linux基础学习-10.4-正则表达式练习题

一、基础正则

环境准备

[root@oldboyedu42-lnb oldboy]# cat /oldboy/re.txt
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 size is 
http://blog.oldboyedu.com

my qq is 49000448
not 4900000448.
my god ,i am not oldbey,but OLDBOY!

1、^ ^m 表示以....开头的行

[root@oldboyedu42-lnb oldboy]# grep '^m' re.txt

my blog is http://oldboy.blog.51cto.com

my qq is 49000448

my god ,i am not oldbey,but OLDBOY!

2、 $ m$ 表示以....结尾的行

[root@oldboyedu42-lnb oldboy]# cat -A re.txt

I am oldboy teacher!$

I teach linux.$

I like badminton ball ,billiard ball and chinese chess!$

my blog is http://oldboy.blog.51cto.com $ #注意此处结尾是空格不是m

our size is http://blog.oldboyedu.com $ #注意此处结尾是空格不是m

my qq is 49000448$

not 4900000448.$

my god ,i am not oldbey,but OLDBOY!$

#删除结尾的空格

[root@oldboyedu42-lnb oldboy]# vim re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

#检查是否修改成功

[root@oldboyedu42-lnb oldboy]# cat -A re.txt

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 size is http://blog.oldboyedu.com$

my qq is 49000448$

not 4900000448.$

my god ,i am not oldbey,but OLDBOY!$

[root@oldboyedu42-lnb oldboy]#

[root@oldboyedu42-lnb oldboy]# grep 'm$' re.txt

my blog is http://oldboy.blog.51cto.com

our size is http://blog.oldboyedu.com

cat -A #显示出文件中所有的符号 $这一行的结尾

[root@oldboyedu42-lnb oldboy]# grep ' ' re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

3、 ^$ 空行这一行里面什么都没有

[root@oldboyedu42-lnb oldboy]# grep -n '^$' re.txt

10:

练习题:排查文件中的空行

[root@oldboyedu42-lnb oldboy]# grep -v '^$' re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

4、 . 任意一个字符不会匹配空行

#grep -o '.' re.txt

#-o 显示grep的执行过程，grep每一次找出什么

grep -o '.' re.txt

#-o 显示grep的执行过程，grep每一次找出什么

#-o 的结果中每一行表示 grep每次找出什么

[root@oldboyedu42-lnb oldboy]# grep '0' re.txt

my qq is 49000448

not 4900000448.

[root@oldboyedu42-lnb oldboy]# grep -o '0' re.txt

[root@oldboyedu42-lnb oldboy]# grep '00' re.txt

my qq is 49000448

not 4900000448.

[root@oldboyedu42-lnb oldboy]# grep -o '00' re.txt

说明：如果匹配的内容在一行中有多处，grep会从左到右匹配到最后一个，多多益善

提示：点（.）的特殊含义小结：

1、当前目录

2、使得文件生效相当于source

3、隐藏文件的开头

4、任意一个字符

5、撬棍转义字符去掉符号特殊含义脱掉马甲，打回原形

显示出文件中以.结尾的行？

[root@oldboyedu42-lnb oldboy]# grep '.$' re.txt

I teach linux.

not 4900000448.

撬棍系列转义字符系列

====== 回车

6、 * 前一个字符连续出现0次或0次以上

[root@oldboyedu42-lnb oldboy]# grep '0*' re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

[root@oldboyedu42-lnb oldboy]#

[root@oldboyedu42-lnb oldboy]# grep '0*' re.txt -o

000

00000

#连续出现

#正则表示连续出现的时候，会尽可能的匹配（吃）更多的符号贪婪性

[root@oldboyedu42-lnb oldboy]# #0* 表示0连续出现0次

[root@oldboyedu42-lnb oldboy]# #0* 表示0连续出现1次及1次以上

[root@oldboyedu42-lnb oldboy]# #0

[root@oldboyedu42-lnb oldboy]# #000

[root@oldboyedu42-lnb oldboy]# #0000000

[root@oldboyedu42-lnb oldboy]# #0* 表示0连续出现0次

[root@oldboyedu42-lnb oldboy]# #'0*' 只出现0次的时候 ====== ''

[root@oldboyedu42-lnb oldboy]# #会把整个文件的内容都显示出来

[root@oldboyedu42-lnb oldboy]# grep '' re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

小结正则之*：

1]] 贪婪性

2]] 连续出现

7、 .* 所有任何符号

#在正则中表示连续出现表示所有贪婪性

找出文件中以字母m开头的行并且以m结尾的行

[root@oldboyedu42-lnb oldboy]# grep '^m' re.txt

my blog is http://oldboy.blog.51cto.com

my qq is 49000448

my god ,i am not oldbey,but OLDBOY!

