FileMagic is a Ruby binding to the magic(4) library, which you may
know better as the file(1) command.  The file(1) command identifies
the type of a file using, among other tests, a test for whether the
file begins with a certain magic number.

Author:	Travis Whitton <whitton@atlantic.net>
WWW:	http://grub.ath.cx/filemagic/