ncurses.3x

ncurses-5.4

.SH RETURN VALUE
Routines that return an integer return \fBERR\fR upon failure and an
integer value other than \fBERR\fR upon successful completion, unless
otherwise noted in the routine descriptions.
.PP
All macros return the value of the \fBw\fR version, except \fBsetscrreg\fR,
\fBwsetscrreg\fR, \fBgetyx\fR, \fBgetbegyx\fR, and \fBgetmaxyx\fR.  The return
values of \fBsetscrreg\fR, \fBwsetscrreg\fR, \fBgetyx\fR, \fBgetbegyx\fR, and
\fBgetmaxyx\fR are undefined (i.e., these should not be used as the
right-hand side of assignment statements).
.PP
Routines that return pointers return \fBNULL\fR on error.
.SH ENVIRONMENT
The following environment symbols are useful for customizing the
runtime behavior of the \fBncurses\fR library.  The most important
ones have been already discussed in detail.
.TP 5
BAUDRATE
The debugging library checks this environment symbol when the application
has redirected output to a file.
The symbol's numeric value is used for the baudrate.
If no value is found, \fBncurses\fR uses 9600.
This allows testers to construct repeatable test-cases
that take into account costs that depend on baudrate.
.TP 5
CC
When set, change occurrences of the command_character
(i.e., the \fBcmdch\fP capability)
of the loaded terminfo entries to the value of this symbol.
Very few terminfo entries provide this feature.
.TP 5
COLUMNS
Specify the width of the screen in characters.
Applications running in a windowing environment usually are able to
obtain the width of the window in which they are executing.
If neither the $COLUMNS value nor the terminal's screen size is available,
\fBncurses\fR uses the size which may be specified in the terminfo database
(i.e., the \fBcols\fR capability).
.IP
It is important that your application use a correct size for the screen.
However, 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.
.IP
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, \fBlines\fR and \fBcols\fR should not be specified in
a terminal description for terminals which are run as emulations.
.IP
Use the \fBuse_env\fR function to disable this feature.
.TP 5
ESCDELAY
Specifies the total time, in milliseconds, for which ncurses will
await a character sequence, e.g., a function key.
The default value, 1000 milliseconds, is enough for most uses.
However, it is made a variable to accommodate unusual applications.
.IP
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.
.IP
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.
.TP 5
HOME
Tells \fBncurses\fR where your home directory is.
That is where it may read and write auxiliary terminal descriptions:
.IP
$HOME/.termcap
.br
$HOME/.terminfo
.TP 5
LINES
Like COLUMNS, specify the height of the screen in characters.
See COLUMNS for a detailed description.
.TP 5
MOUSE_BUTTONS_123
This applies only to the OS/2 EMX port.
It specifies the order of buttons on the mouse.
OS/2 numbers a 3-button mouse inconsistently from other
platforms:
.sp
1 = left
.br
2 = right
.br
3 = middle.
.sp
This symbol lets you customize the mouse.
The symbol must be three numeric digits 1-3 in any order, e.g., 123 or 321.
If it is not specified, \fBncurses\fR uses 132.
.TP 5
NCURSES_ASSUMED_COLORS
Override the compiled-in assumption that the
terminal's default colors are white-on-black
(see \fBassume_default_colors\fR(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 \fBmax_colors\fR value is allowed.
.TP 5
NCURSES_NO_PADDING
Most of the terminal descriptions in the terminfo database are written
for real "hardware" terminals.
Many people use terminal emulators
which run in a windowing environment and use curses-based applications.
Terminal emulators can duplicate
all of the important aspects of a hardware terminal, but they do not
have the same limitations.
The chief limitation of a hardware terminal from the standpoint
of your application is the management of dataflow, i.e., timing.
Unless a hardware terminal is interfaced into a terminal concentrator
(which does flow control),
it (or your application) must manage dataflow, preventing overruns.
The cheapest solution (no hardware cost)
is for your program to do this by pausing after
operations that the terminal does slowly, such as clearing the display.
.IP
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.
.IP
Set the NCURSES_NO_PADDING symbol to disable all but mandatory
padding.  Mandatory padding is used as a part of special control
sequences such as \fIflash\fR.
.TP 5
NCURSES_NO_SETBUF
Normally \fBncurses\fR enables buffered output during terminal initialization.
This is done (as in SVr4 curses) for performance reasons.
For testing purposes, both of \fBncurses\fR and certain applications,
this feature is made optional.  Setting the NCURSES_NO_SETBUF variable
disables output buffering, leaving the output in the original (usually
line buffered) mode.
.TP 5
NCURSES_TRACE
During initialization, the \fBncurses\fR debugging library
checks the NCURSES_TRACE symbol.
If it is defined, to a numeric value, \fBncurses\fR calls the \fBtrace\fR
function, using that value as the argument.
.IP
The argument values, which are defined in \fBcurses.h\fR, provide several
types of information.
When running with traces enabled, your application will write the
file \fBtrace\fR to the current directory.
.TP 5
TERM
Denotes your terminal type.
Each terminal type is distinct, though many are similar.
.TP 5
TERMCAP
If the \fBncurses\fR library has been configured with \fItermcap\fR
support, \fBncurses\fR will check for a terminal's description in
termcap form if it is not available in the terminfo database.
