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31 .\" $Id: term.5,v 1.62 2023/10/21 15:33:10 tom Exp $
32 .TH term 5 2023-10-21 "ncurses 6.4" "File formats"
62 compiled \fIterminfo\fR terminal description
67 Compiled terminfo descriptions are placed under the directory \fB\*d\fP.
68 Two configurations are supported (when building the \fBncurses\fP libraries):
71 A two-level scheme is used to avoid a linear search
72 of a huge \s-1UNIX\s+1 system directory: \fB\*d/c/name\fP where
74 is the name of the terminal, and
76 is the first character of
80 can be found in the file \fB\*d/a/act4\fP.
81 Synonyms for the same terminal are implemented by multiple
82 links to the same compiled file.
85 Using Berkeley database, two types of records are stored:
86 the terminfo data in the same format as stored in a directory tree with
87 the terminfo's primary name as a key,
88 and records containing only aliases pointing to the primary name.
90 If built to write hashed databases,
91 \fBncurses\fP can still read terminfo databases organized as a directory tree,
92 but cannot write entries into the directory tree.
93 It can write (or rewrite) entries in the hashed database.
95 \fBncurses\fP distinguishes the two cases in the TERMINFO and TERMINFO_DIRS
96 environment variable by assuming a directory tree for entries that
97 correspond to an existing directory,
98 and hashed database otherwise.
99 .SS LEGACY STORAGE FORMAT
100 The format has been chosen so that it will be the same on all hardware.
101 An 8 or more bit byte is assumed, but no assumptions about byte ordering
102 or sign extension are made.
104 The compiled file is created with the \fB@TIC@\fP program,
105 and read by the routine \fBsetupterm\fP(3X).
106 The file is divided into six parts:
111 b) \fIterminal names\fP,
113 c) \fIboolean flags\fP,
117 e) \fIstrings\fP, and
119 f) \fIstring table\fP.
122 The \fIheader\fP section begins the file.
123 This section contains six short integers in the format
128 (1) the \fImagic number\fP (octal 0432);
130 (2) the size, in bytes, of the \fIterminal names\fP section;
132 (3) the number of bytes in the \fIboolean flags\fP section;
134 (4) the number of short integers in the \fInumbers\fP section;
136 (5) the number of offsets (short integers) in the \fIstrings\fP section;
138 (6) the size, in bytes, of the \fIstring table\fP.
141 The capabilities in the
145 sections are in the same order as the file <term.h>.
147 Short integers are signed, in the range \-32768 to 32767.
148 They are stored as two 8-bit bytes.
149 The first byte contains the least significant 8 bits of the value,
150 and the second byte contains the most significant 8 bits.
151 (Thus, the value represented is 256*second+first.)
152 This format corresponds to the hardware of the \s-1VAX\s+1
153 and \s-1PDP\s+1-11 (that is, little-endian machines).
154 Machines where this does not correspond to the hardware must read the
155 integers as two bytes and compute the little-endian value.
157 Numbers in a terminal description,
158 whether they are entries in the \fInumbers\fP or \fIstrings\fP table,
159 are positive integers.
160 Boolean flags are treated as positive one-byte integers.
161 In each case, those positive integers represent a terminal capability.
162 The terminal compiler @TIC@ uses negative integers to handle the cases where
163 a capability is not available:
165 If a capability is absent from this terminal,
166 @TIC@ stores a \-1 in the corresponding table.
168 The integer value \-1 is represented by two bytes 0377, 0377.
170 Absent boolean values are represented by the byte 0 (false).
172 If a capability has been canceled from this terminal,
173 @TIC@ stores a \-2 in the corresponding table.
175 The integer value \-2 is represented by two bytes 0377, 0376.
177 The boolean value \-2 is represented by the byte 0376.
180 Other negative values are illegal.
182 The \fIterminal names\fP section comes after the \fIheader\fP.
183 It contains the first line of the terminfo description,
184 listing the various names for the terminal,
185 separated by the \*(``|\*('' character.
186 The \fIterminal names\fP section is terminated
187 with an \s-1ASCII NUL\s+1 character.
