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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | HISTORY | PORTABILITY | SEE ALSO | COLOPHON |
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curs_terminfo(3X) curs_terminfo(3X)
del_curterm, mvcur, putp, restartterm, set_curterm, setupterm,
tigetflag, tigetnum, tigetstr, tiparm, 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, ...);
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, ...);
These low-level routines must be called by programs that have to
deal directly with the terminfo database to handle certain termi‐
nal capabilities, 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:
• capability names use the POSIX portable character set
• capability string values have no associated encoding; they
are strings of 8-bit characters.
Initialization
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 termin‐
fo(5)].
Applications can use the terminal capabilities either directly
(via header definitions), or by special functions. The header
files curses.h and term.h should be included (in this order) to
get the definitions for these strings, numbers, and flags.
The terminfo variables lines and columns are initialized by se‐
tupterm as follows:
• If use_env(FALSE) has been called, values for lines and
columns specified in terminfo are used.
• Otherwise, if the environment variables LINES and COLUMNS ex‐
ist, their values are used. If these environment variables
do not exist and the program is running in a window, the cur‐
rent 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 instanti‐
ate 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
• output enter_ca_mode upon startup and
• output exit_ca_mode before exiting.
Programs which execute shell subprocesses should
• call reset_shell_mode and output exit_ca_mode before the
shell is called and
• output enter_ca_mode and call reset_prog_mode after returning
from the shell.
The setupterm routine reads in the terminfo database, initializ‐
ing the terminfo structures, but does not set up the output vir‐
tualization 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 all output.
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 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) capability.
-1 means that the terminfo database could not be found.
If errret is null, setupterm prints an error message upon
finding 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 std‐
out.
The Terminal State
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 informa‐
tion, 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 giv‐
en terminal's capabilities in memory. If it is called for dif‐
ferent terminal types, setupterm allocates new storage for each
set of terminal capabilities.
The set_curterm routine sets cur_term to nterm, and makes all of
the terminfo boolean, numeric, and string variables use the val‐
ues 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, references to any of the terminfo boolean, numeric, and
string variables thereafter may refer to invalid memory locations
until another setupterm has been called.
The restartterm routine is similar to setupterm and initscr, ex‐
cept that it is called after restoring memory to a previous state
(for example, when reloading a game saved as a core image dump).
restartterm assumes that the windows and the input and output op‐
tions 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.
Formatting Output
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 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 which uses <stdarg.h> rather than
a fixed-parameter list. Its numeric parameters are integers
(int) rather than longs.
Output Functions
The tputs routine applies padding information (i.e., by inter‐
preting marker embedded in the terminfo capability such as “$<5>”
as 5 milliseconds) to the string str and outputs it:
• 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 in‐
terface, which happens to share this function name with the
terminfo interface.
• affcnt is the number of lines affected, or 1 if not applica‐
ble.
• 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 always 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 at‐
tributes 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 vid‐
puts, respectively. They use a set of arguments for representing
the video attributes plus color, i.e.,
• attrs of type attr_t for the attributes and
• pair of type short for the color-pair number.
The vid_attr and vid_puts routines are designed to use the at‐
tribute 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 extension, 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 ef‐
fect immediately (rather than at the next refresh).
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).
Terminal Capability Functions
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 sec‐
tion 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.
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 of the predefined terminfo variables:
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 al‐
located by setupterm:
• 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.
• to improve performance, ncurses 6.3 caches the result of ana‐
lyzing terminfo strings for their parameter types. That is
stored as a binary tree referenced from the TERMINAL struc‐
ture.
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 suc‐
cessful completion, unless otherwise noted in the preceding rou‐
tine 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 re‐
turns an error.
setupterm
returns an error if it cannot allocate enough memory, or
create the initial windows (stdscr, curscr, newscr).
Other error conditions are documented above.
tputs
returns an error if the string parameter is null. It
does not detect I/O errors: X/Open states that tputs ig‐
nores the return value of the output function putc.
Compatibility macros
This implementation provides a few macros for compatibility with
systems before SVr4 (see HISTORY). Those include crmode, fix‐
term, 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 rec‐
ommended for new programs. This implementation provides each of
those symbols 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 TER‐
MINAL structure initialized by setupterm.
SVr3 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 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 handling functions such as vidattr (which used more
than the two parameters supported by tgoto).
SVr3 introduced the functions for switching between terminal de‐
scriptions, e.g., set_curterm. Some of that was incremental im‐
provements to the SVr2 library:
• The TERMINAL type definition was introduced in SVr3.01, for
the term structure provided in SVr2.
• 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 “obsolete” remained in use by the Unix vi(1) editor.
Legacy functions
X/Open notes that vidattr and vidputs may be macros.
The function setterm is not described by X/Open and must be con‐
sidered non-portable. All other functions are as described by
X/Open.
Legacy data
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 speci‐
fy them.
Extended terminal capability names, e.g., 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 uses buffered I/O, and would
write to the corresponding 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 al‐
low a reliable way to cleanup on receiving SIGTSTP.
The current version (ncurses6) uses output buffers managed di‐
rectly by ncurses. Some of the low-level functions described in
this manual page write to the standard output. They are not sig‐
nal-safe. The high-level functions in ncurses use alternate ver‐
sions of these functions using the 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, in some cases applying it needlessly to values are al‐
ready 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.
• X/Open Curses prototypes tparm with a fixed number of parame‐
ters, rather than a variable argument list.
This implementation uses a variable argument list, but can be
configured to use the fixed-parameter list. Portable appli‐
cations 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.
Special TERM treatment
If configured to use the terminal-driver, e.g., for the MinGW
port,
• setupterm interprets a missing/empty TERM variable as the
special value “unknown”.
• setupterm allows explicit use of the the windows console dri‐
ver by checking if $TERM is set to “#win32con” or an abbrevi‐
ation of that string.
Other portability issues
In System V Release 4, set_curterm has an int return type and re‐
turns 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 refresh the window before resuming normal curses calls.
Both ncurses and System V Release 4 curses implement mvcur using
the SCREEN data allocated 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 implementation allows the caller to use -1's for the old or‐
dinates. 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), terminfo(5)
This page is part of the ncurses (new curses) project. Informa‐
tion 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
bug-ncurses-request@gnu.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨https://github.com/mirror/ncurses.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2023-03-12.) 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
curs_terminfo(3X)
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HTML rendering created 2024-06-26 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. |
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