ultrix man page for file

file(1) 						      General Commands Manual							   file(1)

Name
       file - determine file type

Syntax
       file [ -c ] [ -f ffile] [ -m mfile] filename ...

Description
       The  command  performs  a  series of tests on each filename argument in an attempt to classify it.  If an argument appears to be ASCII, the
       command examines the first 1024 bytes and tries to guess its language.

       For character special files, part of this classification is information about which devices the system shows  as  active.   In  particular,
       device-specific	information such as controller type and unit, device type and unit, and status (offline, write locked, density, errors) is
       returned. The general categories currently implemented are disk, tape, and terminal devices. The supported terminal devices  include  Local
       Area Terminals (LAT) but not Local Area Network (LAN) pseudo-terminals.

       The  command  uses  the	file to identify files that have some sort of magic number.  A magic number is any numeric or string constant that
       identifies the file containing the constant.  Commentary at the beginning of explains its format.

Options
       -c   Checks the magic file for format errors by printing the internal representation of the magic file.	No file typing is done under -c.

       -f   Interprets the following argument to be a file containing the names of the files to be examined.

       -m   Instructs file to use an alternate magic file.

Restrictions
       It often does a poor job of distinguishing C programs, shell scripts, English text, and ASCII text.

       It does not recognize many programming languages, including Modula, Pascal, and Lisp.

Files
       /usr/lib/file/magic

See Also
       magic(5)

																	   file(1)