.\"***************************************************************************
-.\" Copyright (c) 1998-2016,2017 Free Software Foundation, Inc. *
+.\" Copyright 2018-2019,2020 Thomas E. Dickey *
+.\" Copyright 1998-2017,2018 Free Software Foundation, Inc. *
.\" *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" copy of this software and associated documentation files (the *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_termcap.3x,v 1.33 2017/01/07 19:25:15 tom Exp $
+.\" $Id: curs_termcap.3x,v 1.44 2020/05/17 01:20:13 tom Exp $
.TH curs_termcap 3X ""
+.ie \n(.g .ds `` \(lq
+.el .ds `` ``
+.ie \n(.g .ds '' \(rq
+.el .ds '' ''
.de bP
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
..
.na
.hy 0
.sp
\fBint tgetent(char *bp, const char *name);\fR
.br
-\fBint tgetflag(char *id);\fR
+\fBint tgetflag(const char *id);\fR
.br
-\fBint tgetnum(char *id);\fR
+\fBint tgetnum(const char *id);\fR
.br
-\fBchar *tgetstr(char *id, char **area);\fR
+\fBchar *tgetstr(const char *id, char **area);\fR
.br
\fBchar *tgoto(const char *cap, int col, int row);\fR
.br
.br
.SH DESCRIPTION
These routines are included as a conversion aid for programs that use
-the \fItermcap\fR library. Their parameters are the same and the
-routines are emulated using the \fIterminfo\fR database. Thus, they
+the \fItermcap\fR library.
+Their parameters are the same and the
+routines are emulated using the \fIterminfo\fR database.
+Thus, they
can only be used to query the capabilities of entries for which a
terminfo entry has been compiled.
.SS INITIALIZATION
.bP
Normally the ncurses library is compiled with terminfo support.
In that case, \fBtgoto\fP uses \fBtparm\fP(3X) (a more capable formatter).
+.IP
+However, \fBtparm\fP is not a \fItermcap\fP feature,
+and portable \fItermcap\fP applications should not rely upon its availability.
.PP
The \fBtputs\fR routine is described on the \fBcurs_terminfo\fR(3X) manual
-page. It can retrieve capabilities by either termcap or terminfo name.
+page.
+It can retrieve capabilities by either termcap or terminfo name.
.SS GLOBAL VARIABLES
.PP
The variables
.SH BUGS
If you call \fBtgetstr\fR to fetch \fBca\fR 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
+not-quite-compatible termcap notation.
+This will not cause problems if all
you do with it is call \fBtgoto\fR or \fBtparm\fR, which both expand
terminfo-style strings as terminfo.
(The \fBtgoto\fR function, if configured to support termcap, will check
appear to be terminfo).
.PP
Because terminfo conventions for representing padding in string capabilities
-differ from termcap's, \fBtputs("50");\fR will put out a literal "50" rather
-than busy-waiting for 50 milliseconds. Cope with it.
+differ from termcap's, \fBtputs("50");\fR will put out a literal \*(``50\*('' rather
+than busy-waiting for 50 milliseconds.
+Cope with it.
.PP
Note that termcap has nothing analogous to terminfo's \fBsgr\fR string.
One consequence of this is that termcap applications assume \fRme\fR
This implementation checks for, and modifies the data shown to the
termcap interface to accommodate termcap's limitation in this respect.
.SH PORTABILITY
-The XSI Curses standard, Issue 4 describes these functions. However, they
+.SS Standards
+These functions are provided for supporting legacy applications,
+and should not be used in new programs:
+.bP
+The XSI Curses standard, Issue 4 describes these functions.
+However, they
are marked TO BE WITHDRAWN and may be removed in future versions.
+.bP
+X/Open Curses, Issue 5 (December 2007) marked the termcap interface
+(along with \fBvwprintw\fP and \fBvwscanw\fP) as withdrawn.
.PP
Neither the XSI Curses standard nor the SVr4 man pages documented the return
values of \fBtgetent\fR correctly, though all three were in fact returned ever
Because the purpose of these functions is to provide compatibility with
the \fItermcap\fR library, that is a defect in XCurses, Issue 4, Version 2
rather than in ncurses.
+.SS Compatibility with BSD Termcap
.PP
External variables are provided for support of certain termcap applications.
However, termcap applications' use of those variables is poorly documented,
.bP
This implementation disallows matches by the termcap interface against
extended capability names which are longer than two characters.
+.PP
+The BSD termcap function \fBtgetent\fP returns the text of a termcap
+entry in the buffer passed as an argument.
+This library (like other terminfo implementations) does not store
+terminal descriptions as text.
+It sets the buffer contents to a null-terminated string.
+.SS Other Compatibility
+This library includes a termcap.h header,
+for compatibility with other implementations.
+But the header is rarely used because the other implementations
+are not strictly compatible.
+.PP
+The original BSD termcap (through 4.3BSD) had no header file which
+gave function prototypes, because that was a feature of ANSI C.
+BSD termcap was written several years before C was standardized.
+However, there were two different termcap.h header files in the BSD
+sources:
+.bP
+One was used internally by the \fIjove\fP editor in 2BSD through 4.4BSD.
+It defined global symbols for the termcap variables which it used.
+.bP
+The other appeared in 4.4BSD Lite Release 2 (mid-1993)
+as part of \fIlibedit\fP (also known as the \fIeditline\fP library).
+The CSRG source history shows that this was added in mid-1992.
+The \fIlibedit\fP header file was used internally,
+as a convenience for compiling the \fIeditline\fP library.
+It declared function prototypes, but no global variables.
+.PP
+The header file from \fIlibedit\fP was added to NetBSD's termcap
+library in mid-1994.
+.PP
+Meanwhile, GNU termcap was under development, starting in 1990.
+The first release (termcap 1.0) in 1991 included a termcap.h header.
+The second release (termcap 1.1) in September 1992 modified the
+header to use \fBconst\fP for the function prototypes in the header
+where one would expect the parameters to be read-only.
+This was a difference versus the original BSD termcap.
+The prototype for \fBtputs\fP also differed,
+but in that instance, it was \fIlibedit\fP which differed from BSD termcap.
+.PP
+A copy of GNU termcap 1.3 was bundled with \fIbash\fP in mid-1993,
+to support the \fIreadline\fP library.
+.PP
+A termcap.h file was provided in ncurses 1.8.1 (November 1993).
+That reflected influence by \fIemacs\fP (rather than \fIjove\fP)
+and GNU termcap:
+.bP
+it provided declarations for a few global symbols used by \fIemacs\fP
+.bP
+it provided function prototypes (using \fBconst\fP).
+.bP
+a prototype for \fBtparam\fP (a GNU termcap feature) was provided.
+.PP
+Later (in mid-1996) the \fBtparam\fP function was removed from ncurses.
+As a result, there are differences between any of the four implementations,
+which must be taken into account by programs which can work with all
+termcap library interfaces.
.SH SEE ALSO
\fBcurses\fR(3X),
\fBterminfo\fR(\*n),
\fBterm_variables\fR(3X),
\fBputc\fR(3).
.sp
-http://invisible-island.net/ncurses/tctest.html
+https://invisible-island.net/ncurses/tctest.html
projects / ncurses.git / blobdiff