# term

## NAME



           term - format of compiled term file.
    


## SYNOPSIS



           **term**
    


## DESCRIPTION



       **STORAGE LOCATION**
           Compiled terminfo descriptions are placed under the directory
           **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: **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 **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:
    
                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
           significant 8 bits of the value, and the second byte contains the
           most significant 8 bits.  (Thus, the value represented is
           256*second+first.)  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.
    
           Numbers in a terminal description, whether they are entries in the
           _numbers_ 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:
    
           •   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).
    
           •   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.
    
           •   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_ section is terminated with an ASCII NUL character.
    
           The _boolean flags_ section has one byte for each flag.  Boolean
           capabilities are either 1 or 0 (true or false) according to
           whether the terminal 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 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)  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:
    
           •   a different magic number (octal 01036)
    
           •   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



       **setupterm**
           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** was 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.
    
       **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
           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.
    
           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(1) 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
           applications.  Portable applications should use the **tigetflag** and
           related functions described in **curs_terminfo**(3X) for reading
           terminal capabilities.
    
       **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 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.
    
           Compiled entries are limited to 32768 bytes because offsets into
           the _strings table_ use two-byte integers.  The legacy format could
           have supported 32768-byte entries, but was limited a virtual
           memory page's 4096 bytes.
    


## FILES



           terminfo/*/*   compiled terminal capability database
    


* * *