# term 5

    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/share/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: /usr/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/share/terminfo/a/act4.   Syn-
                onyms  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:  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*sec-
           ond+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, 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.

           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 begin-
           ning 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.

### 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 (0542)

           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

           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 has been recompiled (result-
           ing  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 bool-
           ean, number, and string capabilities.

           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.

           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.

           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.

## 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
           extended number support for ncurses 6.1

           Eric S. Raymond
           documented legacy terminfo format, e.g., from pcurses.

                                                                           term(5)