term(5) — Linux manual page


term(5)                      File Formats Manual                     term(5)

NAME         top

       term - format of compiled term file.

SYNOPSIS         top


DESCRIPTION         top

       Compiled terminfo descriptions are placed under the directory
       @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: @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 @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 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
            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(3X).  The file is divided into six parts:

            a) header,

            b) terminal names,

            c) boolean flags,

            d) numbers,

            e) strings, and

            f) 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

            (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 the file <term.h>.

       Short integers are signed, in the range -32768 to 32767.  They are
       stored as 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.)  This format corresponds to the hardware 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.

       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

       The strings section is also similar.  Each capability is stored as a
       short integer.  The capability value is an index into the string

       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.

       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

       The ncurses libraries and applications support extended terminfo
       binary format, allowing users to define capabilities 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)  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

       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 was introduced 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.

PORTABILITY         top

       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 has been 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.
       UNIX System V curses used a directory-tree of binary files, one per
       terminal description.

       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 discussion of
       terminfo source compatibility issues.

       This implementation is by default compatible with the binary terminfo
       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 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 the tigetflag and
       related functions described in curs_terminfo(3X) for reading terminal

   Mixed-case terminal names
       A small number of terminal descriptions use uppercase characters in
       their names.  If the underlying filesystem 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.

EXAMPLE         top

       As an example, here is a description for the Lear-Siegler ADM-3, a
       popular though rather stupid early terminal:

           adm3a|lsi adm3a,
                   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                       ........ .

LIMITS         top

       Some limitations:

       •   total compiled entries cannot exceed 4096 bytes in the legacy

       •   total compiled entries cannot exceed 32768 bytes in the extended

       •   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 a virtual memory page's
       4096 bytes.

FILES         top

       @TERMINFO@/*/* compiled terminal capability data base

SEE ALSO         top

       curses(3X), terminfo(5).

AUTHORS         top

       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 pcurses.

COLOPHON         top

       This page is part of the ncurses (new curses) project.  Information
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       ⟨https://www.gnu.org/software/ncurses/ncurses.html⟩.  If you have a
       bug report for this manual page, send it to
       bug-ncurses-request@gnu.org.  This page was obtained from the
       project's upstream Git mirror of the CVS repository
       ⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2020-11-01.  (At that
       time, the date of the most recent commit that was found in the repos‐
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       the original manual page), send a mail to man-pages@man7.org


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