curs_terminfo(3x) Library calls curs_terminfo(3x)
del_curterm, mvcur, putp, restartterm, set_curterm, setupterm,
tigetflag, tigetnum, tigetstr, tiparm, tiparm_s, tiscan_s, tparm,
tputs, vid_attr, vid_puts, vidattr, vidputs - curses interfaces to
terminfo 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 mvcur(int oldrow, int oldcol, int newrow, int newcol);
int tigetflag(const char *capname);
int tigetnum(const char *capname);
char *tigetstr(const char *capname);
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);
These low-level routines must be called by programs that have to deal
directly with the terminfo database to handle certain terminal capabil-
ities, such as programming function keys. For all other functionality,
curses routines are more suitable and their use is recommended.
None of these functions use (or are aware of) multibyte character
strings such as UTF-8:
o capability names use the POSIX portable character set
o capability string values have no associated encoding; they are
strings of 8-bit characters.
Initially, setupterm should be called. The high-level curses functions
initscr and newterm call setupterm to initialize the low-level set of
terminal-dependent variables [listed in terminfo(5)].
Applications can use the terminal capabilities either directly (via
header definitions), or by special functions. The header files curs-
es.h and term.h should be included (in this order) to get the defini-
tions for these strings, numbers, and flags.
The terminfo variables lines and columns are initialized by setupterm
as follows:
o If use_env(FALSE) has been called, values for lines and columns
specified in terminfo are used.
o Otherwise, if the environment variables LINES and COLUMNS exist,
their values are used. If these environment variables do not exist
and the program is running in a window, the current window size is
used. Otherwise, if the environment variables do not exist, the
values for lines and columns specified in the terminfo database are
used.
Parameterized strings should be passed through tparm to instantiate
them. All terminfo strings (including the output of tparm) should be
printed with tputs or putp. Call reset_shell_mode to restore the tty
modes before exiting [see curs_kernel(3x)].
Programs which use cursor addressing should
o output enter_ca_mode upon startup and
o output exit_ca_mode before exiting.
Programs which execute shell subprocesses should
o call reset_shell_mode and output exit_ca_mode before the shell is
called and
o output enter_ca_mode and call reset_prog_mode after returning from
the shell.
The setupterm routine reads in the terminfo database, initializing the
terminfo structures, but does not set up the output virtualization
structures used by curses. These are its parameters:
term is the terminal type, a character string. If term is null, the
environment variable TERM is used.
filedes
is the file descriptor used for getting and setting terminal
I/O modes.
Higher-level applications use newterm(3x) for initializing the
terminal, passing an output stream rather than a descriptor.
In curses, the two are the same because newterm calls se-
tupterm, passing the file descriptor derived from its output
stream parameter.
errret
points to an optional location where an error status can be re-
turned 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 sta-
tus of 1 in errret is normal.
If ERR is returned, examine errret:
1 means that the terminal is hardcopy, cannot be used for
curses applications.
setupterm determines if the entry is a hardcopy type by
checking the hc (hardcopy) 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 gn (generic_type) capability.
-1 means that the terminfo database could not be found.
If errret is null, setupterm prints an error message upon find-
ing an error and exits. Thus, the simplest call is:
setupterm((char *)0, 1, (int *)0);,
which uses all the defaults and sends the output to stdout.
The setupterm routine 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 not available to
applications.
If setupterm is called repeatedly for the same terminal type, it will
reuse the information. It maintains only one copy of a given termi-
nal's capabilities in memory. If it is called for different terminal
types, setupterm allocates new storage for each set of terminal capa-
bilities.
The set_curterm routine sets cur_term to nterm, and makes all of the
terminfo boolean, numeric, and string variables use the values from
nterm. It returns the old value of cur_term.
The del_curterm routine frees the space pointed to by oterm and makes
it available for further use. If oterm is the same as cur_term, refer-
ences to any of the terminfo boolean, numeric, and string variables
thereafter may refer to invalid memory locations until another se-
tupterm has been called.
The restartterm routine is similar to setupterm and initscr, except
that it is called after restoring memory to a previous state (for exam-
ple, when reloading a game saved as a core image dump). restartterm
assumes that the windows and the input and output options are the same
as when memory was saved, but the terminal type and baud rate may be
different. Accordingly, restartterm saves various tty state bits,
calls setupterm, and then restores the bits.
The tparm routine instantiates the string str with parameters pi. A
pointer is returned to the result of str with the parameters applied.
Application developers should keep in mind these quirks of the inter-
face:
o Although tparm's actual parameters may be integers or strings, the
prototype expects long (integer) values.
o Aside from the set_attributes (sgr) capability, most terminal capa-
bilities require no more than one or two parameters.
o Padding information is ignored by tparm; it is interpreted by
tputs.
o The capability string is null-terminated. Use "\200" where an
ASCII NUL is needed in the output.
tiparm is a newer form of tparm which uses <stdarg.h> rather than a
fixed-parameter list. Its numeric parameters are integers (int) rather
than longs.
