<!--
****************************************************************************
- * Copyright 2018-2022,2022 Thomas E. Dickey *
+ * Copyright 2018-2022,2023 Thomas E. Dickey *
* Copyright 1998-2017,2018 Free Software Foundation, Inc. *
* *
* Permission is hereby granted, free of charge, to any person obtaining a *
* sale, use or other dealings in this Software without prior written *
* authorization. *
****************************************************************************
- * @Id: curs_termcap.3x,v 1.56 2022/02/12 20:05:11 tom Exp @
+ * @Id: curs_termcap.3x,v 1.57 2023/04/08 21:43:01 tom Exp @
-->
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<HTML>
first parameter is merely a placeholder.
<STRONG>o</STRONG> Normally the ncurses library is compiled with terminfo support. In
- that case, <STRONG>tgoto</STRONG> uses <STRONG><A HREF="curs_terminfo.3x.html">tparm(3x)</A></STRONG> (a more capable formatter).
+ that case, <STRONG>tgoto</STRONG> uses an internal version of <STRONG><A HREF="curs_terminfo.3x.html">tparm(3x)</A></STRONG> (a more ca-
+ pable formatter).
- However, <STRONG>tparm</STRONG> is not a <EM>termcap</EM> feature, and portable <EM>termcap</EM> ap-
+ With terminfo support, <STRONG>tgoto</STRONG> is able to use some of the terminfo
+ features, but not all. In particular, it allows only numeric pa-
+ rameters; <STRONG>tparm</STRONG> supports string parameters.
+
+ However, <STRONG>tparm</STRONG> is not a <EM>termcap</EM> feature, and portable <EM>termcap</EM> ap-
plications should not rely upon its availability.
- The <STRONG>tputs</STRONG> routine is described on the <STRONG><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG> manual page.
+ The <STRONG>tputs</STRONG> routine is described on the <STRONG><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG> manual page.
It can retrieve capabilities by either termcap or terminfo name.
</PRE><H3><a name="h3-Global-Variables">Global Variables</a></H3><PRE>
- The variables <STRONG>PC</STRONG>, <STRONG>UP</STRONG> and <STRONG>BC</STRONG> are set by <STRONG>tgetent</STRONG> to the terminfo entry's
+ The variables <STRONG>PC</STRONG>, <STRONG>UP</STRONG> and <STRONG>BC</STRONG> are set by <STRONG>tgetent</STRONG> to the terminfo entry's
data for <STRONG>pad_char</STRONG>, <STRONG>cursor_up</STRONG> and <STRONG>backspace_if_not_bs</STRONG>, respectively. <STRONG>UP</STRONG>
- is not used by ncurses. <STRONG>PC</STRONG> is used in the <STRONG>tdelay_output</STRONG> function. <STRONG>BC</STRONG>
- is used in the <STRONG>tgoto</STRONG> emulation. The variable <STRONG>ospeed</STRONG> is set by ncurses
+ is not used by ncurses. <STRONG>PC</STRONG> is used in the <STRONG>tdelay_output</STRONG> function. <STRONG>BC</STRONG>
+ is used in the <STRONG>tgoto</STRONG> emulation. The variable <STRONG>ospeed</STRONG> is set by ncurses
in a system-specific coding to reflect the terminal speed.
</PRE><H3><a name="h3-Releasing-Memory">Releasing Memory</a></H3><PRE>
- The termcap functions provide no means for freeing memory, because
- legacy termcap implementations used only the buffer areas provided by
- the caller via <STRONG>tgetent</STRONG> and <STRONG>tgetstr</STRONG>. Those buffers are unused in ter-
+ The termcap functions provide no means for freeing memory, because
+ legacy termcap implementations used only the buffer areas provided by
+ the caller via <STRONG>tgetent</STRONG> and <STRONG>tgetstr</STRONG>. Those buffers are unused in ter-
minfo.
On the other hand, terminfo allocates memory. It uses <STRONG>setupterm</STRONG> to re-
<STRONG>del_curterm(cur_term);</STRONG>
- to free this memory, but there is an additional complication with
- ncurses. It uses a fixed-size <EM>pool</EM> of storage locations, one per set-
- ting of the <STRONG>TERM</STRONG> variable when <STRONG>tgetent</STRONG> is called. The <STRONG>screen(1)</STRONG> pro-
+ to free this memory, but there is an additional complication with
+ ncurses. It uses a fixed-size <EM>pool</EM> of storage locations, one per set-
+ ting of the <STRONG>TERM</STRONG> variable when <STRONG>tgetent</STRONG> is called. The <STRONG>screen(1)</STRONG> pro-
gram relies upon this arrangement, to improve its performance.
