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30 * @Id: curs_termcap.3x,v 1.49 2021/04/03 21:17:09 tom Exp @
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42 <H1 class="no-header">curs_termcap 3x</H1>
44 <STRONG><A HREF="curs_termcap.3x.html">curs_termcap(3x)</A></STRONG> <STRONG><A HREF="curs_termcap.3x.html">curs_termcap(3x)</A></STRONG>
49 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
50 <STRONG>PC</STRONG>, <STRONG>UP</STRONG>, <STRONG>BC</STRONG>, <STRONG>ospeed</STRONG>, <STRONG>tgetent</STRONG>, <STRONG>tgetflag</STRONG>, <STRONG>tgetnum</STRONG>, <STRONG>tgetstr</STRONG>, <STRONG>tgoto</STRONG>, <STRONG>tputs</STRONG> -
51 <STRONG>curses</STRONG> emulation of termcap
54 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
55 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
56 <STRONG>#include</STRONG> <STRONG><term.h></STRONG>
58 <STRONG>extern</STRONG> <STRONG>char</STRONG> <STRONG>PC;</STRONG>
59 <STRONG>extern</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <STRONG>UP;</STRONG>
60 <STRONG>extern</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG> <STRONG>BC;</STRONG>
61 <STRONG>extern</STRONG> <STRONG>short</STRONG> <STRONG>ospeed;</STRONG>
63 <STRONG>int</STRONG> <STRONG>tgetent(char</STRONG> <STRONG>*</STRONG><EM>bp</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>name</EM><STRONG>);</STRONG>
64 <STRONG>int</STRONG> <STRONG>tgetflag(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>id</EM><STRONG>);</STRONG>
65 <STRONG>int</STRONG> <STRONG>tgetnum(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>id</EM><STRONG>);</STRONG>
66 <STRONG>char</STRONG> <STRONG>*tgetstr(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>id</EM><STRONG>,</STRONG> <STRONG>char</STRONG> <STRONG>**</STRONG><EM>area</EM><STRONG>);</STRONG>
67 <STRONG>char</STRONG> <STRONG>*tgoto(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>cap</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>col</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>row</EM><STRONG>);</STRONG>
68 <STRONG>int</STRONG> <STRONG>tputs(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>str</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>affcnt</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <STRONG>(*</STRONG><EM>putc</EM><STRONG>)(int));</STRONG>
71 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
72 These routines are included as a conversion aid for programs that use
73 the <EM>termcap</EM> library. Their parameters are the same, but the routines
74 are emulated using the <EM>terminfo</EM> database. Thus, they can only be used
75 to query the capabilities of entries for which a terminfo entry has
79 </PRE><H3><a name="h3-INITIALIZATION">INITIALIZATION</a></H3><PRE>
80 The <STRONG>tgetent</STRONG> routine loads the entry for <EM>name</EM>. It returns:
84 0 if there is no such entry (or that it is a generic type, having
85 too little information for curses applications to run), and
87 -1 if the terminfo database could not be found.
89 This differs from the <EM>termcap</EM> library in two ways:
91 <STRONG>o</STRONG> The emulation ignores the buffer pointer <EM>bp</EM>. The <EM>termcap</EM> li-
92 brary would store a copy of the terminal description in the area
93 referenced by this pointer. However, ncurses stores its termi-
94 nal descriptions in compiled binary form, which is not the same
97 <STRONG>o</STRONG> There is a difference in return codes. The <EM>termcap</EM> library does
98 not check if the terminal description is marked with the <EM>generic</EM>
99 capability, or if the terminal description has cursor-address-
103 </PRE><H3><a name="h3-CAPABILITY-VALUES">CAPABILITY VALUES</a></H3><PRE>
104 The <STRONG>tgetflag</STRONG> routine gets the boolean entry for <EM>id</EM>, or zero if it is
107 The <STRONG>tgetnum</STRONG> routine gets the numeric entry for <EM>id</EM>, or -1 if it is not
110 The <STRONG>tgetstr</STRONG> routine returns the string entry for <EM>id</EM>, or zero if it is
111 not available. Use <STRONG>tputs</STRONG> to output the returned string. The <EM>area</EM> pa-
112 rameter is used as follows:
114 <STRONG>o</STRONG> It is assumed to be the address of a pointer to a buffer managed
115 by the calling application.
