From: "Bartosz Dziewoński" <matma.rex@...>
Date: 2011-10-06T01:57:20+09:00
Subject: Re: Best way to compare lines in 2 files

And if the files are quite small and you couldn't care less about
speed as long as it takes less than 5 seconds you could just do:

lines1 = File.readlines 'file1'
lines2 = File.readlines 'file2'

common = lines1 & lines2
second_only = lines2 - lines1

-- Matma Rex