正则

原创

ruochen

发布于 2021-11-26 13:08:06

3.1K0

2.1正则表达式概述

1.目标：

    *方便人们处理文本，字符的内容

    *方便人们处理有规律的内容

    *方便人们使用三剑客，高级语言处理字符

2.应用场景：

  通过特殊符号"^ $   .*.*    ()   []    [^]    |  +  ..."，表达或匹配有规律的内容

3.举例

   匹配手机号

   匹配身份证号

2.2正则分类

re (regular expression)

基础正则 bre

扩展正则 ere

1.基础正则符号： ^  $  .  *   .*     ^$  []    [^]

2.扩展正则： +    |   ()    {}   ?

2.3区别

image.png

2.4正则误区

（1）正则vs通配符

image.png

（2）通配符快速复习指南

#匹配文件名字

## * 所有

ls *.txt

find /    -type f  -name "*.avi"

## {} 生成序列

###

echo {a..z}   {A..Z}

echo {0..10}

echo {01..100}

### 无规律

[root@m01 ~]# echo {a,b,z}

a b z

[root@m01 ~]# cp   oldboy.txt{,.bak}

[root@m01 ~]# ll oldboy.txt*

-rwxrwxrwx. 1 root root 23 Apr 25 16:41 oldboy.txt

-rwxr-xr-x  1 root root 23 Jul  1 09:11 oldboy.txt.bak

[root@m01 ~]# echo cp   oldboy.txt{,.bak}

cp oldboy.txt oldboy.txt.bak

[root@m01 ~]#

[root@m01 ~]# echo cp   A{,.bak}

cp A A.bak

[root@m01 ~]# echo cp   A{,C}

cp A AC

[root@m01 ~]#

### 进阶

[root@m01 ~]# echo {1..10..2}

1 3 5 7 9

[root@m01 ~]# echo {2..10..2}

2 4 6 8 10

[root@m01 ~]# echo {a..z..2}

a c e g i k m o q s u w y

[root@m01 ~]#

[root@m01 ~]#

[root@m01 ~]# seq 1   2 10

### 了解更多 █████████

man bash

2.5基础正则

image.png

（1）^ $

oldboy.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!

image.png

2) ^$ 空行

image.png

[root@m01 /server/files]# grep -v '^$' oldboy.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!

案例排除 /etc/ssh/sshd_config中的空行和注释行

grep -v '^$' /etc/ssh/sshd_config |grep -v '#'

egrep -v '^$|#' /etc/ssh/sshd_config

sed -r '/^$|#/p'   /etc/ssh/sshd_config

awk   '/^$|#/'   /etc/ssh/sshd_config

其他方法:

grep '^[a-zA-Z]' /etc/ssh/sshd_config

grep '^[a-Z]' /etc/ssh/sshd_config

3) .

image.png

4) * 前一个字符连续出现0次或0次以上

[root@m01 /server/files]# grep '0*' oldboy.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@m01 /server/files]#

[root@m01 /server/files]#

[root@m01 /server/files]#

[root@m01 /server/files]# #grep '0*' oldboy.txt

[root@m01 /server/files]# # 连续出现的时候 0次以上 0 0000 0000000

[root@m01 /server/files]# # 连续出现的时候 0次     ''

[root@m01 /server/files]# grep '' oldboy.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

挑战: 排除文件中的空行,只包含空格的行

[root@m01 /server/files]# echo -e 'oldboy\n\nlidao   \n     \n\nlidao\n   lidao     '>star.txt