[root@oldboyedu42-lnb oldboy]# grep '^m' re.txt |grep 'm$'

my blog is http://oldboy.blog.51cto.com

[root@oldboyedu42-lnb oldboy]# grep '^m.*m$' re.txt

my blog is http://oldboy.blog.51cto.com

[root@oldboyedu42-lnb oldboy]# grep '^.*m$' re.txt

my blog is http://oldboy.blog.51cto.com

our size is http://blog.oldboyedu.com

[root@oldboyedu42-lnb oldboy]# grep 'm$' re.txt

my blog is http://oldboy.blog.51cto.com

our size is http://blog.oldboyedu.com

[root@oldboyedu-42mvp ~]# grep '.*m' re.txt

8、 [] [abc] 表示一个整体，a或b或c任意一个字符

[root@oldboyedu42-lnb oldboy]# grep '[abc]' re.txt

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 size is http://blog.oldboyedu.com

my god ,i am not oldbey,but OLDBOY!

grep '[abc]' re.txt -o

===>从哪里来，到哪里去用的是-

[root@oldboyedu42-lnb oldboy]# grep '[a-z]' re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

[root@oldboyedu42-lnb oldboy]# grep '[A-Z]' re.txt

I am oldboy teacher!

I teach linux.

I like badminton ball ,billiard ball and chinese chess!

my god ,i am not oldbey,but OLDBOY!

[root@oldboyedu42-lnb oldboy]# grep '[a-zA-Z]' re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

#找出文件中以m或n开头的行

[root@oldboyedu42-lnb oldboy]# #第1个里程碑-m或n

[root@oldboyedu42-lnb oldboy]# grep '[mn]' re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

[root@oldboyedu42-lnb oldboy]# #第2个里程碑-以m或n开头的行

[root@oldboyedu42-lnb oldboy]# grep '^[mn]' re.txt

my blog is http://oldboy.blog.51cto.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

grep '[a-z]' re.txt

grep '[A-Z]' re.txt

grep '[0-9]' re.txt

9、 [^] 排除 [^abc]

[root@oldboyedu42-lnb ~]# grep '[^abc]' /oldboy/re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

||||||||||||||||||000000000

二、扩展正则

1、 + 前一个字符连续出现1次或多次

[root@oldboyedu42-lnb oldboy]# egrep '0+' re.txt

my qq is 49000448

not 4900000448.

[root@oldboyedu42-lnb oldboy]# egrep '0' re.txt

my qq is 49000448

not 4900000448.

[root@oldboyedu42-lnb oldboy]# egrep '0+' re.txt -o

000

00000

#+可以把连续的字符变为一个整体

[root@oldboyedu42-lnb oldboy]# egrep '0' re.txt -o

[root@oldboyedu42-lnb oldboy]# #连续出现

取出文件中连续出现的小写字母

[root@oldboyedu42-lnb oldboy]# #取出文件中连续出现的小写字母

[root@oldboyedu42-lnb oldboy]# egrep '小写字母+' re.txt

[root@oldboyedu42-lnb oldboy]# egrep '[a-z]+' re.txt

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 size is http://blog.oldboyedu.com

my qq is 49000448

not 4900000448.

my god ,i am not oldbey,but OLDBOY!

[root@oldboyedu42-lnb oldboy]# egrep '[a-z]+' re.txt -o

oldboy

teacher

teach

linux

badminton

ball

billiard

ball

and

chinese

chess

blog

http

oldboy

blog

cto

com

our

size

http

blog

oldboyedu

com

not

god

not

oldbey

but

小结:

1.+连续出现 1次及多次

可以把连续的字符变为一个整体，一次取出来(-o)
+一般与[]配合

#1.找出规律

#2.中英文符号

#3.区分大小写

[root@oldboyedu42-lnb oldboy]# egrep '^[0-9]+$' id.txt

440304199604012792

130528197108126121

342923198310042132

330900199806382320

654126197703092303

131127197105115662

[root@oldboyedu42-lnb oldboy]# egrep '^[0-9]+X$' id.txt

61242619860416291X

[root@oldboyedu42-lnb oldboy]# egrep '^[0-9]+[0-9X]$' id.txt

440304199604012792

130528197108126121

342923198310042132

61242619860416291X

330900199806382320

654126197703092303

131127197105115662

2、 | 或者

[root@oldboyedu42-lnb oldboy]# egrep 'linux或oldboy' re.txt

[root@oldboyedu42-lnb oldboy]# egrep 'linux|oldboy' re.txt

I am oldboy teacher!