117 <STRONG>o</STRONG> However, ncurses checks to ensure that <STRONG>area</STRONG> is not NULL, and al-
118 so that the resulting buffer pointer is not NULL. If either
119 check fails, the <EM>area</EM> parameter is ignored.
121 <STRONG>o</STRONG> If the checks succeed, ncurses also copies the return value to
122 the buffer pointed to by <EM>area</EM>, and the <EM>area</EM> value will be updat-
123 ed to point past the null ending this value.
125 <STRONG>o</STRONG> The return value itself is an address in the terminal descrip-
126 tion which is loaded into memory.
128 Only the first two characters of the <STRONG>id</STRONG> parameter of <STRONG>tgetflag</STRONG>, <STRONG>tgetnum</STRONG>
129 and <STRONG>tgetstr</STRONG> are compared in lookups.
132 </PRE><H3><a name="h3-FORMATTING-CAPABILITIES">FORMATTING CAPABILITIES</a></H3><PRE>
133 The <STRONG>tgoto</STRONG> routine expands the given capability using the parameters.
135 <STRONG>o</STRONG> Because the capability may have padding characters, the output of
136 <STRONG>tgoto</STRONG> should be passed to <STRONG>tputs</STRONG> rather than some other output func-
137 tion such as <STRONG>printf</STRONG>.
139 <STRONG>o</STRONG> While <STRONG>tgoto</STRONG> is assumed to be used for the two-parameter cursor po-
140 sitioning capability, termcap applications also use it for single-
141 parameter capabilities.
143 Doing this shows a quirk in <STRONG>tgoto</STRONG>: most hardware terminals use cur-
144 sor addressing with <EM>row</EM> first, but the original developers of the
145 termcap interface chose to put the <EM>column</EM> parameter first. The
146 <STRONG>tgoto</STRONG> function swaps the order of parameters. It does this also
147 for calls requiring only a single parameter. In that case, the
148 first parameter is merely a placeholder.
150 <STRONG>o</STRONG> Normally the ncurses library is compiled with terminfo support. In
151 that case, <STRONG>tgoto</STRONG> uses <STRONG><A HREF="curs_terminfo.3x.html">tparm(3x)</A></STRONG> (a more capable formatter).
153 However, <STRONG>tparm</STRONG> is not a <EM>termcap</EM> feature, and portable <EM>termcap</EM> ap-
154 plications should not rely upon its availability.
156 The <STRONG>tputs</STRONG> routine is described on the <STRONG><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG> manual page.
157 It can retrieve capabilities by either termcap or terminfo name.
160 </PRE><H3><a name="h3-GLOBAL-VARIABLES">GLOBAL VARIABLES</a></H3><PRE>
161 The variables <STRONG>PC</STRONG>, <STRONG>UP</STRONG> and <STRONG>BC</STRONG> are set by <STRONG>tgetent</STRONG> to the terminfo entry's
162 data for <STRONG>pad_char</STRONG>, <STRONG>cursor_up</STRONG> and <STRONG>backspace_if_not_bs</STRONG>, respectively. <STRONG>UP</STRONG>
163 is not used by ncurses. <STRONG>PC</STRONG> is used in the <STRONG>tdelay_output</STRONG> function. <STRONG>BC</STRONG>
164 is used in the <STRONG>tgoto</STRONG> emulation. The variable <STRONG>ospeed</STRONG> is set by ncurses
165 in a system-specific coding to reflect the terminal speed.
168 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
169 Except where explicitly noted, routines that return an integer return
170 <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> (SVr4 only specifies "an integer value other
171 than <STRONG>ERR</STRONG>") upon successful completion.
