# 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 expands the given capability using the
           parameters.

           o   Because the capability may  have  padding  characters,
               the  output  of tgoto should be passed to tputs rather
               than some other output function such as printf.

           o   While tgoto is assumed to be used for the  two-parame-
               ter  cursor  positioning  capability, termcap applica-
               tions also use it for single-parameter capabilities.

               Doing this shows a quirk in tgoto: most hardware  ter-
               minals  use  cursor addressing with row first, but the
               original developers of the termcap interface chose  to
               put  the  column  parameter first.  The tgoto function
               swaps the order of parameters.  It does this also  for
               calls  requiring  only  a  single  parameter.  In that
               case, the first parameter is merely a placeholder.

           o   Normally the ncurses library is compiled with terminfo
               support.  In that case, tgoto uses tparm (a more capa-
               ble formatter).

           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)