smart_diff.rb

#!/usr/bin/env ruby
# encoding: utf-8
require 'digest'

source = ARGV[0]
target = ARGV[1]
md5    = Digest::MD5

def parse(source, crypt)
  File.open(source, 'rb').map(&:strip).each_with_object({}) do |line, lines|
    lines[crypt.digest(line)] = line
  end
end

def compare(source, target, crypt)
  src = source.dup
  tgt = File.open(target, 'rb').map(&:strip).each_with_object({}) do |line, lines|
    hash = crypt.digest(line)
    src.delete(hash) || lines[hash] = line
  end
  [src, tgt]
end

src = parse(source, md5)
missing_src, missing_tgt = compare(src, target, md5)

puts "Missing from source: #{source}:"
missing_src.each { |k, v| puts v }

puts "Missing from target: #{target}:"
missing_tgt.each { |k, v| puts v }