- An application which uses only the low-level termcap functions could
+ An application which uses only the low-level termcap functions could
free the memory using <STRONG>del_curterm</STRONG>, because the pool is freed using oth-
er functions (see <STRONG><A HREF="curs_memleaks.3x.html">curs_memleaks(3x)</A></STRONG>).
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
- Except where explicitly noted, routines that return an integer return
- <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> (SVr4 only specifies "an integer value other
+ Except where explicitly noted, routines that return an integer return
+ <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> (SVr4 only specifies "an integer value other
than <STRONG>ERR</STRONG>") upon successful completion.
Routines that return pointers return <STRONG>NULL</STRONG> on error.
+ A few special cases apply:
+
+ <STRONG>o</STRONG> If the terminal database has not been initialized, these return an
+ error.
+
+ <STRONG>o</STRONG> The calls with a string parameter (<STRONG>tgoto</STRONG>, <STRONG>tputs</STRONG>) check if the
+ string is null, or cancelled. Those return an error.
+
+ <STRONG>o</STRONG> A call to <STRONG>tgoto</STRONG> using a capability with string parameters is an er-
+ ror.
+
+ <STRONG>o</STRONG> A call to <STRONG>tgoto</STRONG> using a capability with no parameters, or more than
+ two is an error.
+
</PRE><H2><a name="h2-BUGS">BUGS</a></H2><PRE>
- If you call <STRONG>tgetstr</STRONG> to fetch <STRONG>ca</STRONG> or any other parameterized string, be
- aware that it will be returned in terminfo notation, not the older and
+ If you call <STRONG>tgetstr</STRONG> to fetch <STRONG>ca</STRONG> 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 <STRONG>tgoto</STRONG> or <STRONG>tparm</STRONG>, which both expand terminfo-
- style strings as terminfo. (The <STRONG>tgoto</STRONG> function, if configured to sup-
- port termcap, will check if the string is indeed terminfo-style by
- looking for "%p" parameters or "$<..>" delays, and invoke a termcap-
+ all you do with it is call <STRONG>tgoto</STRONG> or <STRONG>tparm</STRONG>, which both expand terminfo-
+ style strings as terminfo. (The <STRONG>tgoto</STRONG> function, if configured to sup-
+ port termcap, will check if the string is indeed terminfo-style by
+ looking for "%p" parameters or "$<..>" 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-
+ Because terminfo conventions for representing padding in string capa-
bilities differ from termcap's, users can be surprised:
<STRONG>o</STRONG> <STRONG>tputs("50")</STRONG> in a terminfo system will put out a literal "50" rather
than busy-waiting for 50 milliseconds.
- <STRONG>o</STRONG> However, if ncurses is configured to support termcap, it may also
+ <STRONG>o</STRONG> However, if ncurses is configured to support termcap, it may also
have been configured to support the BSD-style padding.
In that case, <STRONG>tputs</STRONG> inspects strings passed to it, looking for dig-
<STRONG>tputs("50")</STRONG> in a termcap system may wait for 50 milliseconds rather
than put out a literal "50"
- Note that termcap has nothing analogous to terminfo's <STRONG>sgr</STRONG> string. One
- consequence of this is that termcap applications assume <STRONG>me</STRONG> (terminfo
- <STRONG>sgr0</STRONG>) does not reset the alternate character set. This implementation
+ Note that termcap has nothing analogous to terminfo's <STRONG>sgr</STRONG> string. One
+ consequence of this is that termcap applications assume <STRONG>me</STRONG> (terminfo
+ <STRONG>sgr0</STRONG>) 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.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
</PRE><H3><a name="h3-Standards">Standards</a></H3><PRE>
- These functions are provided for supporting legacy applications, and
+ These functions are provided for supporting legacy applications, and
should not be used in new programs:
<STRONG>o</STRONG> The XSI Curses standard, Issue 4 describes these functions. Howev-
- er, they are marked TO BE WITHDRAWN and may be removed in future
+ er, they are marked TO BE WITHDRAWN and may be removed in future
versions.
<STRONG>o</STRONG> X/Open Curses, Issue 5 (December 2007) marked the termcap interface
(along with <STRONG>vwprintw</STRONG> and <STRONG>vwscanw</STRONG>) as withdrawn.
- Neither the XSI Curses standard nor the SVr4 man pages documented the
- return values of <STRONG>tgetent</STRONG> 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 <STRONG>tgetent</STRONG> returns <STRONG>OK</STRONG>
- or <STRONG>ERR</STRONG>. Because the purpose of these functions is to provide compati-
- bility with the <EM>termcap</EM> library, that is a defect in XCurses, Issue 4,
+ Neither the XSI Curses standard nor the SVr4 man pages documented the
+ return values of <STRONG>tgetent</STRONG> 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 <STRONG>tgetent</STRONG> returns <STRONG>OK</STRONG>
+ or <STRONG>ERR</STRONG>. Because the purpose of these functions is to provide compati-
+ bility with the <EM>termcap</EM> 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 <STRONG>os-</STRONG>
+ ticular, some applications are reported to declare and/or modify <STRONG>os-</STRONG>
<STRONG>peed</STRONG>.
