defaults write com.apple.Safari CustomUserAgent "'Mozilla/5.0 (iPad; CPU OS 5_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9B176 Safari/7534.48.3'"清除默认项代码
defaults delete com.apple.Safari CustomUserAgent可以屏蔽些FLASH广告，还可以用HTML5来看视频去广告~