正则表达式实战举例(续):      

    3).*:任意字符

[root@test2 tmp]# cat test2.txt 

lovely

livl

levllaeq

lcveroop

woeijfdklkiod

love mo forerver

hahahh lilylilei

ku hou haha   xixi

zxysypr

love mo forervez

[root@test2 tmp]# grep ".*" test2.txt 

lovely

livl

levllaeq

lcveroop

woeijfdklkiod

love mo forerver

hahahh lilylilei

ku hou haha   xixi

zxysypr

love mo forervez

    

    4)[ ]:匹配一组字符中的任意一个  

[0-9]

[a-z]

[A-Z]

[a-Z]

[a-Z0-9]

[^0-9]

[^a-Z]

[^...]


 [root@test2 tmp]# grep "[a-z][a-z][a-z][A-Z]" passwd --color

rooT:x:0:0:root:/root:/bin/bash



 [root@test2 tmp]# grep "^[a-z][a-z][a-z]:" passwd --color 

bin:x:1:1:bin:/bin:/sbin/nologin

adm:x:3:4:adm:/var/adm:/sbin/nologin

ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin

rpc:x:32:32:Rpcbind Daemon:/var/cache/rpcbind:/sbin/nologin

ntp:x:38:38::/etc/ntp:/sbin/nologin

    5)\ :转义字符,屏蔽元字符的含义。

[root@test2 tmp]# cat 2.txt 

abc

acd

djjoediofjf

diijew9f9e90

a.c

[root@test2 tmp]# grep "a.c" 2.txt 

abc

a.c

[root@test2 tmp]# grep "a\.c" 2.txt 

a.c

未完待续。。。。。。