NAME

file − determine the type of a file by examining its contents

SYNOPSIS

file [ −f ffile ] [ −cL ] [ −m mfile ] filename...

DESCRIPTION

file performs a series of tests on each filename in an attempt to determine what it contains.  If the contents of a file appear to be ASCII text, file examines the first 512 bytes and tries to guess its language. 

file uses the file /etc/magic to identify files that have some sort of magic number, that is, any file containing a numeric or string constant that indicates its type.

OPTIONS

−c Check for format errors in the magic number file.  For reasons of efficiency, this validation is not normally carried out.  No file type-checking is done under −c. 

−f ffile
Get a list of filenames to identify from ffile. 

−L If a file is a symbolic link, test the file the link references rather than the link itself. 

−m mfile
Use mfile as the name of an alternate magic number file. 

EXAMPLE

This example illustrates the use of file on all the files in a specific user’s directory:

example% pwd
/usr/blort/misc
example% file  ∗

code: mc68020 demand paged executable

code.c: c program text

counts: ascii text

doc: roff, nroff , or eqn input text

empty.file: empty

libz: archive random library

memos: directory

project: symbolic link to /usr/project

script: executable shell script

titles: ascii text

s5.stuff: cpio archive

example%

ENVIRONMENT

The environment variables LC_CTYPE, LANG, and LC_default control the character classification throughout file.  On entry to file, these environment variables are checked in the following order: LC_CTYPE, LANG, and LC_default.  When a valid value is found, remaining environment variables for character classification are ignored.  For example, a new setting for LANG does not override the current valid character classification rules of LC_CTYPE.  When none of the values is valid, the shell character classification defaults to the POSIX.1 “C” locale. 

FILES

/etc/magic

SEE ALSO

locale(5), magic(5)

BUGS

file often makes mistakes.  In particular, it often suggests that command files are C programs. 

Does not recognize Pascal or LISP. 

Sun Release 4.1  —  Last change: 2 October 1989