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NAME | DESCRIPTION | FILES | PORTABILITY | EXAMPLES | AUTHORS | SEE ALSO | COLOPHON |
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term(5) File formats term(5)
term - compiled terminfo terminal description
tic(1) compiles a terminfo terminal type description, and
setupterm(3X) reads it. A compiled description may be stored in a
file or in a database of, potentially, many such descriptions.
Further, a compiled description may be in one of two formats: one
similar to that used by System V, and a newer, extensible format
employed exclusively by ncurses.
Storage Location
Compiled terminfo descriptions are placed under the directory
terminfo. One of two configurations is selected when building the
ncurses libraries.
directory tree
A two-level scheme is used to avoid a linear search of a huge
Unix system directory: terminfo/c/name where name is the name
of the terminal, and c is the first character of name. Thus,
the compiled description of terminal type “act4” is found in
the file terminfo/a/act4. Synonyms for the same terminal are
implemented by multiple links to the same compiled file.
hashed database
Using the Berkeley database API, two types of records are
stored: the terminfo data in the same format as that stored
in a directory tree with the terminal's primary type 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 a hashed database otherwise.
Legacy Storage Format
The format has been chosen so that it will be the same on all
hardware. A byte of at least eight bits' width is assumed, but no
assumptions about bit ordering or sign extension are made.
The file is divided into six parts:
(a) header,
(b) terminal names,
(c) Boolean flags,
(d) numbers,
(e) strings, and
(f) a 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 terminal names section;
(3) the number of bytes in the Boolean flags 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.
The capabilities in the Boolean flags, numbers, and strings
sections are in the same order as in the header file term.h.
Short integers are signed, in the range -32768 to 32767, and
stored in little-endian format.
Numbers in a terminal description, whether they are entries in the
numbers or strings table, are positive integers. Boolean flags
are treated as positive one-byte integers. In each case, those
positive integers represent a terminal capability. The terminal
compiler tic uses negative integers to handle the cases where a
capability is not available:
• If a capability is absent from this terminal, tic stores a -1
in the corresponding table.
The integer value -1 is represented by two bytes 0377, 0377.
Absent Boolean values are represented by the byte 0 (false).
• If a capability has been canceled from this terminal, tic
stores a -2 in the corresponding table.
The integer value -2 is represented by two bytes 0377, 0376.
The Boolean value -2 is represented by the byte 0376.
• Other negative values are illegal.
The terminal names section comes after the header. It contains
the first line of the terminfo description, listing the various
names for the terminal, separated by the “|” character. The
terminal names section is terminated with an ASCII NUL character.
The Boolean flags section has one byte for each flag. Boolean
capabilities are either 1 or 0 (true or false) according to
whether the terminal supports the given capability or not.
Between the Boolean flags 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 to avoid 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 Boolean flags section. Each
capability takes up two bytes, and is stored as a little-endian
short integer.
The strings section is also similar. Each capability is stored as
a short integer. The capability value is an index into the string
table.
The string table is the last section. It contains all of the
values of string capabilities referenced in the strings section.
Each string is null-terminated. 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.
Extended Storage Format
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 standard set of Boolean, numeric, or
string capabilities.
The ncurses libraries and applications support extended terminfo
binary format, allowing users to define capabilities that are
loaded at runtime. This extension is made possible by using the
fact that the other implementations stop reading the terminfo data
when they reach the end of the size given in the header. ncurses
checks the size, and if it exceeds that specified in the header,
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) count of the items in extended string table
(5) size of the extended string table in bytes
The count- and size-values for the extended string table include
the extended capability names as well as extended capability
values.
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: Boolean, numeric, and string.
By storing terminal descriptions in this way, ncurses is able to
provide a database useful with legacy applications, as well as
providing data for applications that require more information
about a terminal type than was anticipated by X/Open Curses. See
user_caps(5) for an overview of the way ncurses uses this extended
information.
Applications that manipulate terminal data can use the definitions
described in term_variables(3X) associating the long capability
names with members of a TERMTYPE structure.