I teach linux.

my blog is http://oldboy.blog.51cto.com

our size is http://blog.oldboyedu.com

3、 () 变成一个整体反向引用后向引用

#先乘除后加减，有括号的先算括号里面的

[root@oldboyedu42-lnb oldboy]# egrep 'oldbo|ey' re.txt

I am oldboy teacher!

my blog is http://oldboy.blog.51cto.com

our size is http://blog.oldboyedu.com

my god ,i am not oldbey,but OLDBOY!

[root@oldboyedu42-lnb oldboy]# egrep 'oldb(o|e)y' re.txt

I am oldboy teacher!

my blog is http://oldboy.blog.51cto.com

our size is http://blog.oldboyedu.com

my god ,i am not oldbey,but OLDBOY!

#反向引用后向引用 sed

##先通过()把你想要的内容保护起来，然后再使用

echo 123456|xxxxxxx

<123456>

[root@oldboyedu42-lnb oldboy]# echo 123456

123456

[root@oldboyedu42-lnb oldboy]# echo 123456|sed -r 's#(.*)#1#g'

123456

[root@oldboyedu42-lnb oldboy]# echo 123456|sed -r 's#(.*)#<1>#g'

<123456>

echo 123456

[root@oldboyedu42-lnb oldboy]# echo 123456

123456

[root@oldboyedu42-lnb oldboy]# echo 123456|sed -r 's#12(34)56#1#g'

[root@oldboyedu42-lnb oldboy]# echo 123456|sed -r 's#(1)2(34)5(6)#2#g'

[root@oldboyedu42-lnb oldboy]# echo 123456|sed -r 's#(.).(..)..#2#g'

小结:

1.()小括号 []中括号 {}大括号花括号

2.后向引用（sed）

4、 {} 花括号

0{n,m} 前一个字符连续出现至少n次，最多m次 >=n && <=m

0{n} 前一个字符连续出现n次 ==n

0{n,} 前一个字符连续出现至少n次 >=n

0{,m} 前一个字符连续出现最多m次 <=m

[root@oldboyedu42-lnb oldboy]# egrep '0{1,4}' re.txt

my qq is 49000448

not 4900000448.

[root@oldboyedu42-lnb oldboy]# egrep '0{1,4}' re.txt -o

000

0000

[root@oldboyedu42-lnb oldboy]# egrep '0{2,4}' re.txt

my qq is 49000448

not 4900000448.

[root@oldboyedu42-lnb oldboy]# egrep '0{2,4}' re.txt -o

000

0000

#取出文件中连续出现8次到10次的数字

[root@oldboyedu42-lnb oldboy]# #取出文件中连续出现8次到10次的数字

[root@oldboyedu42-lnb oldboy]# egrep '[0-9]{8,10}' re.txt

my qq is 49000448

not 4900000448.

[root@oldboyedu42-lnb oldboy]# egrep '^[0-9]{17}[0-9X]$' id.txt

440304199604012792

130528197108126121

342923198310042132

61242619860416291X

330900199806382320

654126197703092303

三、取出ip地址(ifconfig ip）

方法1-sed

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|sed -n '2p'

      inet addr:10.0.0.200  Bcast:10.0.0.255  Mask:255.255.255.0

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|sed -n '2p'|sed 's#^.*:##g'

255.255.255.0

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|sed -n '2p'|sed 's#^.*addr:##g'

10.0.0.200 Bcast:10.0.0.255 Mask:255.255.255.0

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|sed -n '2p'|sed 's#^.*addr:##g'|sed 's# Bc.*$##g'

10.0.0.200

#方法2-sed-后向引用

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|sed -n '2p'

      inet addr:10.0.0.200  Bcast:10.0.0.255  Mask:255.255.255.0

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|sed -n '2p'|sed -r 's#^.*dr:(.*) Bc.*$#1#g'

10.0.0.200

#方法3-awk-指定多个分隔符

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|awk 'NR==2'

      inet addr:10.0.0.200  Bcast:10.0.0.255  Mask:255.255.255.0

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|awk 'NR==2'|awk -F "[ :]+" '{print $4}'

