#!/usr/bin/env ruby

dir = ARGV[0]
a = `find #{dir} -type f`.split "\n"

hashcmd = "sha1sum"

h = {}
a.each { |fn|
  hash = `#{hashcmd} "#{fn}" | cut -d " " -f1`.strip
  if h.has_key? hash
    h[hash] << fn
  else
    h[hash] = [fn]
  end
}

h.each { |k,v|
  v.sort!
  if v.size > 1
    puts k
    v.each { |i| puts "\t#{i}" }
    puts
  end
}