代码：

File /Users/wgzhao/Sites/blog.wgzhao.com/source/downloads/code/valid_ip.sh could not be found

测试：

#sh valid_ip.sh
4.2.2.2             : good
a.b.c.d             : bad
192.168.1.1         : good
0.0.0.0             : good
255.255.255.255     : good
255.255.255.256     : bad
192.168.0.1         : good
192.168.0           : bad
1234.123.123.123    : bad