獲取指定頁面中的圖片地址： curl news.baidu.com | grep -Eio '(http|ftp|https)://[A-Za-z0-9_./]+(.jpg|.png|.gif)'
<a >http://news.baidu.com/iphone/img/loading_3.gif</a>
<a >http://h.hiphotos.baidu.com/news/pic/item/5d6034a85edf8db1cab9d24a0b23dd54564e740c.jpg</a>
<a >http://a.hiphotos.baidu.com/news/pic/item/a2cc7cd98d1001e9e447bd21ba0e7bec54e797a1.jpg</a>
<a >http://b.hiphotos.baidu.com/news/pic/item/2f738bd4b31c8701d4b01bc8257f9e2f0708ff9e.jpg</a>
<a >http://g.hiphotos.baidu.com/news/pic/item/2e2eb9389b504fc23d951e2be7dde71191ef6dd2.jpg</a>
......
<a >http://news.baidu.com/resource/img/tuiguang/news_ad_header_ipad.png</a>
<a >http://news.baidu.com/resource/img/tuiguang/news_home_ad_dialog_ipad_news.png</a>
<a >http://news.baidu.com/resource/img/tuiguang/news_home_ad_dialog_ipad_news.png</a>