173 Routines that return pointers return <STRONG>NULL</STRONG> on error.
176 </PRE><H2><a name="h2-BUGS">BUGS</a></H2><PRE>
177 If you call <STRONG>tgetstr</STRONG> to fetch <STRONG>ca</STRONG> or any other parameterized string, be
178 aware that it will be returned in terminfo notation, not the older and
179 not-quite-compatible termcap notation. This will not cause problems if
180 all you do with it is call <STRONG>tgoto</STRONG> or <STRONG>tparm</STRONG>, which both expand terminfo-
181 style strings as terminfo. (The <STRONG>tgoto</STRONG> function, if configured to sup-
182 port termcap, will check if the string is indeed terminfo-style by
183 looking for "%p" parameters or "$<..>" delays, and invoke a termcap-
184 style parser if the string does not appear to be terminfo).
186 Because terminfo conventions for representing padding in string capa-
187 bilities differ from termcap's, users can be surprised:
189 <STRONG>o</STRONG> <STRONG>tputs("50")</STRONG> in a terminfo system will put out a literal "50" rather
190 than busy-waiting for 50 milliseconds.
192 <STRONG>o</STRONG> However, if ncurses is configured to support termcap, it may also
193 have been configured to support the BSD-style padding.
195 In that case, <STRONG>tputs</STRONG> inspects strings passed to it, looking for dig-
196 its at the beginning of the string.
198 <STRONG>tputs("50")</STRONG> in a termcap system may wait for 50 milliseconds rather
199 than put out a literal "50"
201 Note that termcap has nothing analogous to terminfo's <STRONG>sgr</STRONG> string. One
202 consequence of this is that termcap applications assume <STRONG>me</STRONG> (terminfo
203 <STRONG>sgr0</STRONG>) does not reset the alternate character set. This implementation
204 checks for, and modifies the data shown to the termcap interface to ac-
205 commodate termcap's limitation in this respect.
208 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
210 </PRE><H3><a name="h3-Standards">Standards</a></H3><PRE>
211 These functions are provided for supporting legacy applications, and
212 should not be used in new programs:
214 <STRONG>o</STRONG> The XSI Curses standard, Issue 4 describes these functions. Howev-
215 er, they are marked TO BE WITHDRAWN and may be removed in future
218 <STRONG>o</STRONG> X/Open Curses, Issue 5 (December 2007) marked the termcap interface
219 (along with <STRONG>vwprintw</STRONG> and <STRONG>vwscanw</STRONG>) as withdrawn.
221 Neither the XSI Curses standard nor the SVr4 man pages documented the
222 return values of <STRONG>tgetent</STRONG> correctly, though all three were in fact re-
223 turned ever since SVr1. In particular, an omission in the XSI Curses
224 documentation has been misinterpreted to mean that <STRONG>tgetent</STRONG> returns <STRONG>OK</STRONG>
225 or <STRONG>ERR</STRONG>. Because the purpose of these functions is to provide compati-
226 bility with the <EM>termcap</EM> library, that is a defect in XCurses, Issue 4,
227 Version 2 rather than in ncurses.
230 </PRE><H3><a name="h3-Compatibility-with-BSD-Termcap">Compatibility with BSD Termcap</a></H3><PRE>
231 External variables are provided for support of certain termcap applica-
232 tions. However, termcap applications' use of those variables is poorly
233 documented, e.g., not distinguishing between input and output. In par-
234 ticular, some applications are reported to declare and/or modify <STRONG>os-</STRONG>
235 <STRONG>peed</STRONG>.
237 The comment that only the first two characters of the <STRONG>id</STRONG> parameter are
238 used escapes many application developers. The original BSD 4.2 termcap
239 library (and historical relics thereof) did not require a trailing null
240 NUL on the parameter name passed to <STRONG>tgetstr</STRONG>, <STRONG>tgetnum</STRONG> and <STRONG>tgetflag</STRONG>.
241 Some applications assume that the termcap interface does not require
242 the trailing NUL for the parameter name. Taking into account these is-
245 <STRONG>o</STRONG> As a special case, <STRONG>tgetflag</STRONG> matched against a single-character
246 identifier provided that was at the end of the terminal descrip-
247 tion. You should not rely upon this behavior in portable programs.
