# 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)