Extended Number Format
On occasion, 16-bit signed integers are not large enough. ncurses
6.1 introduced a new format by making a few changes to the legacy
format:
• a different magic number (octal 01036)
• 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
structures 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.
terminfo
compiled terminal description database
setupterm
Note that it is possible for setupterm to expect a different set
of capabilities than are actually present in the file. Either the
database may have been updated since setupterm was recompiled
(resulting 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 Boolean, number, and string
capabilities.
Binary Format
X/Open Curses does not specify a format for the terminfo database.
System V curses used a directory-tree of binary files, one per
terminal description.
Despite the consistent use of little-endian 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) each of which diverged
from System V terminfo after SVr1, and added extension
capabilities to the string table that (in the binary format)
collide with System V and X/Open Curses extensions. See
terminfo(5) for detailed discussion of terminfo source
compatibility issues.
This implementation is by default compatible with the binary term‐
info format used by Solaris curses, except in a few less-used
details where it was found that the latter did not match X/Open
Curses. The format used by the other Unix versions can be matched
by building ncurses with different configuration options.
Magic Codes
The magic number in a binary terminfo file is the first 16 bits
(two bytes). Besides making it more reliable for the library to
check that a file is terminfo, utilities such as file(1) also use
that to tell what the file-format is. System V defined more than
one magic number, with 0433, 0435 as screen-dumps (see
scr_dump(5)). This implementation uses 01036 as a continuation of
that sequence, but with a different high-order byte to avoid
confusion.
The TERMTYPE Structure
Direct access to the TERMTYPE structure is provided for legacy
applications. Portable applications should use tigetflag(3X) and
related functions to read terminal capabilities.
Mixed-case Terminal Names
A small number of terminal descriptions use uppercase characters
in their names. If the underlying file system ignores the
difference between uppercase and lowercase, ncurses represents the
“first character” of the terminal name used as the intermediate
level of a directory tree in (two-character) hexadecimal form.
Limits
ncurses stores compiled terminal descriptions in three related
formats, described in the subsections
• Legacy Storage Format, and
• Extended Storage Format, and
• Extended Number Format.
The legacy storage format and the extended number format differ by
the types of numeric capability that they can store (for example,
16- versus 32-bit integers). The extended storage format
introduced by ncurses 5.0 adds data to either of these formats.
Some limitations apply:
• total compiled entries cannot exceed 4096 bytes in the legacy
format.
• total compiled entries cannot exceed 32768 bytes in the
extended format.
• the name field cannot exceed 128 bytes.
Compiled entries are limited to 32768 bytes because offsets into
the strings table use two-byte integers. The legacy format could
have supported 32768-byte entries, but was limited to a virtual
memory page's 4096 bytes.
Here is a terminfo description of the Lear-Siegler ADM-3, a
popular though rather stupid early terminal.
adm3a|lsi adm3a,
am,
cols#80, lines#24,
bel=^G, clear=\032$<1>, cr=^M, cub1=^H, cud1=^J,
cuf1=^L, cup=\E=%p1%{32}%+%c%p2%{32}%+%c, cuu1=^K,
home=^^, ind=^J,
A hexadecimal dump of its compiled terminal description (in legacy
format) follows.
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 ........ .
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 (that used by pcurses).
curses(3X), curs_terminfo(3X), terminfo(5), user_caps(5)
This page is part of the ncurses (new curses) project.
Information about the project can be found at
⟨https://invisible-island.net/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to bug-ncurses@gnu.org.
This page was obtained from the tarball ncurses-6.6.tar.gz fetched
from ⟨https://ftp.gnu.org/gnu/ncurses/⟩ on 2026-01-16. If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for the
page, or you have corrections or improvements to the information
in this COLOPHON (which is not part of the original manual page),
send a mail to man-pages@man7.org
ncurses @NCURSES_MAJOR@.@NCU... 2025-08-16 term(5)
Pages that refer to this page: tic(1m), terminfo(5), term(7)
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HTML rendering created 2026-01-16 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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