curs_terminfo(3x) — Linux manual page


curs_terminfo(3X)                                      curs_terminfo(3X)

NAME         top

       del_curterm, mvcur, putp, restartterm, set_curterm, setupterm,
       tigetflag, tigetnum, tigetstr, tiparm, tparm, tputs, vid_attr,
       vid_puts, vidattr, vidputs - curses interfaces to terminfo

SYNOPSIS         top

       #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, ...);

DESCRIPTION         top

       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 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.

       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

       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 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
           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

       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,
       initializing the terminfo structures, but does not set up the
       output virtualization structures used by curses.  These are its

          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 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

   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 terminal capabilities.

       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.

   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

       •   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
       interpreting 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
           interface, which happens to share this function name with the
           terminfo interface.

       •   affcnt is the number of lines affected, or 1 if not

       •   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 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.,

       •   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).

       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
       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.

   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


       the memory will be freed.

       The formatting functions tparm and tiparm extend the storage
       allocated 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
           analyzing terminfo strings for their parameter types.  That
           is stored as a binary tree referenced from the TERMINAL

       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.

RETURN VALUE         top

       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 descriptions.

       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 an error.

               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.

   Compatibility macros
       This implementation provides a few macros for compatibility with
       systems 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
       recommended for new programs.  This implementation provides each
       of those symbols as macros for BSD compatibility,

HISTORY         top

       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
                   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”):
       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
       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
       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
       descriptions, e.g., set_curterm.  Some of that was incremental
       improvements 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.

PORTABILITY         top

   Legacy functions
       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 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
       specify 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
       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

   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
           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

       •   setupterm interprets a missing/empty TERM variable as the
           special value “unknown”.

       •   setupterm allows explicit use of the the windows console
           driver by checking if $TERM is set to “#win32con” or an
           abbreviation of that string.

   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

       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.

SEE ALSO         top

       curses(3X), curs_initscr(3X), curs_kernel(3X), curs_memleaks(3X),
       curs_termcap(3X), curs_variables(3X), term_variables(3X),
       putc(3), terminfo(5)

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