wakelan.rb

#!/usr/bin/env ruby

require 'socket'

def getMacBytes str
  hexb = str.split(/:|-/)
  if hexb.length != 6
    $stderr.puts "Invalid MAC address: #{str}"
    exit 1
  end
  hexb.map { |s| s.hex }
end

if ARGV.length < 2
  $stderr.puts "Usage: #{$0} IP-address mac-address"
  exit 1
end

packet = [ 0xff ] * 6 + getMacBytes(ARGV[1]) * 16
UDPSocket.new.send packet.pack("C*"), 0, ARGV[0], 9