Ruby script to find duplicate files

find_dupes.rb

#!/usr/bin/ruby -w

require 'find'
require 'md5'

dir = ARGV[0]
dir = "." unless dir

digests = {}
Find.find( dir ) do |f|
    if File.file?( f ) and File.size?( f ) then
        d = MD5.file( f ).hexdigest
        if digests[d] then
            puts "Duplicates: #{digests[d]} and #{f}"
        else
            digests[d] = f
        end
    end
end