term - format of compiled term file.




   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.

   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.  The file is divided into  six  parts:  the  header,
   terminal names, boolean flags, numbers, strings, and 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 names section;

        (3) the number of bytes in the boolean 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.

   Short integers are stored in 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.)   The value -1 is represented by the two bytes 0377,
   0377; other negative values are illegal.  This  value  generally  means
   that  the corresponding capability is missing from this terminal.  Note
   that 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.

   The  terminal  names section comes next.  It contains the first line of
   the terminfo description, listing the various names for  the  terminal,
   separated  by  the  `|'  character.   The section is terminated with an
   ASCII NUL character.

   The boolean flags have one byte for each flag.  This byte is  either  0
   or  1  as  the  flag is present or absent.  The capabilities are in the
   same order as the file <term.h>.

   Between the boolean 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 in to avoid IOT 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 flags section.  Each capability
   takes up two bytes, and is stored as a little-endian short integer.  If
   the value represented is -1, the capability is taken to be missing.

   The  strings  section  is also similar.  Each capability is stored as a
   short integer, in the format above.  A value of -1 means the capability
   is  missing.   Otherwise,  the  value  is  taken  as an offset from the
   beginning of the string table.  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  final  section is the string table.  It contains all the values of
   string capabilities referenced in the string section.  Each  string  is
   null terminated.

   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)  size of the extended string table in bytes.

        (5)  last offset of the extended string table in bytes.

   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.


   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.

   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.


   As an example, here is a hex dump of  the  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,

   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                       ........ .


   Some limitations: total compiled entries cannot exceed 4096 bytes.  The
   name field cannot exceed 128 bytes.


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


   ncurses(3NCURSES), terminfo(5).


   Thomas E. Dickey
   extended terminfo format for ncurses 5.0
   hashed database support for ncurses 5.6

   Eric S. Raymond



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