#    ^ 行首定位
[root@localhost ~]# grep root  /etc/passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
[root@localhost ~]# grep ^root /etc/passwd
root:x:0:0:root:/root:/bin/bash

#    $ 行尾定位
[root@localhost ~]# grep love$ 1.txt 
love

#    . 匹配任意單個(gè)字符
[root@localhost ~]# grep a.c 1.txt 
abc
adc

#    * 匹配前導(dǎo)符0次到多次
[root@localhost ~]# grep "abcde*" 1.txt 
abcd
abcde
abcdef
abcdefj

#    .* 任意多個(gè)字符
[root@localhost ~]# grep ".*" 1.txt 
qian
yoa
huang
kai
kong

#    [] 匹配指定范圍內(nèi)的一個(gè)字符
[root@localhost ~]# grep "[lL]ove" 1.txt 
love
love
Love

#    [-] 匹配指定范圍內(nèi)的一個(gè)字符，連續(xù)的范圍
		[root@localhost ~]# grep "[a-z]ove" 1.txt 
love
love

#    [^] 匹配不在指定組內(nèi)的字符
[root@localhost ~]# grep "[^lL]ove" 1.txt 
1ove
|ove

#    \ 用來轉(zhuǎn)義元字符('' "" \),脫意符
[root@localhost ~]# grep "l\.ve" 1.txt 
l.ve

#    \< 詞首定位符
[root@localhost ~]# grep "\<love" 1.txt 
love
love

#    \> 詞尾定位符
		[root@localhost ~]# grep "love\>" 1.txt 
love
love

#    () 匹配稍后使用的字符的標(biāo)簽
:1,2 s/(.*\)/#\1/      #加注釋

#    x\{m\} 字符x重復(fù)出現(xiàn)m次
[root@localhost ~]# grep "o\{3\}" 1.txt 
|oooove

#    x\{m,\} 字符x重復(fù)出現(xiàn)m次以上
[root@localhost ~]# grep "o\{3,\}" 1.txt 
|oooove
looove
loooooooove

#    x\{m,n\} 字符x重復(fù)出現(xiàn)m到n次
[root@localhost ~]# grep "o\{3,4\}" 1.txt 
|oooove
looove
loooooooove

#    + 匹配1-n個(gè)前導(dǎo)字符
[root@localhost ~]# egrep lo+ve 1.txt 
love
love
looove
loooooooove

#    ？ 匹配0-1個(gè)前導(dǎo)字符
[root@localhost ~]# egrep lo?ve 1.txt 
love
love

#    a | b 匹配a或b
[root@localhost ~]# egrep "o|v" 1.txt 
yoa
kong
duo
gou
love
love

#    () 組字符
[root@localhost ~]# egrep "love(able|rs)" 1.txt 
loveable
lovers

[root@localhost ~]# egrep "loveable|rs" 1.txt 
loveable
lovers