialization.
This was done (as in SVr4 curses) for performance reasons. For
testing purposes, both of ncurses and certain applications, this
feature was made optional. Setting the NCURSES_NO_SETBUF
variable disabled output buffering, leaving the output in the
original (usually line buffered) mode.
In the current implementation, ncurses performs its own buffering
and does not require this workaround. It does not modify the
buffering of the standard output.
The reason for the change was to make the behavior for interrupts
and other signals more robust. One drawback is that certain
nonconventional programs would mix ordinary stdio calls with
ncurses calls and (usually) work. This is no longer possible
since ncurses is not using the buffered standard output but its
own output (to the same file descriptor). As a special case, the
low-level calls such as putp still use the standard output. But
high-level curses calls do not.
During initialization, the ncurses library checks for special
cases where VT100 line-drawing (and the corresponding alternate
character set capabilities) described in the terminfo are known
to be missing. Specifically, when running in a UTF-8 locale, the
Linux console emulator and the GNU screen program ignore these.
Ncurses checks the TERM environment variable for these. For
other special cases, you should set this environment variable.
Doing this tells ncurses to use Unicode values which correspond
to the VT100 line-drawing glyphs. That works for the special
cases cited, and is likely to work for terminal emulators.
When setting this variable, you should set it to a nonzero value.
Setting it to zero (or to a nonnumber) disables the special check
for “linux” and “screen”.
As an alternative to the environment variable, ncurses checks for
an extended terminfo capability U8. This is a numeric capability
which can be compiled using @TIC@ -x. For example
# linux console, if patched to provide working
# VT100 shift-in/shift-out, with corresponding font.
linux-vt100|linux console with VT100 line-graphics,
# uxterm with vt100Graphics resource set to false
xterm-utf8|xterm relying on UTF-8 line-graphics,
The name “U8” is chosen to be two characters, to permit it to be
used by applications that use ncurses' termcap interface.
During initialization, the ncurses debugging library checks the
NCURSES_TRACE environment variable. If it is defined, to a
numeric value, ncurses calls the trace function, using that value
as the argument.
The argument values, which are defined in curses.h, provide
several types of information. When running with traces enabled,
your application will write the file trace to the current
See curs_trace(3X) for more information.
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
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 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.
TERMINFOncurses can be configured to read from multiple terminal
databases. The TERMINFO variable overrides the location for the
default terminal database. Terminal descriptions (in terminal
format) are stored in terminal databases:
• Normally these are stored in a directory tree, using
subdirectories named by the first letter of the terminal
This is the scheme used in System V, which legacy Unix
systems use, and the TERMINFO variable is used by curses
applications on those systems to override the default
location of the terminal database.
• If ncurses is built to use hashed databases, then each entry
in this list may be the path of a hashed database file, e.g.,
The hashed database uses less disk-space and is a little
faster than the directory tree. However, some applications
assume the existence of the directory tree, reading it
directly rather than using the terminfo library calls.
• If ncurses is built with a support for reading termcap files
directly, then an entry in this list may be the path of a
• 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
TERMINFO="$(infocmp -0 -Q2 -q)"
The compiled description is used if it corresponds to the
terminal identified by the TERM variable.
Setting TERMINFO is the simplest, but not the only way to set
location of the default terminal database. The complete list of
database locations in order follows:
• the last terminal database to which ncurses wrote, if any,
is searched first
• the location specified by the TERMINFO environment
• locations listed in the TERMINFO_DIRS environment variable
• one or more locations whose names are configured and
compiled into the ncurses library, i.e.,
• @TERMINFO_DIRS@ (corresponding to the TERMINFO_DIRS
• @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
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
If the TERMPATH environment variable is not set, ncurses looks in
/etc/termcap, /usr/share/misc/termcap and $HOME/.termcap,
in that order.
The library may be configured to disregard the following
variables when the current user is the superuser (root), or if
the application uses setuid or setgid permissions:
$TERMINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.
Several different configurations are possible, depending on the
configure script options used when building ncurses. There are a
few main options whose effects are visible to the applications
developer using ncurses:
The standard include for ncurses is as noted in SYNOPSIS:
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.,
It also omits a symbolic link which would allow you to use
-lcurses to build executables.
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
you link with
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,
• Originally, the wide-character feature required the
symbol _XOPEN_SOURCE_EXTENDED but that was only valid
for XPG4 (1996).
• Later, that was deemed conflicting with _XOPEN_SOURCE
defined to 500.
• As of mid-2018, none of the features in this
implementation require a _XOPEN_SOURCE feature greater
than 600. However, X/Open Curses, Issue 7 (2009)
recommends defining it to 700.
• Alternatively, you can enable the feature by defining
NCURSES_WIDECHAR with the caveat that some other header
file than curses.h may require a specific value for
_XOPEN_SOURCE (or a system-specific symbol).
The curses.h file which is installed for the wide-character
library is designed to be compatible with the normal
library's header. Only the size of the WINDOW structure
differs, and very few applications require more than a
pointer to WINDOWs.
If the headers are installed allowing overwrite, the wide-
character library's headers should be installed last, to
allow applications to be built using either library from the
same set of headers.
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.
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.
Low-level functions which do not depend upon whether the
library supports wide-characters, are provided in the tinfo
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
Those functions are described in these pages:
• curs_extend(3X) - miscellaneous curses extensions
• curs_inopts(3X) - curses input options
• curs_kernel(3X) - low-level curses routines
• curs_termattrs(3X) - curses environment query routines
• curs_termcap(3X) - curses emulation of termcap
• curs_terminfo(3X) - curses interfaces to terminfo
• curs_util(3X) - miscellaneous curses utility routines
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
The ncurses library can be compiled with an option (-DUSE_GETCAP)
that falls back to the old-style /etc/termcap file if the
terminal setup code cannot find a terminfo entry corresponding to
TERM. Use of this feature is not recommended, as it essentially
includes an entire termcap compiler in the ncurses startup code,
at significant cost in core and startup cycles.
