|
HTML rendering created 2026-01-16 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | EXTENSIONS | PORTABILITY | HISTORY | SEE ALSO | COLOPHON |
|
|
|
curs_terminfo(3X) Library calls curs_terminfo(3X)
del_curterm, putp, restartterm, set_curterm, setupterm, tigetflag,
tigetnum, tigetstr, tiparm, tiparm_s, tiscan_s, tparm, tputs,
vid_attr, vid_puts, vidattr, vidputs - curses interfaces to term‐
info database
#include <curses.h>
#include <term.h>
TERMINAL * cur_term;
const char * const boolnames[];
const char * const boolcodes[];
const char * const boolfnames[];
const char * const numnames[];
const char * const numcodes[];
const char * const numfnames[];
const char * const strnames[];
const char * const strcodes[];
const char * const strfnames[];
int setupterm(const char * term, int filedes, int * errret);
TERMINAL * set_curterm(TERMINAL * nterm);
int del_curterm(TERMINAL * oterm);
int restartterm(const char * term, int filedes, int * errret);
char * tparm(const char * str, ...);
/* or */
char * tparm(const char * str, long p1 ... long p9);
int tputs(const char * str, int affcnt, int (* putc)(int));
int putp(const char * str);
int vidputs(chtype attrs, int (* putc)(int));
int vidattr(chtype attrs);
int vid_puts(attr_t attrs, short pair, void * opts, int (* putc)(int));
int vid_attr(attr_t attrs, short pair, void * opts);
int tigetflag(const char * cap-code);
int tigetnum(const char * cap-code);
char * tigetstr(const char * cap-code);
char * tiparm(const char * str, ...);
/* extensions */
char * tiparm_s(int expected, int mask, const char * str, ...);
int tiscan_s(int * expected, int * mask, const char * str);
/* deprecated */
int setterm(const char * term);
These lower-level functions of the curses standard must be called
by programs that deal directly with the terminfo database to
handle certain terminal capabilities, such as programming function
keys. For all other functionality, curses functions are more
suitable and their use is recommended.
None of these functions use (or are aware of) multibyte character
strings such as UTF-8.
• Capability names and codes use the POSIX portable character
set.
• Capability string values have no associated encoding; they are
strings of 8-bit characters.
Initialization
Call setupterm from your application to have terminfo manage the
terminal device; this action initializes the terminal-dependent
variables listed in term_variables(3X). (A curses application
calling initscr(3X) or newterm(3X) achieves the same result.)
Applications can use the terminal capabilities either directly, by
object definitions corresponding to capability names and codes
(see term_variables(3X)) or by calling the functions documented
here. setupterm initializes the terminfo variables lines and
columns as described in use_env(3X).
Pass parameterized string capability values through tparm to
instantiate them. All terminfo strings (including the output of
tparm) should be sent to the terminal device with tputs or putp.
Call reset_shell_mode(3X) to restore the terminal modes before
exiting. (A curses application calling endwin(3X) achieves the
same result.)
Programs that use cursor addressing should emit certain
capabilities at specific times. Specifically, output
• enter_ca_mode upon startup, and
• exit_ca_mode before exiting.
Programs that execute shell subprocesses should
• call reset_shell_mode(3X) and output exit_ca_mode before the
shell is called, and
• output enter_ca_mode and call reset_prog_mode(3X) after
returning from the shell.
setupterm reads in the terminfo database, initializing the term‐
info structures, but does not set up the output virtualization
structures used by curses. Its parameters follow.
term is the terminal type, a character string. If term is
null, the environment variable TERM is read.
filedes
is the file descriptor used for getting and setting
terminal I/O modes.
Higher-level applications use newterm(3X) to initialize
the terminal, passing an output stream rather than a
descriptor. In curses, the two are the same because
newterm calls setupterm, passing the file descriptor
derived from its output stream parameter.
errret
points to an optional location where an error status can
be returned to the caller. If errret is not null, then
setupterm returns OK or ERR and stores a status value in
the integer pointed to by errret. A return value of OK
combined with status of 1 in errret is normal.