10.0.0.200

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|awk 'NR==2'|egrep '[ :]'

      inet addr:10.0.0.200  Bcast:10.0.0.255  Mask:255.255.255.0

[root@oldboyedu42-lnb oldboy]# ifconfig eth0|awk 'NR==2'|egrep '[ :]+'

      inet addr:10.0.0.200  Bcast:10.0.0.255  Mask:255.255.255.0

#方法4-awk-'条件{命令}'

[root@oldboyedu42-lnb ~]# ifconfig eth0|awk 'NR==2'

      inet addr:10.0.0.200  Bcast:10.0.0.255  Mask:255.255.255.0

[root@oldboyedu42-lnb ~]# ifconfig eth0|awk 'NR==2'|awk '{print $2}'

addr:10.0.0.200

[root@oldboyedu42-lnb ~]# #awk '找谁{干啥}'

[root@oldboyedu42-lnb ~]# #awk '条件{命令}'

[root@oldboyedu42-lnb ~]# ifconfig eth0|awk 'NR==2{print $2}'

addr:10.0.0.200

[root@oldboyedu42-lnb ~]# #错误 ifconfig eth0|awk -F"[ :]+" 'NR==2{print $2}'

[root@oldboyedu42-lnb ~]# ifconfig eth0|awk -F "[ :]+" 'NR==2{print $4}'

10.0.0.200

#方法5-sed

sed -nr '2s#^.*dr:(.*) Bc.*$#1#gp'

sed -n '2s#inet#oldboy#gp'

[root@oldboyedu42-lnb ~]# ifconfig eth0|sed -n '2s#inet#oldboy#gp'

      oldboy addr:10.0.0.200  Bcast:10.0.0.255  Mask:255.255.255.0

老男孩IT教育出品-sed命令反向引用取出网卡ip地址详解

https://www.processon.com/view/link/59fa9baae4b0f84f8975eefe

#方法6

[root@oldboyedu42-lnb ~]# ip a s eth0 |awk 'NR==3'

inet 10.0.0.200/24 brd 10.0.0.255 scope global eth0

[root@oldboyedu42-lnb ~]# ip a s eth0 |awk 'NR==3'|awk -F"[ /]+" '{print $3}'

10.0.0.200

#方法7

[root@oldboyedu42-lnb ~]# ip a s eth0 |sed -n '3p'

inet 10.0.0.200/24 brd 10.0.0.255 scope global eth0

[root@oldboyedu42-lnb ~]# ip a s eth0 |sed -n '3p'|sed -r 's#^.* (.*)/##g'

24 brd 10.0.0.255 scope global eth0

[root@oldboyedu42-lnb ~]# ip a s eth0 |sed -n '3p'|sed -r 's#^.* ([0-9.]+)/.*$#1#g'

10.0.0.200

四、取出文件权限

#方法1

[root@oldboyedu42-lnb ~]# stat /etc/hosts |awk -F "[(/]" 'NR==4'

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

[root@oldboyedu42-lnb ~]# stat /etc/hosts |awk -F "[(/]" 'NR==4{print $2}'

0644

#方法2-sed

[root@oldboyedu42-lnb ~]# stat /etc/hosts |sed -n '4p'

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

[root@oldboyedu42-lnb ~]# stat /etc/hosts |sed -n '4p'|sed -r 's#^.*(0.*/##g'

root)

[root@oldboyedu42-lnb ~]# stat /etc/hosts |sed -n '4p'|sed -r 's#^.*(0(.*)/-##g'

rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

[root@oldboyedu42-lnb ~]# stat /etc/hosts |sed -n '4p'|sed -r 's#^.*(0(.*)/-.*$##g'

[root@oldboyedu42-lnb ~]# stat /etc/hosts |sed -n '4p'|sed -r 's#^.*(0(.*)/-.*$#1#g'

644

https://www.processon.com/view/link/59fbc9c0e4b0f84f89765231

#方法3

[root@oldboyedu42-lnb ~]# stat /etc/hosts |awk 'NR==4'|sed -r 's#^.*(0|/.*$##g'

644

#方法4-stat

[root@oldboyedu42-lnb ~]# stat -c%a /etc/hosts

644

[root@oldboyedu42-lnb ~]# #命令的结果中有你想要的

练习题：

1、取ip地址

2、取文件权限