NAME

file − determine file type

SYNOPSIS

file [ −c ] [ −f ffile ] [ −m mfile ] arg ... 

DESCRIPTION

File performs a series of tests on each argument in an attempt to classify it.  If an argument appears to be ASCII, file examines the first 512 bytes and tries to guess its language.  If an argument is an executable a.out, file will print the version stamp, provided it is greater than 0 (see ld(1)).

If the −f option is given, the next argument is taken to be a file containing the names of the files to be examined. 

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. Commentary at the beginning of /etc/magic explains its format. 

The −m option instructs file to use an alternate magic file. 

The −c flag causes file to check the magic file for format errors.  This validation is not normally carried out for reasons of efficiency.  No file typing is done under −c. 

EXAMPLE

file textfile programfile directory

reports the file names and directory name, and whether the files are English text, nroff input, a C program, or whatever. 

Version 2.1  —  January 02, 1985