bionic (5) term.5.gz

Provided by: ncurses-bin_6.1-1ubuntu1.18.04.1_amd64 bug

NAME

       term - format of compiled term file.

SYNOPSIS

       term

DESCRIPTION

   STORAGE LOCATION
       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.

   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 ordering or sign extension are made.

       The compiled file is created with the tic program, and read by the routine 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*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.

   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 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.

       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  is  introduced
       by making a few changes to the legacy format:

       •   a different magic number (0542)

       •   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 structures 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 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.

       Direct  access  to  the  TERMTYPE  structure  is provided for legacy applications.  Portable applications
       should use the tigetflag and related  functions  described  in  curs_terminfo(3X)  for  reading  terminal
       capabilities.

       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
       character”  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 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,

       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:

       •   total compiled entries cannot exceed 4096 bytes in the legacy format.

       •   total compiled entries cannot exceed 32768 bytes in the extended format.

       •   the name field cannot exceed 128 bytes.

FILES

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

SEE ALSO

       ncurses(3NCURSES), 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)