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Updated: Wednesday, February 9, 2022
 
 

term (5)

Name

term - format of compiled term file.

Synopsis

term

Description

term(5)                       File Formats Manual                      term(5)



NAME
       term - format of compiled term file.

SYNOPSIS
       term

DESCRIPTION
   STORAGE LOCATION
       Compiled   terminfo   descriptions   are  placed  under  the  directory
       /usr/gnu/share/terminfo.  Two configurations are supported (when build-
       ing the ncurses libraries):

       directory tree
            A two-level scheme is used to avoid a linear search of a huge UNIX
            system directory: /usr/gnu/share/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/gnu/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 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.

   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  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:

            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 signifi-
       cant 8 bits of the value, and the second byte contains the most signif-
       icant 8 bits.  (Thus, the value represented is 256*second+first.)  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.

       Numbers in a terminal description, whether they are entries in the num-
       bers 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:

       o   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).

       o   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.

       o   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  sec-
       tion is terminated with an ASCII NUL character.

       The boolean flags section has one byte for each flag.  Boolean capabil-
       ities are either 1 or 0 (true or false) according to whether the termi-
       nal 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  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)  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:

       o   a different magic number (octal 01036)

       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.

PORTABILITY
   setupterm
       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 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 pos-
       sibilities - 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 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.

       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 applica-
       tions.  Portable applications should  use  the  tigetflag  and  related
       functions described in curs_terminfo(3X) for reading terminal capabili-
       ties.

   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  charac-
       ter" of the terminal name used as the intermediate level of a directory
       tree in (two-character) hexadecimal form.

EXAMPLE
       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                       ........ .


LIMITS
       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.

       Compiled  entries  are  limited to 32768 bytes because offsets into the
       strings table use two-byte integers.  The legacy format could have sup-
       ported 32768-byte entries, but was limited a virtual memory page's 4096
       bytes.

FILES
       /usr/gnu/share/terminfo/*/*   compiled terminal capability database


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | library/ncurses  |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+

SEE ALSO
       curses(3X), terminfo(5).

AUTHORS
       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.



NOTES
       Source code for open source software components in Oracle  Solaris  can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-
       code-downloads.html.

       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source   was    downloaded    from     https://invisible-mirror.net/ar-
       chives/ncurses/ncurses-6.3.tar.gz.

       Further information about this software can be found on the open source
       community website at https://invisible-island.net/ncurses/.



                                                                       term(5)