These low-level routines must be called by programs that have to deal
directly with the terminfo database to handle certain terminal
capabilities, such as programming function keys. For all other
functionality, curses routines are more suitable and their use is
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
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 setupterm
· 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 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
· 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
· 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.
is the file descriptor used for all output.
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
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 stdout.
The setterm routine was replaced by setupterm. The call:
setupterm(term, 1, (int *)0)
provides the same functionality as setterm(term). The setterm
routine is provided for BSD compatibility, and is not recommended for
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 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
terminal's capabilities in memory. If it is called for different
terminal types, setupterm allocates new storage for each set of
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,
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, except
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 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
· 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.
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.
The tputs routine applies padding information to the string str and
· 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
· affcnt is the number of lines affected, or 1 if not applicable.
· 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
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
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.,
· 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 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
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 effect
immediately (rather than at the next refresh).
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 section of
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
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, *boolfnamesconst char *numnames, *numcodes, *numfnamesconst char *strnames, *strcodes, *strfnames
Routines that return an integer return ERR upon failure and OK (SVr4
only specifies “an integer value other than ERR”) upon successful
completion, unless otherwise noted in the preceding routine
Routines that return pointers always return NULL on error.
X/Open defines no error conditions. In this implementation
returns an error if its terminal parameter is null.
putp calls tputs, returning the same error-codes.
returns an error if the associated call to setupterm returns
returns an error if it cannot allocate enough memory, or
create the initial windows (stdscr, curscr, newscr). Other
error conditions are documented above.
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.
SVr2 introduced the terminfo feature. Its programming manual
mentioned these low-level functions:
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
characters 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”):
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
values (like the termcap interface), and reusing tgoto and tputs:
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
Function Replaced by
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
descriptions, e.g., set_curterm. The various global variables such
as boolnames were mentioned in the programming manual at this point.
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 editor.
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
Legacy datasetupterm 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
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 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-level 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
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 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.
· 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
configured 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.
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
· setupterm allows explicit use of the the windows console driver
by checking if $TERM is set to “#win32con” or an abbreviation of
Other portability issues
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
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 ordinates.
In that case, the old location is unknown.
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