term(5) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | PORTABILITY | EXAMPLE | LIMITS | FILES | SEE ALSO | AUTHORS | COLOPHON

term(5)                    File Formats Manual                   term(5)

NAME         top

       term - format of compiled term file.

SYNOPSIS         top

       term

DESCRIPTION         top

   STORAGE LOCATION
       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.

   LEGACY STORAGE FORMAT
       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
            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 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 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 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 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 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.

   EXTENDED NUMBER FORMAT
       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

   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 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 capabilities.

   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,
                   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                       ........ .

LIMITS         top

       Some limitations:

       •   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 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 about the project can be found at 
       ⟨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 2021-06-20.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2021-05-23.)  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

                                                                 term(5)

Pages that refer to this page: tput(1)terminfo(5)term(7)