- The comment that only the first two characters of the <STRONG>id</STRONG> parameter are
+ The comment that only the first two characters of the <STRONG>id</STRONG> 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 <STRONG>tgetstr</STRONG>, <STRONG>tgetnum</STRONG> and <STRONG>tgetflag</STRONG>.
- Some applications assume that the termcap interface does not require
+ NUL on the parameter name passed to <STRONG>tgetstr</STRONG>, <STRONG>tgetnum</STRONG> and <STRONG>tgetflag</STRONG>.
+ Some applications assume that the termcap interface does not require
the trailing NUL for the parameter name. Taking into account these is-
sues:
- <STRONG>o</STRONG> As a special case, <STRONG>tgetflag</STRONG> matched against a single-character
- identifier provided that was at the end of the terminal descrip-
+ <STRONG>o</STRONG> As a special case, <STRONG>tgetflag</STRONG> 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-
+ This implementation disallows matches against single-character ca-
pability names.
- <STRONG>o</STRONG> This implementation disallows matches by the termcap interface
+ <STRONG>o</STRONG> This implementation disallows matches by the termcap interface
against extended capability names which are longer than two charac-
ters.
The BSD termcap function <STRONG>tgetent</STRONG> returns the text of a termcap entry in
- the buffer passed as an argument. This library (like other terminfo
+ 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.
</PRE><H3><a name="h3-Other-Compatibility">Other Compatibility</a></H3><PRE>
- This library includes a termcap.h header, for compatibility with other
- implementations. But the header is rarely used because the other im-
+ This library includes a termcap.h header, for compatibility with other
+ implementations. But the header is rarely used because the other im-
plementations are not strictly compatible.
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
+ was written several years before C was standardized. However, there
were two different termcap.h header files in the BSD sources:
- <STRONG>o</STRONG> One was used internally by the <STRONG>jove</STRONG> editor in 2BSD through 4.4BSD.
+ <STRONG>o</STRONG> One was used internally by the <STRONG>jove</STRONG> editor in 2BSD through 4.4BSD.
It defined global symbols for the termcap variables which it used.
- <STRONG>o</STRONG> The other appeared in 4.4BSD Lite Release 2 (mid-1993) as part of
+ <STRONG>o</STRONG> The other appeared in 4.4BSD Lite Release 2 (mid-1993) as part of
<EM>libedit</EM> (also known as the <EM>editline</EM> library). The CSRG source his-
- tory shows that this was added in mid-1992. The <EM>libedit</EM> header
- file was used internally, as a convenience for compiling the <EM>edit-</EM>
+ tory shows that this was added in mid-1992. The <EM>libedit</EM> header
+ file was used internally, as a convenience for compiling the <EM>edit-</EM>
<EM>line</EM> library. It declared function prototypes, but no global vari-
ables.
- The header file from <EM>libedit</EM> was added to NetBSD's termcap library in
+ The header file from <EM>libedit</EM> was added to NetBSD's termcap library in
mid-1994.
- 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
+ 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 <STRONG>const</STRONG> for the function prototypes in the header where one would ex-
- pect the parameters to be read-only. This was a difference versus the
- original BSD termcap. The prototype for <STRONG>tputs</STRONG> also differed, but in
+ pect the parameters to be read-only. This was a difference versus the
+ original BSD termcap. The prototype for <STRONG>tputs</STRONG> also differed, but in
that instance, it was <EM>libedit</EM> which differed from BSD termcap.
A copy of GNU termcap 1.3 was bundled with <EM>bash</EM> in mid-1993, to support
the <STRONG>readline(3)</STRONG> library.
- A termcap.h file was provided in ncurses 1.8.1 (November 1993). That
+ A termcap.h file was provided in ncurses 1.8.1 (November 1993). That
reflected influence by <STRONG>emacs(1)</STRONG> (rather than <STRONG>jove(1)</STRONG>) and GNU termcap:
<STRONG>o</STRONG> it provided declarations for a few global symbols used by <STRONG>emacs</STRONG>
<STRONG>o</STRONG> a prototype for <STRONG>tparam</STRONG> (a GNU termcap feature) was provided.
Later (in mid-1996) the <STRONG>tparam</STRONG> 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
+ 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.
projects / ncurses.git / blobdiff