http://invisible-island.net/ncurses/man/


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 programs  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  capabilities  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 applications 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 li-
              brary would store a copy of the terminal description in the area
              referenced  by this pointer.  However, ncurses stores its termi-
              nal 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-address-
              ing.


CAPABILITY VALUES

       The tgetflag routine gets the boolean entry for id, or zero  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 returned string.  The area pa-
       rameter 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 al-
              so that the resulting buffer pointer is  not  NULL.   If  either
              check fails, the area parameter is ignored.

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

          o   The  return  value itself is an address in the terminal descrip-
              tion which is loaded into memory.

       Only the first two characters of the id parameter of tgetflag,  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 func-
           tion such as printf.

       o   While  tgoto is assumed to be used for the two-parameter cursor po-
           sitioning capability, termcap applications also use it for  single-
           parameter capabilities.

           Doing this shows a quirk in tgoto: most hardware terminals use cur-
           sor 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(3x) (a more capable formatter).

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


GLOBAL VARIABLES

       The variables PC, UP and BC are set by tgetent to the terminfo  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 terminal speed.


RETURN VALUE

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

       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 notation, not the older and
       not-quite-compatible termcap notation.  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 configured to  sup-
       port  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 capa-
       bilities 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 applications  assume  me  (terminfo
       sgr0)  does not reset the alternate character set.  This implementation
       checks for, and modifies the data shown to the termcap interface to ac-
       commodate termcap's limitation in this respect.


PORTABILITY

       The  XSI  Curses standard, Issue 4 describes these functions.  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 re-
       turned ever since SVr1.  In particular, 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  compati-
       bility  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 applica-
       tions.  However, termcap applications' use of those variables is poorly
       documented, e.g., not distinguishing between input and output.  In par-
       ticular,  some  applications  are reported to declare and/or modify os-
       peed.

       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.  Taking into account these is-
       sues:

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

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


SEE ALSO

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

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



                                                              curs_termcap(3x)