term(5) term(5)
term - format of compiled term file.
term
Compiled terminfo descriptions are placed under the directory
/usr/local/ncurses/lib/terminfo. Two configurations are supported
(when building the ncurses libraries):
directory tree
A two-level scheme is used to avoid a linear search of a huge UNIX
system directory: /usr/local/ncurses/lib/terminfo/c/name where
name is the name of the terminal, and c is the first character of
name. Thus, act4 can be found in the file
/usr/local/ncurses/lib/terminfo/a/act4. Synonyms for the same
terminal are implemented by multiple links to the same compiled
file.
hashed database
Using Berkeley database, two types of records are stored: the ter-
minfo data in the same format as stored in a directory tree with
the terminfo's primary name as a key, and records containing only
aliases pointing to the primary name.
If built to write hashed databases, ncurses can still read ter-
minfo databases organized as a directory tree, but cannot write
entries into the directory tree. It can write (or rewrite)
entries in the hashed database.
ncurses distinguishes the two cases in the TERMINFO and TER-
MINFO_DIRS environment variable by assuming a directory tree for
entries that correspond to an existing directory, and hashed data-
base otherwise.
The format has been chosen so that it will be the same on all hardware.
An 8 or more bit byte is assumed, but no assumptions about byte order-
ing or sign extension are made.
The compiled file is created with the tic program, and read by the rou-
tine setupterm(3x). The file is divided into six parts: the header,
terminal names, boolean flags, numbers, strings, and string table.
The header section begins the file. This section contains six short
integers in the format described below. These integers are
(1) the magic number (octal 0432);
(2) the size, in bytes, of the names section;
(3) the number of bytes in the boolean section;
(4) the number of short integers in the numbers section;
(5) the number of offsets (short integers) in the strings section;
(6) the size, in bytes, of the string table.
Short integers are stored in two 8-bit bytes. The first byte contains
the least significant 8 bits of the value, and the second byte contains
the most significant 8 bits. (Thus, the value represented is 256*sec-
ond+first.) The value -1 is represented by the two bytes 0377, 0377;
other negative values are illegal. This value generally means that the
corresponding capability is missing from this terminal. Note that this
format corresponds to the hardware of the VAX and PDP-11 (that is, lit-
tle-endian machines). Machines where this does not correspond to the
hardware must read the integers as two bytes and compute the little-
endian value.
The terminal names section comes next. It contains the first line of
the terminfo description, listing the various names for the terminal,
separated by the "|" character. The section is terminated with an
ASCII NUL character.
The boolean flags have one byte for each flag. This byte is either 0
or 1 as the flag is present or absent. The capabilities are in the
same order as the file <term.h>.
Between the boolean section and the number section, a null byte will be
inserted, if necessary, to ensure that the number section begins on an
even byte (this is a relic of the PDP-11's word-addressed architecture,
originally designed in to avoid IOT traps induced by addressing a word
on an odd byte boundary). All short integers are aligned on a short
word boundary.
The numbers section is similar to the flags section. Each capability
takes up two bytes, and is stored as a little-endian short integer. If
the value represented is -1, the capability is taken to be missing.
The strings section is also similar. Each capability is stored as a
short integer, in the format above. A value of -1 means the capability
is missing. Otherwise, the value is taken as an offset from the begin-
ning of the string table. Special characters in ^X or \c notation are
stored in their interpreted form, not the printing representation.
Padding information $<nn> and parameter information %x are stored
intact in uninterpreted form.
The final section is the string table. It contains all the values of
string capabilities referenced in the string section. Each string is
null terminated.
The previous section describes the conventional terminfo binary format.
With some minor variations of the offsets (see PORTABILITY), the same
binary format is used in all modern UNIX systems. Each system uses a
predefined set of boolean, number or string capabilities.
The ncurses libraries and applications support extended terminfo binary
format, allowing users to define capabilities which are loaded at run-
time. This extension is made possible by using the fact that the other
implementations stop reading the terminfo data when they have reached
the end of the size given in the header. ncurses checks the size, and
if it exceeds that due to the predefined data, continues to parse
according to its own scheme.
First, it reads the extended header (5 short integers):
(1) count of extended boolean capabilities
(2) count of extended numeric capabilities
(3) count of extended string capabilities
(4) size of the extended string table in bytes.
