from http://osx.miko.org/index.php/Beginning_OS_X_Mavericks/%E3%82%A4%E3%83%B3%E3%83%95%E3%83%A9%E6%95%B4%E5%82%99%E7%B7%A8#.E5.88.A9.E7.94.A8.E8.80.85.E5.8D.98.E4.BD.8D.E3.81.A7.E8.A8.AD.E5.AE.9A.E3.81.99.E3.82.8B.E5.A0.B4.E5.90.88