[root@m01 /server/files]# cat star.txt

oldboy

lidao

lidao

   lidao

[root@m01 /server/files]#

[root@m01 /server/files]# cat -A star.txt

oldboy$

lidao    $

lidao$

   lidao     $

#方法1

[root@m01 /server/files]# grep -v '^$' star.txt

oldboy

lidao

lidao

   lidao

[root@m01 /server/files]# grep -v '^$' star.txt |grep -v '^ *$'

oldboy

lidao

lidao

   lidao

#方法2

[root@m01 /server/files]# grep -v '^ *$' star.txt

oldboy

lidao

lidao

   lidao

[root@m01 /server/files]# #^ *$   *0次以上   ^ $ ^ $ ^         $

[root@m01 /server/files]# #^ *$   *0次       ^$

[root@m01 /server/files]# grep -v '^ *$' star.txt

oldboy

lidao

lidao

   lidao

#方法3

[root@m01 /server/files]# egrep -v '^$|^ +$' star.txt

oldboy

lidao

lidao

   lidao

5) .* 所有

# 正则表达式的贪婪性   .* 匹配所有   连续出现 * + {} ?

grep  '^.*:' passwd

# 限制方法-增加条件/内容

image.png

正则表达式表示并且

#匹配 oldboy.txt中 以字母m开头并且以m空格即为的行

[root@m01 /server/files]# grep '^m.*m $' oldboy.txt

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

[root@m01 /server/files]#

[root@m01 /server/files]#

[root@m01 /server/files]# grep '^m' oldboy.txt

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

my qq is 49000448

my god ,i am not oldbey,but OLDBOY!

[root@m01 /server/files]# grep '^m' oldboy.txt |grep 'm $'

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

6) 一个整体匹配任意一个字符a或b或c

#匹配数字

[0-9]

#匹配字母(大小写字母)

[a-z]

[A-Z]

[a-zA-Z]

[a-Z]

# 基础使用

[root@m01 /server/files]# grep '[abc]' oldboy.txt

[root@m01 /server/files]# grep -o '[abc]' oldboy.txt

[root@m01 /server/files]# grep -o '[abc][abc]' oldboy.txt

ac

ac

ba

ba

ba

[root@m01 /server/files]# grep '[abc][abc]' oldboy.txt

[root@m01 /server/files]# grep '[abc][abc]' oldboy.txt

I am oldboy teacher!

I teach linux.

I like badminton ball ,billiard ball and chinese chess

补充: \ 转义字符脱掉马甲打回原形

[root@m01 /server/files]# grep '\.$' oldboy.txt

I teach linux.

not 4900000448.

[root@m01 /server/files]# # \ 转义字符 脱掉马甲打回原形 去掉特殊含义

[root@m01 /server/files]#

[root@m01 /server/files]# grep '[.^$!!??]$' oldboy.txt

I am oldboy teacher!

I teach linux.

I like badminton ball ,billiard ball and chinese chess!

not 4900000448.

[root@m01 /server/files]#

[root@m01 /server/files]# vim oldboy.txt

[root@m01 /server/files]#

[root@m01 /server/files]# grep '[.^$!!??]$' oldboy.txt

I am oldboy teacher!

I teach linux.

I like badminton ball ,billiard ball and chinese chess!

not 4900000448.

^^^^$$$$$....****?????!!!!

$$..**?????!!!!

^^^^$$..**???!!!!

[root@m01 /server/files]# grep '[.^$!!??]' oldboy.txt

[root@m01 /server/files]# grep '[.^$!!??]' oldboy.txt

I am oldboy teacher!

I teach linux.

7) ^ 一个整体匹配排除a或排除b或排除c的内容

image.png

进阶: 匹配出/etc/passwd的第1列

grep '^[a-zA-Z0-9]*' /etc/passwd

useradd quede_user_name666

grep '^[a-zA-Z0-9]*' /etc/passwd

grep '^[a-zA-Z0-9_]*' /etc/passwd

useradd quede_user_name666-01

grep '^[a-zA-Z0-9_]*' /etc/passwd

grep '^[a-zA-Z0-9_-]*' /etc/passwd

useradd quede_user_name666-01...

grep '^[a-zA-Z0-9_-]*' /etc/passwd

#需要慢慢理解

[root@m01 /server/files]# grep '^[^:]*' /etc/passwd

egrep '^[^:]+' /etc/passwd

8) BRE 小结

image.png

2.6 扩展正则

image.png

1) |

[root@m01 /server/files]# egrep 'oldboy|my' oldboy.txt

I am oldboy teacher!

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

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

my qq is 49000448

my god ,i am not oldbey,but OLDBOY!