If ERR is returned, examine errret.
1 means that the terminal is a hard-copy type (lacks
destructive backspace), and cannot be used for curses
applications. The library determines this fact by
checking the terminal type's hardcopy (hc)
capability.
0 means that the terminal could not be found, or that
it is a generic type, having too little information
for curses applications to run.
setupterm determines if the entry is a generic type
by checking the generic_type (gn) capability.
-1 means that the terminfo database could not be found.
If errret is null, setupterm reports an error message upon
finding an error and exits. Thus, the simplest call is:
setupterm((char *) NULL, 1, (int *) NULL);
which uses all the defaults and sends the output to
stdout.
The Terminal State
setupterm stores its information about the terminal in a TERMINAL
structure pointed to by the global variable cur_term. If it
detects an error, or decides that the terminal is unsuitable
(hardcopy or generic), it discards this information, making it
unavailable to applications.
If setupterm is called repeatedly for the same terminal type, it
reuses the information. It maintains only one copy of a given
type's capabilities in memory. If called for different types,
setupterm allocates new storage for each set of terminal
capabilities.
set_curterm sets cur_term to nterm, making all of the terminfo
Boolean, numeric, and string capabilities use the values from
nterm. It returns the old value of cur_term.
del_curterm releases the memory pointed to by oterm. If oterm is
the same as cur_term, references to any of the terminfo Boolean,
numeric, and string capabilities thereafter may refer to invalid
memory locations until setupterm is called again.
restartterm is similar to setupterm, but is intended for use after
restoring program memory to a previous state (for example, when
reloading an application that has been suspended from one terminal
session and restored in another). restartterm assumes that the
display dimensions and the input and output options are the same
as when memory was saved, but the terminal type and line speed may
differ. Accordingly, restartterm saves relevant terminal state,
calls setupterm, then restores that state.
Formatting Output
tparm instantiates the string str with parameters pi. It returns
a pointer to a character string representing str with the
parameters applied to “%” expressions within. Application
developers should keep in mind some quirks of the interface.
• Although tparm's actual parameters may be integers or strings,
the prototype expects long (integer) values.
• Aside from the set_attributes (sgr) capability, most terminal
capabilities require no more than one or two parameters.
• Padding information is ignored by tparm; it is interpreted by
tputs.
• The capability string is null-terminated. Use “\200” where an
ASCII NUL is needed in the output.
tiparm is a newer form of tparm that uses stdarg.h rather than a
fixed-length parameter list. Its numeric parameters are ints
rather than longs.
tparm and tiparm assume that the application passes parameters
consistent with the terminal description. ncurses provides two
extensions as alternatives to deal with untrusted data.
• The tiparm_s extension is a safer formatting function than
tparm or tiparm, because it allows the developer to tell the
curses library how many parameters to expect in the parameter
list, and which may be string parameters.
The mask parameter has one bit set for each of the parameters
(up to 9) passed as char pointers rather than numbers.
• The extension tiscan_s allows the application to inspect a
formatting capability to see what the curses library would
assume.
Output Functions
String capabilities can contain padding, a time delay
(accommodating performance limitations of hardware terminals)
expressed as $<n>, where n is a nonnegative integral count of
milliseconds. If n exceeds 30,000 (thirty seconds), ncurses caps
it at that value.
tputs interprets time delays in the string str and acts upon them.
• The str parameter must be a terminfo string capability or the
return value of tparm or tiparm.
• affcnt is the number of lines affected, or 1 if not
applicable.
