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) command?

This is regarding MIME or content type, not file system classifications, such as directory, file, or socket.

Answer 1

There is a ruby binding to libmagic that does what you need. It is available as a gem named ruby-filemagic:

gem install ruby-filemagic

Require libmagic-dev.

The documentation seems a little thin, but this should get you started:

$ irb 
irb(main):001:0> require 'filemagic' 
=> true
irb(main):002:0> fm = FileMagic.new
=> #<FileMagic:0x7fd4afb0>
irb(main):003:0> fm.file('foo.zip') 
=> "Zip archive data, at least v2.0 to extract"
irb(main):004:0>