.IP
The TERMCAP symbol contains either a terminal description (with
newlines stripped out),
or a file name telling where the information denoted by the TERM symbol exists.
In either case, setting it directs \fBncurses\fR to ignore
the usual place for this information, e.g., /etc/termcap.
.TP 5
TERMINFO
Overrides the directory in which \fBncurses\fR searches for your terminal
description.
This is the simplest, but not the only way to change the list of directories.
The complete list of directories in order follows:
.RS
.TP 3
-
the last directory to which \fBncurses\fR wrote, if any, is searched first
.TP 3
-
the directory specified by the TERMINFO symbol
.TP 3
-
$HOME/.terminfo
.TP 3
-
directories listed in the TERMINFO_DIRS symbol
.TP 3
-
one or more directories whose names are configured and compiled into the
ncurses library, e.g.,
@TERMINFO@
.RE
.TP 5
TERMINFO_DIRS
Specifies a list of directories to search for terminal descriptions.
The list is separated by colons (i.e., ":") on Unix, semicolons on OS/2 EMX.
All of the terminal descriptions are in terminfo form, which makes
a subdirectory named for the first letter of the terminal names therein.
.TP 5
TERMPATH
If TERMCAP does not hold a file name then \fBncurses\fR checks
the TERMPATH symbol.
This is a list of filenames separated by spaces or colons (i.e., ":") on Unix, semicolons on OS/2 EMX.
If the TERMPATH symbol is not set, \fBncurses\fR looks in the files
/etc/termcap, /usr/share/misc/termcap and $HOME/.termcap, 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:
$TERMINFO, $TERMINFO_DIRS, $TERMPATH, as well as $HOME.
.SH FILES
.TP 5
@DATADIR@/tabset
directory containing initialization files for the terminal capability database
@TERMINFO@
terminal capability database
.SH SEE ALSO
\fBterminfo\fR(\*n) and related pages whose names begin "curs_" for detailed routine
descriptions.
.SH EXTENSIONS
The \fBncurses\fR library can be compiled with an option (\fB\-DUSE_GETCAP\fR)
that falls back to the old-style /etc/termcap file if the terminal setup code
cannot find a terminfo entry corresponding to \fBTERM\fR.  Use of this feature
is not recommended, as it essentially includes an entire termcap compiler in
the \fBncurses\fR startup code, at significant cost in core and startup cycles.
.PP
The \fBncurses\fR library includes facilities for capturing mouse events on
certain terminals (including xterm). See the \fBcurs_mouse\fR(3X)
manual page for details.
.PP
The \fBncurses\fR library includes facilities for responding to window
resizing events, e.g., when running in an xterm.
See the \fBresizeterm\fR(3X)
and \fBwresize\fR(3X) manual pages for details.
In addition, the library may be configured with a SIGWINCH handler.
.PP
The \fBncurses\fR 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 \fBdefine_key\fR(3X)
\fBkey_defined\fR(3X),
and \fBkeyok\fR(3X) manual pages for details.
.PP
The \fBncurses\fR 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 \fBdefault_colors\fR(3X) manual page for details.
.PP
The \fBncurses\fR library includes a function for directing application output
to a printer attached to the terminal device.  See the \fBcurs_print\fR(3X)
manual page for details.
.SH PORTABILITY
The \fBncurses\fR library is intended to be BASE-level conformant with the XSI
Curses standard.  The EXTENDED XSI Curses functionality
(including color support) is supported.
.PP
A small number of local differences (that is, individual differences between
the XSI Curses and \fBncurses\fR calls) are described in \fBPORTABILITY\fR
sections of the library man pages.
.PP
The routine \fBhas_key\fR is not part of XPG4, nor is it present in SVr4.  See
the \fBcurs_getch\fR(3X) manual page for details.
.PP
The routine \fBslk_attr\fR is not part of XPG4, nor is it present in SVr4.  See
the \fBcurs_slk\fR(3X) manual page for details.
.PP
The routines \fBgetmouse\fR, \fBmousemask\fR, \fBungetmouse\fR,
\fBmouseinterval\fR, and \fBwenclose\fR relating to mouse interfacing are not
part of XPG4, nor are they present in SVr4.  See the \fBcurs_mouse\fR(3X)
manual page for details.
.PP
The routine \fBmcprint\fR was not present in any previous curses
implementation.  See the \fBcurs_print\fR(3X) manual page for details.
.PP
The routine \fBwresize\fR is not part of XPG4, nor is it present in SVr4.  See
the \fBwresize\fR(3X) manual page for details.
.PP
In historic curses versions, delays embedded in the capabilities \fBcr\fR,
\fBind\fR, \fBcub1\fR, \fBff\fR and \fBtab\fR activated corresponding delay
bits in the UNIX tty driver.  In this implementation, all padding is done by
NUL sends.  This method is slightly more expensive, but narrows the interface
to the UNIX kernel significantly and increases the package's portability
correspondingly.
.SH NOTES
The header file \fB<curses.h>\fR automatically includes the header files
\fB<stdio.h>\fR and \fB<unctrl.h>\fR.
.PP
If standard output from a \fBncurses\fR 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.
.SH AUTHORS
Zeyd M. Ben-Halim, Eric S. Raymond, Thomas E. Dickey.
Based on pcurses by Pavel Curtis.
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