Provided by: ncurses-bin_6.2+20201114-2build1_amd64 bug

NAME

       term - format of compiled term file.

SYNOPSIS

       term

DESCRIPTION

   STORAGE LOCATION
       Compiled  terminfo  descriptions  are  placed  under  the  directory  /etc/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:
            /etc/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  /etc/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

   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

       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

       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

       /etc/terminfo/*/*   compiled terminal capability data base

SEE ALSO

       ncurses(3NCURSES), 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.

                                                                                          term(5)