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term 5



term(5)                                                         term(5)




NAME

       term - format of compiled term file.


SYNOPSIS

       term


DESCRIPTION

STORAGE LOCATION

       Compiled terminfo descriptions are placed under the direc-
       tory /usr/share/terminfo.   Two  configurations  are  sup-
       ported (when building the ncurses libraries):

       directory tree
            A  two-level  scheme is used to avoid a linear search
            of a  huge  UNIX  system  directory:  /usr/share/ter-
            minfo/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/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 terminfo  data  in  the  same  format  as
            stored  in  a directory tree with the terminfo's pri-
            mary 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.

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.  The file is  divided  into
       six parts: the header, terminal names, boolean flags, num-
       bers, 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  sec-
            tion;

            (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 hard-
       ware  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  vari-
       ous  names  for the terminal, separated by the `|' charac-
       ter.  The section is terminated with an ASCII NUL  charac-
       ter.

       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 repre-
       sentation.  Padding information $<nn> and parameter infor-
       mation %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.

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 capabili-
       ties  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 capabilties in the same  order
       as the header information.

       The extended string table contains values for string capa-
       bilities.  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.


PORTABILITY

       Note that it is possible for setupterm to expect a differ-
       ent  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 unrecog-
       nized 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  discus-
       sion of terminfo source compatibility issues.


EXAMPLE

       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,
               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,

       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.  The name field cannot exceed 128 bytes.


FILES

       /usr/share/terminfo/*/*  compiled terminal capability data
       base


SEE ALSO

       curses(3x), terminfo(5).


AUTHORS

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

       Eric S. Raymond



                                                                term(5)

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