Both tparm and tiparm assume that the application passes parameters
consistent with the terminal description. Two extensions are provided
as alternatives to deal with untrusted data:
o tiparm_s is an extension which 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) which will be passed as char* rather than numbers.
o The extension tiscan_s allows the application to inspect a format-
ting capability to see what the curses library would assume.
The tputs routine applies padding information (i.e., by interpreting
marker embedded in the terminfo capability such as "$<5>" as 5 mil-
liseconds) to the string str and outputs it:
o The str parameter must be a terminfo string variable or the return
value from tparm, tiparm, tgetstr, or tgoto.
The tgetstr and tgoto functions are part of the termcap interface,
which happens to share this function name with the terminfo inter-
face.
o affcnt is the number of lines affected, or 1 if not applicable.
o putc is a putchar-like routine to which the characters are passed,
one at a time.
The putp routine calls tputs(str, 1, putchar). The output of putp al-
ways goes to stdout, rather than the filedes specified in setupterm.
The vidputs routine 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 routine
putc.
The vidattr routine is like the vidputs routine, except that it outputs
through putchar.
The vid_attr and vid_puts routines correspond to vidattr and vidputs,
respectively. They use a set of arguments for representing the video
attributes plus color, i.e.,
o attrs of type attr_t for the attributes and
o pair of type short for the color-pair number.
The vid_attr and vid_puts routines are designed to use the attribute
constants with the WA_ prefix.
X/Open Curses reserves the opts argument for future use, saying that
applications must provide a null pointer for that argument. As an ex-
tension, this implementation allows opts to be used as a pointer to
int, which overrides the pair (short) argument.
The mvcur routine provides low-level cursor motion. It takes effect
immediately (rather than at the next refresh). Unlike the other low-
level output functions, which either write to the standard output or
pass an output function parameter, mvcur uses an output file descriptor
derived from the output stream parameter of newterm(3x).
While putp and mvcur are low-level functions which do not use the high-
level curses state, they are declared in <curses.h> because SystemV did
this (see HISTORY).
The tigetflag, tigetnum and tigetstr routines return the value of the
capability corresponding to the terminfo capname passed to them, such
as xenl. The capname for each capability is given in the table column
entitled capname code in the capabilities section of terminfo(5).
These routines return special values to denote errors.
The tigetflag routine returns
-1 if capname is not a boolean capability, or
0 if it is canceled or absent from the terminal description.
The tigetnum routine returns
-2 if capname is not a numeric capability, or
-1 if it is canceled or absent from the terminal description.
The tigetstr routine returns
(char *)-1
if capname is not a string capability, or
0 if it is canceled or absent from the terminal description.
These null-terminated arrays contain
o the short terminfo names ("codes"),
o the termcap names ("names"), and
o the long terminfo names ("fnames")
for each of the predefined terminfo variables:
const char *boolnames[], *boolcodes[], *boolfnames[]
const char *numnames[], *numcodes[], *numfnames[]
const char *strnames[], *strcodes[], *strfnames[]
Each successful call to setupterm allocates memory to hold the terminal
description. As a side-effect, it sets cur_term to point to this memo-
ry. 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:
o 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) for details.
o 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.
Routines that return an integer return ERR upon failure and OK (SVr4
only specifies "an integer value other than ERR") upon successful com-
pletion, unless otherwise noted in the preceding routine descriptions.
Routines that return pointers always return NULL on error.
X/Open defines no error conditions. In this implementation
del_curterm
returns an error if its terminal parameter is null.
putp calls tputs, returning the same error-codes.
restartterm
returns an error if the associated call to setupterm returns an
error.
setupterm
returns an error if it cannot allocate enough memory, or create
the initial windows (stdscr, curscr, newscr). Other error con-
ditions are documented above.
tparm
returns a null if the capability would require unexpected pa-
rameters, e.g., too many, too few, or incorrect types (strings
where integers are expected, or vice versa).
tputs
returns an error if the string parameter is null. It does not
detect I/O errors: X/Open states that tputs ignores the return
value of the output function putc.
This implementation provides a few macros for compatibility with sys-
tems before SVr4 (see HISTORY). Those include crmode, fixterm,
gettmode, nocrmode, resetterm, saveterm, and setterm.
In SVr4, those are found in <curses.h>, but except for setterm, are
likewise macros. The one function, setterm, is mentioned in the manual
page. The manual page notes that the setterm routine was replaced by
setupterm, stating that the call:
setupterm(term, 1, (int *)0)
provides the same functionality as setterm(term), and is not recommend-
ed for new programs. This implementation provides each of those sym-
bols as macros for BSD compatibility,
SVr2 introduced the terminfo feature. Its programming manual mentioned
these low-level functions:
Function Description
------------------------------------------------------------
fixterm restore tty to "in curses" state
gettmode establish current tty modes
mvcur low level cursor motion
putp utility function that uses tputs to send char-
acters via putchar.
resetterm set tty modes to "out of curses" state
resetty reset tty flags to stored value
saveterm save current modes as "in curses" state
savetty store current tty flags
setterm establish terminal with given type
setupterm establish terminal with given type
tparm instantiate a string expression with parameters
tputs apply padding information to a string
vidattr like vidputs, but outputs through putchar
vidputs output a string to put terminal in a specified
video attribute mode
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 apply padding to capability, calling
a function to put characters
Early terminfo programs obtained capability values from the TERMINAL
structure initialized by setupterm.
