# curs_terminfo 3x 2025-02-15 ncurses 6.5 Library calls

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

## NAME

           del_curterm,  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 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  lower-level  functions  of the curses standard 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

           Call  setupterm  from  your  application  to  have  terminfo manage the
           terminal  device;  this  action  initializes   the   terminal-dependent
           variables  listed in term_variables(3x).  (A curses application calling
           initscr(3x) or newterm(3x) achieves the same result.)  Applications can
           use  the  terminal  capabilities either directly, by object definitions
           corresponding to capability names and codes (see term_variables(3x)) or
           by  calling  the  functions documented here.  setupterm initializes the
           terminfo variables lines and columns as described in use_env(3x).

           Pass  parameterized  string  capability   values   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(3x)  to restore the terminal modes before exiting.  (A
           curses application calling endwin(3x) achieves the same result.)

           Programs that use cursor addressing should emit certain capabilities at
           specific times.  Specifically, output

           o   enter_ca_mode upon startup, and

           o   exit_ca_mode before exiting.

           Programs that execute shell subprocesses should

           o   call  reset_shell_mode(3x) and output exit_ca_mode before the shell
               is called, and

           o   output enter_ca_mode and call reset_prog_mode(3x)  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  a  hard-copy  type  (lacks
                        destructive backspace), and  cannot  be  used  for  curses
                        applications.    The   library  determines  this  fact  by
                        checking the terminal type's 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 *) NULL, 1, (int *) NULL);

                   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  unavailable to
           applications.

           If setupterm is called repeatedly for the same terminal type, it reuses
           the  information.   It  maintains  only  one  copy  of  a  given type's
           capabilities in memory.   If  called  for  different  types,  setupterm
           allocates new storage for each set of terminal capabilities.

           set_curterm sets cur_term to nterm, making all of the terminfo Boolean,
           numeric, and string capabilities use the values from nterm.  It returns
           the old value of cur_term.

           del_curterm  frees  the memory pointed to by oterm, making it available
           for further use.  If oterm is the same as cur_term, references  to  any
           of  the  terminfo  Boolean, numeric, and string capabilities thereafter
           may refer to invalid memory locations until setupterm is called again.

           restartterm is similar to setupterm, but  is  intended  for  use  after
           restoring  program  memory  to  a  previous  state  (for  example, when
           reloading an application that has  been  suspended  from  one  terminal
           session and restored in another).  restartterm assumes that the display
           dimensions and the input and output options are the same as when memory
           was   saved,   but  the  terminal  type  and  line  speed  may  differ.
           Accordingly,  restartterm  saves   relevant   terminal   state,   calls
           setupterm, then restores that state.

### 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, 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 or tiparm.

           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.

           While putp is a lower-level function that  does  not  use  higher-level
           curses  state,  ncurses declares it in curses.h because System V did so
           (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  of  that
           name in the "Predefined 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

           NULL   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

           Functions that return integers return ERR  upon  failure  and  OK  upon
           success.

           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 ERR.

           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 originated in 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

           Except for setterm, X/Open Curses Issue 4  describes  these  functions.
           It specifies no error conditions for them.

           SVr4 describes a successful return value except where "otherwise noted"
           as "an integer value other than ERR".

### Header Files

           On legacy curses systems, include curses.h and term.h in that order  to
           make   visible  the  definitions  of  the  string  arrays  storing  the
           capability names and codes.

### Compatibility Macros

           ncurses implements a few macros for early System V curses compatibility
           (see section "HISTORY" below).  They include crmode, fixterm, gettmode,
           nocrmode, resetterm, saveterm, and setterm.

           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)
           and discouraging the latter for new programs.

### Legacy Data

           setupterm copies the terminal name to the array ttytype.  This behavior
           is not specified by X/Open Curses, but is assumed by some applications.

           Other implementations may not declare the capability name arrays.  Some
           provide  them  without  declaring them.  X/Open Curses 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 used buffered I/O, and wrote  to  the
           corresponding  stdio  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 clean up on receiving SIGTSTP.

           ncurses 6.x uses output  buffers  managed  directly  by  ncurses.   The
           lower-level  functions described here that write to the terminal device
           do so via the standard output stream; they thus  are  not  signal-safe.
           The  higher-level  functions  in  ncurses  employ alternate versions of
           these functions using a 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,  sometimes applying it needlessly to values that are already
               constant, and in most cases overlooking  parameters  that  normally
               would  benefit  from  const.  Passing const-qualified parameters to
               functions that do not declare them const may  prevent  the  program
               from  compiling.   On  the  other  hand,  "writable strings" are an
               obsolescent C language feature.

               As an extension, ncurses 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.

               ncurses 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
               available  only  as  a  build-time  configuration  option.   If not
               specially configured, tparm is the same as tiparm.

           Both forms of tparm have drawbacks.

           o   Most calls to tparm require 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  memory  as  a  pointer.
               That  approach  dates  to the mid-1980s, before C was standardized.
               Since ANSI C (1989), C language standards do not require a  pointer
               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
               ERR if the capability mishandles string parameters.  But it  cannot
               check if a calling program provides strings in the right places for
               the tparm calls.

               ncurses's tput(1) checks its  use  of  these  capabilities  with  a
               table, so that it calls tparm correctly.

       Special TERM treatment
           If  ncurses is 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 Microsoft Windows console
               driver by checking whether the TERM environment  variable  has  the
               value "#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 (*)(char)".

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

## 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 6.5                       2025-02-15                 curs_terminfo(3x)