LINUX正则表达式

1 正则表达式简述

简述：处理字符串规则的一套方法，可以过滤，替换特定的字符串。

2 正则表达式清单

基础正则
1.^      word  以word开头
2.       word$ 以word结尾
3. .     任意一个字符
4. \     转义字符
5.*     重复0或多次
6.[xo] 中括号里的任意一个字符
7.[^word] 匹配不是^字符的内容
8.\{n,m\} 重复n-m次
    \{n,\} 重复至少n次
    \{n\} 重复n次

扩展正则
+ 重复1个或一个以上
？ 0或一个
|  或
() 用户组字符串

3 案例

[root@docker ~]# echo "word is me"|grep "^word"
word is me
[root@docker ~]# echo "you are word" |grep "word$"
you are word
[root@docker ~]# echo -e "aoe\nawe"|grep "a.e"
aoe
awe
[root@docker ~]# echo -e "a.e\nawe"|grep "a\.e"
a.e
[root@docker ~]# echo -e "xooooo\nx"|grep "xo*"
xooooo
x
[root@docker ~]# echo -e "xo\nee"|grep "[xo]"
xo
[root@docker ~]# echo -e "xo\nee"|grep "[^xo]"
ee
[root@docker ~]# echo -e "xooooo\nx"|grep "xo{1,2}"
[root@docker ~]# echo -e "xooooo\nx"|grep "xo\{1,2\}"
xooooo
[root@docker ~]# echo -e "xooooo\nx"|grep "xo\{2\}"
xooooo
[root@docker ~]# echo -e "xooooo\nx"|grep "xo\{2,\}"
xooooo
[root@docker ~]# echo -e "xooooo\nx"|egrep "xo+"
xooooo
[root@docker ~]# echo -e "xooooo\nx"|egrep "xo?"
xooooo
x
[root@docker ~]# echo -e "we\rng"|grep "we|r"
[root@docker ~]#
[root@docker ~]# echo -e "we\rng"|egrep "we|r"
ng
[root@docker ~]# echo -e "we\rng"|egrep "e|r"
ng
[root@docker ~]# echo -e "we\nrng"|egrep "e|r"
we
rng
[root@docker ~]# echo -e "good\nbad"|egrep "(good|bad)"
good
bad