1.抓取网页到本地
选择一个网页，比如 http://www.oschina.net/code/snippet_1391852_26067，用wget抓取到本地。
$ wget http://www.oschina.net/code/snippet_1391852_26067
--2016-12-09 9:20:48-- http://www.oschina.net/code/snippet_1391852_26067
Resolving www.oschina.net (www.oschina.net)... 60.174.156.100
Connecting to www.oschina.net (www.oschina.net)|60.174.156.100|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: ‘snippet_1391852_26067’
snippet_1391852_260 [ <=> ] 44.19K --.-KB/s in 0.1s
2016-12-09 9:20:49 (314 KB/s) - ‘snippet_1391852_26067’ saved [45251]
查看：
$ ls
snippet_1391852_26067
已经抓取到本地。
2.在文件中查找某单词
比如查找return：
$ grep -o return snippet_1391852_26067
return
return
return
return
return
return
return
return
return
return
return
return
3.输出文件中某单词个数
比如输出return的个数：
$ grep -c return snippet_1391852_26067
12
完毕。