resolv.rb

#!/usr/bin/env ruby

require 'resolv'

fail "No input file!" unless File.file? ARGV[0]
  
File.open( ARGV[0] ).each {|domain|
	File.open( "#{ARGV[0]}.ip", 'w') {|outfile|
		outfile.puts Resolv.getaddress( domain.chomp )
	}
}