--- FileUtils.mkdir_p( dir, *options )
  Options: noop verbose

  ǥ쥯ȥ dir Ȥοƥǥ쥯ȥƺޤ
  㤨

    FileUtils.mkdir_p '/usr/local/lib/ruby'

  ϰʲǥ쥯ȥ(ʤ)ޤ
      * /usr
      * /usr/local
      * /usr/local/bin
      * /usr/local/bin/ruby