(5) last offset of the extended string table in bytes.
Using the counts and sizes, ncurses allocates arrays and reads data for
the extended capabilities in the same order as the header information.
The extended string table contains values for string capabilities.
After the end of these values, it contains the names for each of the
extended capabilities in order, e.g., booleans, then numbers and
finally strings.
Applications which manipulate terminal data can use the definitions
described in term_variables(3x) which associate the long capability
names with members of a TERMTYPE structure.
On occasion, 16-bit signed integers are not large enough. With ncurses
6.1, a new format is introduced by making a few changes to the legacy
format:
o a different magic number (0542)
o changing the type for the number array from signed 16-bit integers
to signed 32-bit integers.
To maintain compatibility, the library presents the same data struc-
tures to direct users of the TERMTYPE structure as in previous formats.
However, that cannot provide callers with the extended numbers. The
library uses a similar but hidden data structure TERMTYPE2 to provide
data for the terminfo functions.
Note that it is possible for setupterm to expect a different set of
capabilities than are actually present in the file. Either the data-
base may have been updated since setupterm has been recompiled (result-
ing in extra unrecognized entries in the file) or the program may have
been recompiled more recently than the database was updated (resulting
in missing entries). The routine setupterm must be prepared for both
possibilities - this is why the numbers and sizes are included. Also,
new capabilities must always be added at the end of the lists of bool-
ean, number, and string capabilities.
Despite the consistent use of little-endian for numbers and the other-
wise self-describing format, it is not wise to count on portability of
binary terminfo entries between commercial UNIX versions. The problem
is that there are at least three versions of terminfo (under HP-UX,
AIX, and OSF/1) which diverged from System V terminfo after SVr1, and
have added extension capabilities to the string table that (in the
binary format) collide with System V and XSI Curses extensions. See
terminfo(5) for detailed discussion of terminfo source compatibility
issues.
Direct access to the TERMTYPE structure is provided for legacy applica-
tions. Portable applications should use the tigetflag and related
functions described in curs_terminfo(3x) for reading terminal capabili-
ties.
As an example, here is a description for the Lear-Siegler ADM-3, a pop-
ular though rather stupid early terminal:
adm3a|lsi adm3a,
am,
cols#80, lines#24,
bel=^G, clear= 32$<1>, cr=^M, cub1=^H, cud1=^J,
cuf1=^L, cup=\E=%p1%{32}%+%c%p2%{32}%+%c, cuu1=^K,
home=^^, ind=^J,
and a hexadecimal dump of the compiled terminal description:
0000 1a 01 10 00 02 00 03 00 82 00 31 00 61 64 6d 33 ........ ..1.adm3
0010 61 7c 6c 73 69 20 61 64 6d 33 61 00 00 01 50 00 a|lsi ad m3a...P.
0020 ff ff 18 00 ff ff 00 00 02 00 ff ff ff ff 04 00 ........ ........
0030 ff ff ff ff ff ff ff ff 0a 00 25 00 27 00 ff ff ........ ..%.'...
0040 29 00 ff ff ff ff 2b 00 ff ff 2d 00 ff ff ff ff ).....+. ..-.....
0050 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0060 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0070 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0080 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0090 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00a0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00b0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00c0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00d0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00e0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
00f0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0100 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0110 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ........ ........
0120 ff ff ff ff ff ff 2f 00 07 00 0d 00 1a 24 3c 31 ....../. .....$<1
0130 3e 00 1b 3d 25 70 31 25 7b 33 32 7d 25 2b 25 63 >..=%p1% {32}%+%c
0140 25 70 32 25 7b 33 32 7d 25 2b 25 63 00 0a 00 1e %p2%{32} %+%c....
0150 00 08 00 0c 00 0b 00 0a 00 ........ .
Some limitations:
o total compiled entries cannot exceed 4096 bytes in the legacy for-
mat.
o total compiled entries cannot exceed 32768 bytes in the extended
format.
o the name field cannot exceed 128 bytes.
/usr/local/ncurses/lib/terminfo/*/* compiled terminal capability
data base
curses(3x), terminfo(5).
Thomas E. Dickey
extended terminfo format for ncurses 5.0
hashed database support for ncurses 5.6
extended number support for ncurses 6.1
Eric S. Raymond
documented legacy terminfo format, e.g., from pdcurses.
term(5)