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。。。。。。