189 The \fIboolean flags\fP section has one byte for each flag.
190 Boolean capabilities are either 1 or 0 (true or false)
191 according to whether the terminal supports the given capability or not.
193 Between the \fIboolean flags\fP section and the \fInumber\fP section,
194 a null byte will be inserted, if necessary,
195 to ensure that the \fInumber\fP section begins on an even byte
196 This is a relic of the PDP\-11's word-addressed architecture,
197 originally designed to avoid traps induced
198 by addressing a word on an odd byte boundary.
199 All short integers are aligned on a short word boundary.
201 The \fInumbers\fP section is similar to the \fIboolean flags\fP section.
202 Each capability takes up two bytes,
203 and is stored as a little-endian short integer.
205 The \fIstrings\fP section is also similar.
206 Each capability is stored as a short integer.
207 The capability value is an index into the \fIstring table\fP.
209 The \fIstring table\fP is the last section.
210 It contains all of the values of string capabilities referenced in
211 the \fIstrings\fP section.
212 Each string is null-terminated.
213 Special characters in \*^X or \ec notation are stored in their
214 interpreted form, not the printing representation.
215 Padding information $<nn> and parameter information %x are
216 stored intact in uninterpreted form.
217 .SS EXTENDED STORAGE FORMAT
218 The previous section describes the conventional terminfo binary format.
219 With some minor variations of the offsets (see PORTABILITY),
220 the same binary format is used in all modern UNIX systems.
221 Each system uses a predefined set of boolean, number or string capabilities.
223 The \fBncurses\fP libraries and applications support
224 extended terminfo binary format,
225 allowing users to define capabilities which are loaded at runtime.
227 extension is made possible by using the fact that the other implementations
228 stop reading the terminfo data when they have reached the end of the size given
230 \fBncurses\fP checks the size,
231 and if it exceeds that due to the predefined data,
232 continues to parse according to its own scheme.
234 First, it reads the extended header (5 short integers):
238 count of extended boolean capabilities
241 count of extended numeric capabilities
244 count of extended string capabilities
247 count of the items in extended string table
250 size of the extended string table in bytes
253 The count- and size-values for the extended string table
254 include the extended capability \fInames\fP as well as
255 extended capability \fIvalues\fP.
257 Using the counts and sizes, \fBncurses\fP allocates arrays and reads data
258 for the extended capabilities in the same order as the header information.
260 The extended string table contains values for string capabilities.
261 After the end of these values, it contains the names for each of
262 the extended capabilities in order, e.g., booleans, then numbers and
265 Applications which manipulate terminal data can use the definitions
266 described in \fBterm_variables\fP(3X) which associate the long capability
267 names with members of a \fBTERMTYPE\fP structure.
269 .SS EXTENDED NUMBER FORMAT
270 On occasion, 16-bit signed integers are not large enough.
271 With \fBncurses\fP 6.1, a new format was introduced by making a few changes
272 to the legacy format:
274 a different magic number (octal 01036)
276 changing the type for the \fInumber\fP array from signed 16-bit integers
277 to signed 32-bit integers.
279 To maintain compatibility, the library presents the same data structures
280 to direct users of the \fBTERMTYPE\fP structure as in previous formats.
281 However, that cannot provide callers with the extended numbers.
282 The library uses a similar but hidden data structure \fBTERMTYPE2\fP
283 to provide data for the terminfo functions.
286 Note that it is possible for
288 to expect a different set of capabilities
289 than are actually present in the file.
290 Either the database may have been updated since
293 (resulting in extra unrecognized entries in the file)
294 or the program may have been recompiled more recently
295 than the database was updated
296 (resulting in missing entries).
299 must be prepared for both possibilities \-
300 this is why the numbers and sizes are included.
301 Also, new capabilities must always be added at the end of the lists
302 of boolean, number, and string capabilities.
304 X/Open Curses does not specify a format for the terminfo database.
305 UNIX System V curses used a directory-tree of binary files,
306 one per terminal description.
308 Despite the consistent use of little-endian for numbers and the otherwise
309 self-describing format, it is not wise to count on portability of binary
310 terminfo entries between commercial UNIX versions.
