# curs_terminfo 3x 2024-01-13 ncurses 6.4 Library calls

    curs_terminfo(3x)                Library calls               curs_terminfo(3x)

## NAME

           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

## SYNOPSIS

           #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 *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);

## DESCRIPTION

           These low-level functions 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.

           o   Capability names and codes use the POSIX portable character set.

           o   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 term_variables(3x).

           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 that order) to get the
           definitions 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
           sent  to the terminal device with tputs or putp.  Call reset_shell_mode
           to restore the terminal modes before exiting; see curs_kernel(3x).

           Programs that use cursor addressing should

           o   output enter_ca_mode upon startup and

           o   output exit_ca_mode before exiting.

           Programs that 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.

           setupterm reads in the terminfo  database,  initializing  the  terminfo
           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 hardcopy, and  cannot  be  used
                        for curses applications.

                        setupterm  determines  if  the entry is a hardcopy type by
                        checking the 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 *)0, 1, (int *)0);

                   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 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.

           set_curterm 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.

           del_curterm 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.

           restartterm 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  terminal  state  bits, calls
           setupterm, and then restores the bits.

### Formatting Output

           tparm 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:

           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
               capabilities 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 ints 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) passed as char pointers rather than numbers.

           o   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  information,  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), it is capped at that value.

           tputs interprets time-delay information in the string str  and  outputs
           it, executing the delays:

           o   The  str parameter must be a terminfo string variable or the return
               value of tparm, tiparm, tgetstr, or tgoto.

               The tgetstr and tgoto functions are part of the termcap  interface,
               which happens to share these function names with the terminfo API.

           o   affcnt is the number of lines affected, or 1 if not applicable.

           o   putc is a putchar-like function to which the characters are passed,
               one at a time.

               If tputs processes  a  time-delay,  it  uses  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,

           o   attrs, of type attr_t, for the attributes and

           o   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.

           mvcur 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 that do not use high-level
           curses  state,  ncurses  declares them in curses.h because System V did
           this (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  entitled
           cap-code code 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

           0      if it is canceled or absent from the terminal description.

### Terminal Capability Names

           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[]

### 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.

           o   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).

           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.

## RETURN VALUE

           X/Open Curses defines no failure conditions.  In ncurses,

           del_curtem
                fails if its terminal parameter is null.

           putp calls tputs, returning the same error codes.

           restartterm
                fails if the associated call to setupterm returns an error.

           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.

## NOTES

           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.

## EXTENSIONS

           The functions marked as extensions were designed for 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.

## PORTABILITY

           setterm is not described by X/Open and must be considered non-portable.
           All other functions are as described by X/Open.

### Compatibility Macros

           This implementation  provides  a  few  macros  for  compatibility  with
           systems  before  SVr4  (see  section  "HISTORY"  below).   They include
           Bcrmode, Bfixterm, Bgettmode,  Bnocrmode,  Bresetterm,  Bsaveterm,  and
           Bsetterm.

           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),  discouraging  the
           latter  for  new programs.  ncurses implements each of these symbols as
           macros for BSD curses compatibility.

### 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, 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 employ alternate versions 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.

           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
               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  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
               approach  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
               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
               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
               table, so that it calls tparm correctly.

       Special TERM treatment
           If configured to use the terminal driver, as with 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
               generic_type  (gn)  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.

### 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 (*putc)(char)".

           At  least one implementation of X/Open Curses (Solaris) returns a value
           other than OK or ERR from tputs.  It instead returns the length of  the
           string, and does no error checking.

           X/Open  Curses 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 SVr4 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 that is not well specified.

           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  SVr4  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 that is not well specified.

           X/Open  Curses  states that the old location must be given for mvcur to
           accommodate terminals that lack absolute cursor  positioning.   ncurses
           allows the caller to use -1 for either or both old coordinates.  The -1
           tells ncurses that the old location is unknown, and that  it  must  use
           only  absolute  motion,  as  with  the cursor_address (cup) capability,
           rather than the least  costly  combination  of  absolute  and  relative
           motion.

## HISTORY

           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.

           o   The TERMINAL type definition was introduced  in  SVr3.01,  for  the
               term structure provided in SVr2.

           o   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.

## SEE ALSO

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

    ncurses 6.4                       2024-01-13                 curs_terminfo(3x)