Determine file type in Ruby

Question

How does one reliably determine a file\'s type? File extension analysis is not acceptable. There must be a rubyesque tool similar to the UNIX file(1) comman

Answer 1

I found shelling out to be the most reliable. For compatibility on both Mac OS X and Ubuntu Linux I used:

file --mime -b myvideo.mp4
video/mp4; charset=binary

Ubuntu also prints video codec information if it can which is pretty cool:

file -b myvideo.mp4
ISO Media, MPEG v4 system, version 2