curs_termcap

Section: Miscellaneous Library Functions (3X)
Updated:
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NAME

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 unsigned 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.

The tgetent routine loads the entry for name. It returns 1 on success, 0 if there is no such entry, and -1 if the terminfo database could not be found. The emulation ignores the buffer pointer bp.

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 return value will also be copied to the buffer pointed to by area, and the area value will be updated to point past the null ending this value.

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

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 termcap or terminfo name.

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 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 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 accommodate 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 returned 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 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 distinguishing between input and output. In particular, some applications are reported to declare and/or modify ospeed.