# 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:

                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 signifi-
           cant 8 bits of the value, and the second byte contains the most signif-
           icant 8 bits.  (Thus, the value represented is 256*second+first.)  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.

           Numbers in a terminal description, whether they are entries in the num-
           bers 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:

           o   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).

           o   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.

           o   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  sec-
           tion is terminated with an ASCII NUL character.

           The boolean flags section has one byte for each flag.  Boolean capabil-
           ities are either 1 or 0 (true or false) according to whether the termi-
           nal 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  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 (octal 01036)

           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

### setupterm

           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.

### 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 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.

           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 applica-
           tions.  Portable applications should  use  the  tigetflag  and  related
           functions described in curs_terminfo(3x) for reading terminal capabili-
           ties.

### 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  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.

           Compiled  entries  are  limited to 32768 bytes because offsets into the
           strings table use two-byte integers.  The legacy format could have sup-
           ported 32768-byte entries, but was limited a virtual memory page's 4096
           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)