311 The problem is that there
312 are at least three versions of terminfo (under HP\-UX, AIX, and OSF/1) which
313 diverged from System V terminfo after SVr1, and have added extension
314 capabilities to the string table that (in the binary format) collide with
315 System V and XSI Curses extensions.
316 See \fBterminfo\fP(\*n) for detailed
317 discussion of terminfo source compatibility issues.
319 This implementation is by default compatible with the binary
320 terminfo format used by Solaris curses,
321 except in a few less-used details
322 where it was found that the latter did not match X/Open Curses.
323 The format used by the other Unix versions
324 can be matched by building ncurses
325 with different configuration options.
327 The magic number in a binary terminfo file is the first 16-bits (two bytes).
328 Besides making it more reliable for the library to check that a file
330 utilities such as \fBfile\fP(1) also use that to tell what the file-format is.
331 System V defined more than one magic number,
332 with 0433, 0435 as screen-dumps (see \fBscr_dump\fP(5)).
333 This implementation uses 01036 as a continuation of that sequence,
334 but with a different high-order byte to avoid confusion.
335 .SS The TERMTYPE structure
336 Direct access to the \fBTERMTYPE\fP structure is provided for legacy
338 Portable applications should use the \fBtigetflag\fP and related functions
339 described in \fBcurs_terminfo\fP(3X) for reading terminal capabilities.
340 .SS Mixed-case terminal names
341 A small number of terminal descriptions use uppercase characters in
343 If the underlying filesystem ignores the difference between
344 uppercase and lowercase,
345 \fBncurses\fP represents the \*(``first character\*(''
346 of the terminal name used as
347 the intermediate level of a directory tree in (two-character) hexadecimal form.
349 As an example, here is a description for the Lear-Siegler
350 ADM\-3, a popular though rather stupid early terminal:
357 bel=\*^G, clear=\e032$<1>, cr=\*^M, cub1=\*^H, cud1=\*^J,
358 cuf1=\*^L, cup=\eE=%p1%{32}%+%c%p2%{32}%+%c, cuu1=\*^K,
359 home=\*^\*^, ind=\*^J,
363 and a hexadecimal dump of the compiled terminal description:
369 0000 1a 01 10 00 02 00 03 00 82 00 31 00 61 64 6d 33 ........ ..1.adm3
370 0010 61 7c 6c 73 69 20 61 64 6d 33 61 00 00 01 50 00 a|lsi ad m3a...P.
371 0020 ff ff 18 00 ff ff 00 00 02 00 ff ff ff ff 04 00 ........ ........
372 0030 ff ff ff ff ff ff ff ff 0a 00 25 00 27 00 ff ff ........ ..%.\*'...
373 0040 29 00 ff ff ff ff 2b 00 ff ff 2d 00 ff ff ff ff ).....+. ..\-.....
374 0050 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
375 0060 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
376 0070 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
377 0080 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
378 0090 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
379 00a0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
380 00b0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
381 00c0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
382 00d0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
383 00e0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
384 00f0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
385 0100 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
386 0110 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
387 0120 ff ff ff ff ff ff 2f 00 07 00 0d 00 1a 24 3c 31 ....../. .....$<1
388 0130 3e 00 1b 3d 25 70 31 25 7b 33 32 7d 25 2b 25 63 >..=%p1% {32}%+%c
389 0140 25 70 32 25 7b 33 32 7d 25 2b 25 63 00 0a 00 1e %p2%{32} %+%c....
390 0150 00 08 00 0c 00 0b 00 0a 00 ........ .
396 total compiled entries cannot exceed 4096 bytes in the legacy format.
398 total compiled entries cannot exceed 32768 bytes in the extended format.
400 the name field cannot exceed 128 bytes.
402 Compiled entries are limited to 32768 bytes because offsets into the
403 \fIstrings table\fP use two-byte integers.
404 The legacy format could have supported 32768-byte entries,
405 but was limited a virtual memory page's 4096 bytes.
409 compiled terminal description database
413 extended terminfo format for ncurses 5.0
415 hashed database support for ncurses 5.6
417 extended number support for ncurses 6.1
421 documented legacy terminfo format, e.g., from \fIpcurses\fP.
424 \fB\%curs_terminfo\fP(3X),
425 \fB\%terminfo\fP(\*n)