• putc is a putchar-like function to which the characters are
passed, one at a time.
tputs processes each time delay with the delay_output(3X)
function, routing any resulting padding characters through this
function.
putp calls “tputs(str, 1, putchar)”. The output of putp always
goes to stdout, rather than the filedes specified in setupterm.
vidputs displays the string on the terminal in the video attribute
mode attrs, which is any combination of the attributes listed in
curses(3X). The characters are passed to the putchar-like
function putc.
vidattr is like vidputs, except that it outputs through
putchar(3).
vid_attr and vid_puts correspond to vidattr and vidputs,
respectively. They use multiple parameters to represent the
character attributes and color; namely,
• attrs, of type attr_t, for the attributes and
• pair, of type short, for the color pair number.
Use the attribute constants prefixed with “WA_” with vid_attr and
vid_puts.
X/Open Curses reserves the opts argument for future use, saying
that applications must provide a null pointer for that argument;
but see section “EXTENSIONS” below.
While putp is a lower-level function that does not use higher-
level curses state, ncurses declares it in curses.h because
System V did so (see section “HISTORY” below).
Terminal Capability Functions
tigetflag, tigetnum, and tigetstr return the value of the
capability corresponding to the terminfo cap-code, such as xenl,
passed to them. The cap-code for each capability is given in the
table column of that name in the “Capabilities” section of
terminfo(5).
These functions return special values to denote errors.
tigetflag returns
-1 if cap-code is not a Boolean capability, or
0 if it is canceled or absent from the terminal description.
tigetnum returns
-2 if cap-code is not a numeric capability, or
-1 if it is canceled or absent from the terminal description.
tigetstr returns
(char *)-1
if cap-code is not a string capability, or
NULL if it is canceled or absent from the terminal description.
Terminal Capability Names
These null-terminated arrays contain
• the short terminfo names (“codes”),
• the termcap names (“names”), and
• the long terminfo names (“fnames”)
for each standard terminfo capability name.
const char *boolnames[], *boolcodes[], *boolfnames[]
const char *numnames[], *numcodes[], *numfnames[]
const char *strnames[], *strcodes[], *strfnames[]
Releasing Memory
Each successful call to setupterm allocates memory to hold the
terminal description. As a side effect, it sets cur_term to point
to this memory. If an application calls
del_curterm(cur_term);
the memory will be freed.
The formatting functions tparm and tiparm extend the storage
allocated by setupterm as follows.
• They add the “static” terminfo variables [a-z]. Before
ncurses 6.3, those were shared by all screens. With ncurses
6.3, those are allocated per screen. See terminfo(5).
• To improve performance, ncurses 6.3 caches the result of
analyzing terminfo strings for their parameter types. That is
stored as a binary tree referenced from the TERMINAL
structure.
The higher-level initscr and newterm functions use setupterm.
Normally they do not free this memory, but it is possible to do
that using the delscreen(3X) function.
Functions that return integers return ERR upon failure and OK upon
success.
In ncurses,
del_curterm
fails if its terminal parameter is null.
putp calls tputs, returning the same error codes.
restartterm
fails if the associated call to setupterm returns ERR.
setupterm
fails if it cannot allocate enough memory, or create the
initial windows (stdscr, curscr, and newscr). Other error
conditions are documented above.
tparm
returns a null pointer if the capability would require
unexpected parameters; that is, too many, too few, or
incorrect types (strings where integers are expected, or vice
versa).
tputs
fails if the string parameter is null. It does not detect
I/O errors: X/Open Curses states that tputs ignores the
return value of the output function putc.
The vid_attr function in ncurses is a special case. It was
originally implemented based on a draft of X/Open Curses, as a
macro, before other parts of the ncurses wide-character API were
developed, and unlike the other wide-character functions, is also
provided in the non-wide-character configuration.
The functions marked as extensions originated in ncurses, and are
not found in SVr4 curses, 4.4BSD curses, or any other previous
curses implementation.
ncurses allows opts to be a pointer to int, which overrides the
pair (short) argument.
Except for setterm, X/Open Curses Issue 4 describes these
functions. It specifies no error conditions for them.
SVr4 describes a successful return value except where “otherwise
noted” as “an integer value other than ERR”.
