# File lib/macaddr.rb, line 54
    def address
      return @mac_address if defined? @mac_address and @mac_address
      re = %r/[^:\-](?:[0-9A-F][0-9A-F][:\-]){5}[0-9A-F][0-9A-F][^:\-]/io
      cmds = '/sbin/ifconfig', '/bin/ifconfig', 'ifconfig', 'ipconfig /all'

      null = test(?e, '/dev/null') ? '/dev/null' : 'NUL'

      output = nil
      cmds.each do |cmd|
        status, stdout, stderr = systemu(cmd) rescue next
        next unless stdout and stdout.size > 0
        output = stdout and break
      end
      raise "all of #{ cmds.join ' ' } failed" unless output

      @mac_address = parse(output)
    end