# curs_termcap 3x

    curs_termcap(3x)                                       curs_termcap(3x)

## NAME

           PC, UP, BC, ospeed, tgetent, tgetflag, tgetnum, tgetstr,
           tgoto, tputs - direct curses interface to the terminfo
           capability database

## SYNOPSIS

           #include <curses.h>
           #include <term.h>

           extern char PC;
           extern char * UP;
           extern char * BC;
           extern short ospeed;

           int tgetent(char *bp, const char *name);
           int tgetflag(char *id);
           int tgetnum(char *id);
           char *tgetstr(char *id, char **area);
           char *tgoto(const char *cap, int col, int row);
           int tputs(const char *str, int affcnt, int (*putc)(int));

## DESCRIPTION

           These  routines  are included as a conversion aid for pro-
           grams that use the termcap library.  Their parameters  are
           the  same and the routines are emulated using the terminfo
           database.  Thus, they can only be used to query the  capa-
           bilities  of  entries  for which a terminfo entry has been
           compiled.

### INITIALIZATION

           The tgetent routine loads the entry for name.  It returns:

              1  on success,

              0  if there is no such entry (or that it is  a  generic
                 type,  having  too little information for curses ap-
                 plications to run), and

              -1 if the terminfo database could not be found.

           This differs from the termcap library in two ways:

              o   The emulation ignores the buffer pointer  bp.   The
                  termcap  library would store a copy of the terminal
                  description in the area referenced by this pointer.
                  However,  ncurses  stores its terminal descriptions
                  in compiled binary form,  which  is  not  the  same
                  thing.

              o   There is a difference in return codes.  The termcap
                  library does not check if the terminal  description
                  is  marked  with  the generic capability, or if the
                  terminal description has cursor-addressing.

### CAPABILITY VALUES

           The tgetflag routine gets the boolean entry for id, or ze-
           ro if it is not available.

           The  tgetnum  routine gets the numeric entry for id, or -1
           if it is not available.

           The tgetstr routine returns the string entry  for  id,  or
           zero  if it is not available.  Use tputs to output the re-
           turned string.  The area parameter is used as follows:

              o   It is assumed to be the address of a pointer  to  a
                  buffer managed by the calling application.

              o   However,  ncurses checks to ensure that area is not
                  NULL, and also that the resulting buffer pointer is
                  not  NULL.  If either check fails, the area parame-
                  ter is ignored.

              o   If the checks succeed, ncurses also copies the  re-
                  turn  value  to  the buffer pointed to by area, and
                  the area value will be updated to  point  past  the
                  null ending this value.

              o   The return value itself is an address in the termi-
                  nal description which is loaded into memory.

           Only the first two characters of the id parameter of tget-
           flag, tgetnum and tgetstr are compared in lookups.

### FORMATTING CAPABILITIES

           The  tgoto  routine  instantiates  the parameters into the
           given capability.  The output from this routine is  to  be
           passed to tputs.

           The  tputs  routine  is described on the curs_terminfo(3x)
           manual page.  It can retrieve capabilities by either term-
           cap or terminfo name.

### GLOBAL VARIABLES

           The variables PC, UP and BC are set by tgetent to the ter-
           minfo   entry's   data   for   pad_char,   cursor_up   and
           backspace_if_not_bs,  respectively.   UP  is  not  used by
           ncurses.  PC is used in the tdelay_output function.  BC is
           used  in  the tgoto emulation.  The variable ospeed is set
           by ncurses in a system-specific coding to reflect the ter-
           minal speed.

## RETURN VALUE

           Except where explicitly noted, routines that return an in-
           teger return ERR upon failure and OK (SVr4 only  specifies
           "an integer value other than ERR") upon successful comple-
           tion.

           Routines that return pointers return NULL on error.

## BUGS

           If you call tgetstr to fetch ca or any other parameterized
           string,  be aware that it will be returned in terminfo no-
           tation, not the older and not-quite-compatible termcap no-
           tation.   This  will not cause problems if all you do with
           it is call tgoto or tparm,  which  both  expand  terminfo-
           style  strings  as terminfo.  (The tgoto function, if con-
           figured to support termcap, will check if  the  string  is
           indeed  terminfo-style  by  looking for "%p" parameters or
           "$<..>" delays, and invoke a termcap-style parser  if  the
           string does not appear to be terminfo).

           Because  terminfo  conventions for representing padding in
           string capabilities differ  from  termcap's,  tputs("50");
           will  put  out a literal "50" rather than busy-waiting for
           50 milliseconds.  Cope with it.

           Note that termcap has nothing analogous to terminfo's  sgr
           string.   One consequence of this is that termcap applica-
           tions assume me (terminfo sgr0) does not reset the  alter-
           nate  character  set.  This implementation checks for, and
           modifies the data shown to the termcap interface to accom-
           modate termcap's limitation in this respect.

## PORTABILITY

           The  XSI  Curses  standard,  Issue 4 describes these func-
           tions.  However, they are marked TO BE WITHDRAWN  and  may
           be removed in future versions.

           Neither  the  XSI  Curses  standard nor the SVr4 man pages
           documented the return values of tgetent correctly,  though
           all  three were in fact returned ever since SVr1.  In par-
           ticular, an omission in the XSI Curses  documentation  has
           been  misinterpreted  to  mean  that tgetent returns OK or
           ERR.  Because the purpose of these functions is to provide
           compatibility  with  the termcap library, that is a defect
           in XCurses, Issue 4, Version 2 rather than in ncurses.

           External variables are provided  for  support  of  certain
           termcap  applications.  However, termcap applications' use
           of those variables is poorly documented, e.g., not distin-
           guishing  between  input  and output.  In particular, some
           applications are reported to declare and/or modify ospeed.

           The comment that only the first two characters of  the  id
           parameter  are  used  escapes many application developers.
           The original  BSD  4.2  termcap  library  (and  historical
           relics thereof) did not require a trailing null NUL on the
           parameter name passed to tgetstr,  tgetnum  and  tgetflag.
           Some  applications  assume that the termcap interface does
           not require the trailing NUL for the parameter name.  Tak-
           ing into account these issues:

           o   As  a special case, tgetflag matched against a single-
               character identifier provided that was at the  end  of
               the  terminal  description.   You should not rely upon
               this behavior in portable programs.  This  implementa-
               tion  disallows matches against single-character capa-
               bility names.

           o   This implementation disallows matches by  the  termcap
               interface  against extended capability names which are
               longer than two characters.

## SEE ALSO

           curses(3x), terminfo(5), term_variables(3x), putc(3).

           http://invisible-island.net/ncurses/tctest.html

                                                           curs_termcap(3x)