如何在 Mac OS 10.9 下關閉內建螢幕, 只顯示在外接螢幕

http://osxdaily.com/2012/06/15/yet-another-way-to-turn-off-internal-lcd-display-of-macbook-pro-with-lid-open/

這篇寫得是行得通的(我測試過了)