grep基础正则表达式字符说明：
（1）^word：匹配以word开头的内容；
（2）word$：匹配以word结尾的内容；
（3）^$：表示空行
范例1：匹配以m 开头
[root@oldboy-6test]# grep "^m" oldboy.log
my blog is http://oldboy.blog.51cto.com
my qq num is 49000448
my god,i am not oldboy,but OLDBOY!
范例2：匹配以m 结尾
[root@oldboy-6test]# grep "m$" oldboy.log
my blog is http://oldboy.blog.51cto.com
[root@oldboy-6test]#
范例3：匹配 空行
[root@oldboy-6test]# grep -n "^$" oldboy.log
3:
8:
[root@oldboy-6test]# cat -n oldboy.log
1 I am oldboy teacher!
2 I teach linux.
3
4 I like badminton ball,billiard ball and chinese chess!
5 my blog is http://oldboy.blog.51cto.com
6 our site is http://www.etiantian.org
7 my qq num is 49000448
8
9 not 4900000448
10 my god,i am not oldboy,but OLDBOY!
[root@oldboy-6test]#
范例4：排除 空行
[root@oldboy-6test]# grep -v "^$" oldboy.log
I am oldboy teacher!
I teach linux.
I like badminton ball,billiard ball and chinese chess!
my blog is http://oldboy.blog.51cto.com
our site is http://www.etiantian.org
my qq num is 49000448
not 4900000448
my god,i am not oldboy,but OLDBOY!
[root@oldboy-6test]# grep -vn "^$" oldboy.log
1:I am oldboy teacher!
2:I teach linux.
4:I like badminton ball,billiard ball and chinese chess!
5:my blog is http://oldboy.blog.51cto.com
6:our site is http://www.etiantian.org
7:my qq num is 49000448
9:not 4900000448
10:my god,i am not oldboy,but OLDBOY!
[root@oldboy-6test]#