SVr3 extended terminfo by adding functions to retrieve capability val-
ues (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 which 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 han-
dling functions such as vidattr (which used more than the two parame-
ters supported by tgoto).
SVr3 introduced the functions for switching between terminal descrip-
tions, e.g., set_curterm. Some of that was incremental improvements to
the SVr2 library:
o The TERMINAL type definition was introduced in SVr3.01, for the
term structure provided in SVr2.
o The various global variables such as boolnames were mentioned in
the programming manual at this point, though the variables were
provided in SVr2.
SVr4 added the vid_attr and vid_puts functions.
There are other low-level functions declared in the curses header files
on Unix systems, but none were documented. The functions marked "obso-
lete" remained in use by the Unix vi(1) editor.
The functions marked as extensions were designed for ncurses(3x), and
are not found in SVr4 curses, 4.4BSD curses, or any other previous ver-
sion of curses.
X/Open notes that vidattr and vidputs may be macros.
The function setterm is not described by X/Open and must be considered
non-portable. All other functions are as described by X/Open.
setupterm copies the terminal name to the array ttytype. This is not
part of X/Open Curses, but is assumed by some applications.
Other implementions may not declare the capability name arrays. Some
provide them without declaring them. X/Open does not specify them.
Extended terminal capability names, e.g., as defined by tic -x, are not
stored in the arrays described here.
Older versions of ncurses assumed that the file descriptor passed to
setupterm from initscr or newterm uses buffered I/O, and would write to
the corresponding stream. In addition to the limitation that the ter-
minal was left in block-buffered mode on exit (like System V curses),
it was problematic because ncurses did not allow a reliable way to
cleanup on receiving SIGTSTP.
The current version (ncurses6) uses output buffers managed directly by
ncurses. Some of the low-level functions described in this manual page
write to the standard output. They are not signal-safe. The high-lev-
el functions in ncurses use alternate versions of these functions using
the more reliable buffering scheme.
The X/Open Curses prototypes are based on the SVr4 curses header decla-
rations, which were defined at the same time the C language was first
standardized in the late 1980s.
o X/Open Curses uses const less effectively than a later design
might, in some cases applying it needlessly to values are already
constant, and in most cases overlooking parameters which normally
would use const. Using constant parameters for functions which do
not use const may prevent the program from compiling. On the other
hand, writable strings are an obsolescent feature.
As an extension, this implementation can be configured to change
the function prototypes to use the const keyword. The ncurses ABI
6 enables this feature by default.
o X/Open Curses prototypes tparm with a fixed number of parameters,
rather than a variable argument list.
This implementation uses a variable argument list, but can be con-
figured to use the fixed-parameter list. Portable applications
should provide 9 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 only
available as a build-time configuration option. If not specially
configured, tparm is the same as tiparm.
Both forms of tparm have drawbacks:
o Most of the calls to tparm use 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 as a pointer. That ap-
proach dates back to the mid-1980s, before C was standardized.
Since then, there is a standard (and pointers are not required to
fit in a long).
o Providing the right number of parameters for a variadic function
such as tiparm can be a problem, in particular for string parame-
ters. However, only a few terminfo capabilities use string parame-
ters (e.g., the ones used for programmable function keys).
The ncurses library checks usage of these capabilities, and returns
an error if the capability mishandles string parameters. But it
cannot check if a calling program provides strings in the right
places for the tparm calls.
The tput(1) program checks its use of these capabilities with a ta-
ble, so that it calls tparm correctly.
If configured to use the terminal-driver, e.g., for the MinGW port,
o setupterm interprets a missing/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 gn
(generic_type) terminfo capability, while the latter does not. A
generic terminal is unsuitable for full-screen applications.
o setupterm allows explicit use of the the windows console driver by
checking if $TERM is set to "#win32con" or an abbreviation of that
string.
In System V Release 4, set_curterm has an int return type and returns
OK or ERR. We have chosen to implement the X/Open Curses semantics.
In System V Release 4, the third argument of tputs has the type int
(*putc)(char).
At least one implementation of X/Open Curses (Solaris) returns a value
other than OK/ERR from tputs. That returns the length of the string,
and does no error-checking.
X/Open notes that after calling mvcur, the curses state may not match
the actual terminal state, and that an application should touch and re-
fresh the window before resuming normal curses calls. Both ncurses and
System V Release 4 curses implement mvcur using the SCREEN data allo-
cated in either initscr or newterm. So though it is documented as a
terminfo function, mvcur is really a curses function which is not well
specified.
X/Open states that the old location must be given for mvcur. This im-
plementation allows the caller to use -1's for the old ordinates. In
that case, the old location is unknown.
curses(3x), curs_initscr(3x), curs_kernel(3x), curs_memleaks(3x),
curs_termcap(3x), curs_variables(3x), term_variables(3x), putc(3), ter-
minfo(5)
ncurses 6.4 2023-06-17 curs_terminfo(3x)