term(5) term(5)
term - format of compiled term file.
term
Compiled terminfo descriptions are placed under the direc-
tory /usr/share/terminfo. Two configurations are sup-
ported (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/share/ter-
minfo/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/share/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 terminfo data in the same format as
stored in a directory tree with the terminfo's pri-
mary name as a key, and records containing only
aliases pointing to the primary name.
If built to write hashed databases, ncurses can still
read terminfo 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 TERMINFO_DIRS environment variable by assuming a
directory tree for entries that correspond to an
existing directory, and hashed database 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 ordering or sign extension are
made.
The compiled file is created with the tic program, and
read by the routine setupterm. The file is divided into
six parts: the header, terminal names, boolean flags, num-
bers, 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 sec-
tion;
(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*second+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 hard-
ware of the VAX and PDP-11 (that is, little-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 vari-
ous names for the terminal, separated by the `|' charac-
ter. The section is terminated with an ASCII NUL charac-
ter.
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 beginning of the
string table. Special characters in ^X or \c notation are
stored in their interpreted form, not the printing repre-
sentation. Padding information $<nn> and parameter infor-
mation %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 capabili-
ties which are loaded at runtime. 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 capa-
bilities. 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.
Note that it is possible for setupterm to expect a differ-
ent set of capabilities than are actually present in the
file. Either the database may have been updated since
setupterm has been recompiled (resulting in extra unrecog-
nized 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 boolean,
number, and string capabilities.
Despite the consistent use of little-endian for numbers
and the otherwise 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 discus-
sion of terminfo source compatibility issues.
As an example, here is a hex dump of the description for
the Lear-Siegler ADM-3, a popular 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,
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: total compiled entries cannot exceed
4096 bytes. The name field cannot exceed 128 bytes.
/usr/share/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
Eric S. Raymond
term(5)