Header Files
On legacy curses systems, include curses.h and term.h in that
order to make visible the definitions of the string arrays storing
the capability names and codes.
Compatibility Macros
ncurses implements a few macros for early System V curses
compatibility (see section “HISTORY” below). They include crmode,
fixterm, gettmode, nocrmode, resetterm, saveterm, and setterm.
In SVr4, these are found in curses.h, but except for setterm, are
likewise macros. The one function, setterm, is mentioned in the
manual page. It further notes that setterm was replaced by
setupterm, stating that the call
setupterm(term, 1, (int *)0)
provides the same functionality as
setterm(term)
and discouraging the latter for new programs.
Legacy Data
setupterm copies the terminal name to the array ttytype. This
behavior is not specified by X/Open Curses, but is assumed by some
applications.
Other implementations may not declare the capability name arrays.
Some provide them without declaring them. X/Open Curses does not
specify them.
Extended terminal capability names, as defined by “tic -x”, are
not stored in the arrays described here.
Output Buffering
Older versions of ncurses assumed that the file descriptor passed
to setupterm from initscr or newterm used buffered I/O, and wrote
to the corresponding stdio stream. In addition to the limitation
that the terminal was left in block-buffered mode on exit (like
System V curses), it was problematic because ncurses did not allow
a reliable way to clean up on receiving SIGTSTP.
ncurses 6.x uses output buffers managed directly by ncurses. The
lower-level functions described here that write to the terminal
device do so via the standard output stream; they thus are not
signal-safe. The higher-level functions in ncurses employ
alternate versions of these functions using a more reliable
buffering scheme.
Function Prototypes
The X/Open Curses prototypes are based on the SVr4 curses header
declarations, which were defined at the same time the C language
was first standardized in the late 1980s.
• X/Open Curses uses const less effectively than a later design
might, sometimes applying it needlessly to function parameters
that are passed by value (and therefore copied), and in most
cases overlooking parameters that normally would benefit from
const. Passing const-qualified parameters to functions that
do not declare them const may prevent the program from
compiling. On the other hand, “writable strings” are an
obsolescent C language feature.
As an extension, ncurses can be configured to change the
function prototypes to use the const keyword. The ncurses ABI
6 enables this feature by default.
• X/Open Curses prototypes tparm with a fixed number of
parameters, rather than a variable argument list.
ncurses uses a variable argument list, but can be configured
to use the fixed-parameter list. Portable applications should
provide nine parameters after the format; zeroes are fine for
this purpose.
In response to review comments by Thomas E. Dickey, X/Open
Curses Issue 7 proposed the tiparm function in mid-2009.
While tiparm is always provided in ncurses, the older form is
available only as a build-time configuration option. If not
specially configured, tparm is the same as tiparm.
Both forms of tparm have drawbacks.
• Most calls to tparm require only one or two parameters.
Passing nine on each call is awkward.
Using long for the numeric parameter type is a workaround to
make the parameter use the same amount of stack memory as a
pointer. That approach dates to the mid-1980s, before C was
standardized. Since ANSI C (1989), C language standards do
not require a pointer to fit in a long).
• Providing the right number of parameters for a variadic
function such as tiparm can be a problem, in particular for
string parameters. However, only a few terminfo capabilities
use string parameters (for instance, the ones used for
programmable function keys).
The ncurses library checks usage of these capabilities, and
returns ERR if the capability mishandles string parameters.
But it cannot check if a calling program provides strings in
the right places for the tparm calls.
ncurses's tput(1) checks its use of these capabilities with a
table, so that it calls tparm correctly.
Special TERM treatment
If ncurses is configured to use a terminal driver that does not
employ the POSIX termios API, as with the MinGW port,
• setupterm interprets a missing or empty TERM variable as the
special value “unknown”.
SVr4 curses uses the special value “dumb”.
The difference between the two is that the former uses the
generic_type (gn) terminfo capability, while the latter does
not. A generic terminal is unsuitable for full-screen
applications.