The ncurses library includes facilities for capturing mouse
events on certain terminals (including xterm). See the
curs_mouse(3X) manual page for details.
The ncurses library includes facilities for responding to window
resizing events, e.g., when running in an xterm. See the
resizeterm(3X) and wresize(3X) manual pages for details. In
addition, the library may be configured with a SIGWINCH handler.
The ncurses library extends the fixed set of function key
capabilities of terminals by allowing the application designer to
define additional key sequences at runtime. See the
define_key(3X) key_defined(3X), and keyok(3X) manual pages for
The ncurses library can exploit the capabilities of terminals
which implement the ISO-6429 SGR 39 and SGR 49 controls, which
allow an application to reset the terminal to its original
foreground and background colors. From the users' perspective,
the application is able to draw colored text on a background
whose color is set independently, providing better control over
color contrasts. See the default_colors(3X) manual page for
The ncurses library includes a function for directing application
output to a printer attached to the terminal device. See the
curs_print(3X) manual page for details.
The ncurses library is intended to be BASE-level conformant with
XSI Curses. The EXTENDED XSI Curses functionality (including
color support) is supported.
A small number of local differences (that is, individual
differences between the XSI Curses and ncurses calls) are
described in PORTABILITY sections of the library man pages.
In many cases, X/Open Curses is vague about error conditions,
omitting some of the SVr4 documentation.
Unlike other implementations, this one checks parameters such as
pointers to WINDOW structures to ensure they are not null. The
main reason for providing this behavior is to guard against
programmer error. The standard interface does not provide a way
for the library to tell an application which of several possible
errors were detected. Relying on this (or some other) extension
will adversely affect the portability of curses applications.
Extensions versus portability
Most of the extensions provided by ncurses have not been
standardized. Some have been incorporated into other
implementations, such as PDCurses or NetBSD curses. Here are a
few to consider:
• The routine has_key is not part of XPG4, nor is it present in
SVr4. See the curs_getch(3X) manual page for details.
• The routine slk_attr is not part of XPG4, nor is it present
in SVr4. See the curs_slk(3X) manual page for details.
• The routines getmouse, mousemask, ungetmouse, mouseinterval,
and wenclose relating to mouse interfacing are not part of
XPG4, nor are they present in SVr4. See the curs_mouse(3X)
manual page for details.
• The routine mcprint was not present in any previous curses
implementation. See the curs_print(3X) manual page for
• The routine wresize is not part of XPG4, nor is it present in
SVr4. See the wresize(3X) manual page for details.
• The WINDOW structure's internal details can be hidden from
application programs. See curs_opaque(3X) for the discussion
of is_scrollok, etc.
• This implementation can be configured to provide rudimentary
support for multi-threaded applications. See
curs_threads(3X) for details.
• This implementation can also be configured to provide a set
of functions which improve the ability to manage multiple
screens. See curs_sp_funcs(3X) for details.
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> automatically includes the header
files <stdio.h> and <unctrl.h>.
X/Open Curses has more to say, but does not finish the story:
The inclusion of <curses.h> may make visible all symbols from
the headers <stdio.h>, <term.h>, <termios.h>, and <wchar.h>.
Here is a more complete story:
• Starting with BSD curses, all implementations have included
BSD curses included <curses.h> and <unctrl.h> from an
internal header "curses.ext" ("ext" was a short name for
BSD curses used <stdio.h> internally (for printw and scanw),
but nothing in <curses.h> itself relied upon <stdio.h>.
• SVr2 curses added newterm(3X), which relies upon <stdio.h>.
That is, the function prototype uses FILE.
SVr4 curses added putwin and getwin, which also use
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
• X/Open Curses is inconsistent with respect to SVr4 regarding
As noted in curs_util(3X), ncurses includes <unctrl.h> from
<curses.h> (like SVr4).
• X/Open's comments about <term.h> and <termios.h> may refer to
HP-UX and AIX:
HP-UX curses includes <term.h> from <curses.h> to declare
setupterm in curses.h, but ncurses (and Solaris curses) do
AIX curses includes <term.h> and <termios.h>. Again, ncurses
(and Solaris curses) do not.
• X/Open says that <curses.h> may include <term.h>, but there
is no requirement that it do that.
Some programs use functions declared in both <curses.h> and
<term.h>, and must include both headers in the same module.
Very old versions of AIX curses required including <curses.h>
before including <term.h>.
Because ncurses header files include the headers needed to
define datatypes used in the headers, ncurses header files
can be included in any order. But for portability, you
should include <curses.h> before <term.h>.
• X/Open Curses says "may make visible" because including a
header file does not necessarily make all symbols in it
visible (there are ifdef's to consider).
For instance, in ncurses <wchar.h> may be included if the
proper symbol is defined, and if ncurses is configured for
wide-character support. If the header is included, its
symbols may be made visible. That depends on the value used
for _XOPEN_SOURCE feature test macro.
• X/Open Curses documents one required header, in a special
case: <stdarg.h> before <curses.h> to prototype the vw_printw
and vw_scanw functions (as well as the obsolete the vwprintw
and vwscanw functions). Each of those uses a va_list
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
If standard output from a ncurses program is re-directed to
something which is not a tty, screen updates will be directed to
standard error. This was an undocumented feature of AT&T System
V Release 3 curses.
This page is part of the ncurses (new curses) project.
Information about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have
a bug report for this manual page, send it to
firstname.lastname@example.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2021-08-27. (At
that time, the date of the most recent commit that was found in
the repository was 2021-05-23.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to