248 This implementation disallows matches against single-character ca-
251 <STRONG>o</STRONG> This implementation disallows matches by the termcap interface
252 against extended capability names which are longer than two charac-
255 The BSD termcap function <STRONG>tgetent</STRONG> returns the text of a termcap entry in
256 the buffer passed as an argument. This library (like other terminfo
257 implementations) does not store terminal descriptions as text. It sets
258 the buffer contents to a null-terminated string.
261 </PRE><H3><a name="h3-Other-Compatibility">Other Compatibility</a></H3><PRE>
262 This library includes a termcap.h header, for compatibility with other
263 implementations. But the header is rarely used because the other im-
264 plementations are not strictly compatible.
266 The original BSD termcap (through 4.3BSD) had no header file which gave
267 function prototypes, because that was a feature of ANSI C. BSD termcap
268 was written several years before C was standardized. However, there
269 were two different termcap.h header files in the BSD sources:
271 <STRONG>o</STRONG> One was used internally by the <EM>jove</EM> editor in 2BSD through 4.4BSD.
272 It defined global symbols for the termcap variables which it used.
274 <STRONG>o</STRONG> The other appeared in 4.4BSD Lite Release 2 (mid-1993) as part of
275 <EM>libedit</EM> (also known as the <EM>editline</EM> library). The CSRG source his-
276 tory shows that this was added in mid-1992. The <EM>libedit</EM> header
277 file was used internally, as a convenience for compiling the <EM>edit-</EM>
278 <EM>line</EM> library. It declared function prototypes, but no global vari-
281 The header file from <EM>libedit</EM> was added to NetBSD's termcap library in
284 Meanwhile, GNU termcap was under development, starting in 1990. The
285 first release (termcap 1.0) in 1991 included a termcap.h header. The
286 second release (termcap 1.1) in September 1992 modified the header to
287 use <STRONG>const</STRONG> for the function prototypes in the header where one would ex-
288 pect the parameters to be read-only. This was a difference versus the
289 original BSD termcap. The prototype for <STRONG>tputs</STRONG> also differed, but in
290 that instance, it was <EM>libedit</EM> which differed from BSD termcap.
292 A copy of GNU termcap 1.3 was bundled with <EM>bash</EM> in mid-1993, to support
293 the <EM>readline</EM> library.
295 A termcap.h file was provided in ncurses 1.8.1 (November 1993). That
296 reflected influence by <EM>emacs</EM> (rather than <EM>jove</EM>) and GNU termcap:
298 <STRONG>o</STRONG> it provided declarations for a few global symbols used by <EM>emacs</EM>
300 <STRONG>o</STRONG> it provided function prototypes (using <STRONG>const</STRONG>).
302 <STRONG>o</STRONG> a prototype for <STRONG>tparam</STRONG> (a GNU termcap feature) was provided.
304 Later (in mid-1996) the <STRONG>tparam</STRONG> function was removed from ncurses. As a
305 result, there are differences between any of the four implementations,
306 which must be taken into account by programs which can work with all
307 termcap library interfaces.
310 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
311 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG>putc(3)</STRONG>, <STRONG><A HREF="term_variables.3x.html">term_variables(3x)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>.
313 https://invisible-island.net/ncurses/tctest.html
317 <STRONG><A HREF="curs_termcap.3x.html">curs_termcap(3x)</A></STRONG>
321 <li><a href="#h2-NAME">NAME</a></li>
322 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
323 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
325 <li><a href="#h3-INITIALIZATION">INITIALIZATION</a></li>
326 <li><a href="#h3-CAPABILITY-VALUES">CAPABILITY VALUES</a></li>
327 <li><a href="#h3-FORMATTING-CAPABILITIES">FORMATTING CAPABILITIES</a></li>
328 <li><a href="#h3-GLOBAL-VARIABLES">GLOBAL VARIABLES</a></li>
331 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
332 <li><a href="#h2-BUGS">BUGS</a></li>
333 <li><a href="#h2-PORTABILITY">PORTABILITY</a>
335 <li><a href="#h3-Standards">Standards</a></li>
336 <li><a href="#h3-Compatibility-with-BSD-Termcap">Compatibility with BSD Termcap</a></li>
337 <li><a href="#h3-Other-Compatibility">Other Compatibility</a></li>
340 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>