• setupterm allows explicit use of the Microsoft Windows console
driver by checking whether the TERM environment variable has
the value “#win32con” or an abbreviation of that string.
Other Portability Issues
In SVr4, set_curterm returns an int, OK or ERR. We have chosen to
implement the X/Open Curses semantics.
In SVr4, the third argument of tputs has the type “int (*)(char)”.
At least one implementation of X/Open Curses (Solaris xcurses)
returns a value other than OK or ERR from tputs. It instead
returns the length of the string, and does no error checking.
Very old versions of AIX curses required inclusion of curses.h
before term.h.
SVr2 (1984) introduced the terminfo feature. Its programming
manual mentioned the following low-level functions.
Function Description
───────────────────────────────────────────────────────────────────
fixterm restore terminal to “in curses” state
gettmode establish current terminal modes
mvcur low level cursor motion
putp use tputs to send characters via putchar
resetterm set terminal modes to “out of curses” state
resetty reset terminal flags to stored value
saveterm save current modes as “in curses” state
savetty store current terminal flags
setterm establish terminal with given type
setupterm establish terminal with given type
tparm interpolate parameters into string capability
tputs apply padding information to a string
vidattr like vidputs, but output through putchar
vidputs write string to terminal, applying specified
attributes
The programming manual also mentioned functions provided for
termcap compatibility (commenting that they “may go away at a
later date”).
Function Description
───────────────────────────────────────────────────────────────────
tgetent look up termcap entry for given name
tgetflag get Boolean entry for given id
tgetnum get numeric entry for given id
tgetstr get string entry for given id
tgoto apply parameters to given capability
tputs write characters via a function parameter, applying
padding
Early terminfo programs obtained capability values from the
TERMINAL structure initialized by setupterm.
SVr3 (1987) extended terminfo by adding functions to retrieve
capability values (like the termcap interface), and reusing tgoto
and tputs.
Function Description
───────────────────────────────────────────────────────────────────
tigetflag get Boolean entry for given id
tigetnum get numeric entry for given id
tigetstr get string entry for given id
SVr3 also replaced several of the SVr2 terminfo functions that had
no counterpart in the termcap interface, documenting them as
obsolete.
Function Replaced by
───────────────────────────────────────────────────────────────────
crmode cbreak
fixterm reset_prog_mode
gettmode n/a
nocrmode nocbreak
resetterm reset_shell_mode
saveterm def_prog_mode
setterm setupterm
SVr3 kept the mvcur, vidattr, and vidputs functions, along with
putp, tparm, and tputs. The latter were needed to support
padding, and to handle capabilities accessed by functions such as
vidattr (which used more than the two parameters supported by
tgoto).
SVr3 introduced the functions for switching between terminal
descriptions; for example, set_curterm. Some changes reflected
incremental improvements to the SVr2 library.
• The TERMINAL type definition was introduced in SVr3.01, for
the term structure provided in SVr2.
• Various global variables such as boolnames were mentioned in
the programming manual at this point, though the variables had
been provided in SVr2.
SVr4 (1989) added the vid_attr and vid_puts functions.
Other low-level functions are declared in the curses header files
of Unix systems, but none are documented. Those noted as
“obsolete” by SVr3 remained in use by System V's vi(1) editor.
curses(3X), curs_initscr(3X), curs_kernel(3X), curs_memleaks(3X),
curs_termcap(3X), curs_variables(3X), putc(3), term_variables(3X),
terminfo(5)
This page is part of the ncurses (new curses) project.
Information about the project can be found at
⟨https://invisible-island.net/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to bug-ncurses@gnu.org.
This page was obtained from the tarball ncurses-6.6.tar.gz fetched
from ⟨https://ftp.gnu.org/gnu/ncurses/⟩ on 2026-01-16. 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 man-pages@man7.org
ncurses @NCURSES_MAJOR@.@NCU... 2025-11-11 curs_terminfo(3X)
|
HTML rendering created 2026-01-16 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|