[root@m01 /server/files]# grep -E 'oldboy|my' oldboy.txt

[root@m01 /server/files]# grep -E 'oldboy|my' oldboy.txt

I am oldboy teacher!

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

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

my qq is 49000448

my god ,i am not oldbey,but OLDBOY!

[root@m01 /server/files]#

[root@m01 /server/files]# grep   'oldboy\|my' oldboy.txt

I am oldboy teacher!

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

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

my qq is 49000448

my god ,i am not oldbey,but OLDBOY!

[root@m01 /server/files]# egrep 'oldbo|ey' oldboy.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@m01 /server/files]# egrep 'oldb(o|e)y' oldboy.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@m01 /server/files]# egrep 'oldb[oe]y' oldboy.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

[] |

image.png

2) + 前一个字符连续出1次或1次以上

#取出文件中所有的单词 #统计重复次数

egrep -o '[a-Z]+' oldboy.txt

egrep -o '[a-Z]+' oldboy.txt |sort

egrep -o '[a-Z]+' oldboy.txt |sort |uniq -c

egrep -o '[a-Z]+' oldboy.txt |sort |uniq -c |sort -rn

egrep -o '[a-Z]+' oldboy.txt |awk '{word[$1]++}END{for(n in word)print n,word[n]}'

#取出文件中所有的字母 #统计重复次数

egrep -o '[a-Z]' oldboy.txt

egrep -o '[a-Z]' oldboy.txt |sort

egrep -o '[a-Z]' oldboy.txt |sort |uniq -c

egrep -o '[a-Z]' oldboy.txt |sort |uniq -c |sort -rn

egrep -o '[a-Z]' oldboy.txt |awk '{word[$1]++}END{for(n in word)print n,word[n]}'

awk -vRS='[^a-zA-Z]+' -F ''  '{for(i=1;i<=NF;i++)word[$i]++}END{for(n in word)print n,word[n]}' oldboy.txt

3) {} a{n,m} 前一个字符a连续出现至少n次,最多m次

image.png

[root@m01 /server/files]# egrep '0{1,5}' oldboy.txt

my qq is 49000448

not 4900000448.

[root@m01 /server/files]# egrep -o '0{1,5}' oldboy.txt

[root@m01 /server/files]# egrep '0{3,4}' oldboy.txt

my qq is 49000448

not 4900000448.

[root@m01 /server/files]# egrep -o '0{3,4}' oldboy.txt

[root@m01 /server/files]# egrep '0{3}' oldboy.txt

my qq is 49000448

not 4900000448.

[root@m01 /server/files]# egrep '0{2}' oldboy.txt

my qq is 49000448

not 4900000448.

[root@m01 /server/files]# egrep '0{2}' oldboy.txt -o

id.txt

金 211324198705244720

万 500224197105168312

任 1231231231oldboy

任 3oldboy

任 lidao97303136098

任 alex2197303136098

任 350182197303oldgir

吕 211282199209113038

孔 150000198309176071

邹 371001197412221284

贺 130185200011215926

杜 362522198711278101

向 14052219961008852X

取出文件中正确的身份证号码的行

[root@m01 /server/files]# egrep '[0-9]{17}[0-9X]' id.txt

金 211324198705244720

万 500224197105168312

#正则使用流程

##先找出规律

##通过正则匹配

4) ( ) 表示整体后向引用()

[root@m01 /server/files]# xfs_info /dev/sda1 |egrep 'isize|bsize'

meta-data=/dev/sda1              isize=512    agcount=4, agsize=65536 blks

data     =                       bsize=4096   blocks=262144, imaxpct=25

naming   =version 2              bsize=4096   ascii-ci=0 ftype=1

log      =internal               bsize=4096   blocks=2560, version=2

[root@m01 /server/files]# xfs_info /dev/sda1 |egrep 'i|bsize'

meta-data=/dev/sda1              isize=512    agcount=4, agsize=65536 blks

         =                       sectsz=512   attr=2, projid32bit=1

         =                       crc=1        finobt=0 spinodes=0

data     =                       bsize=4096   blocks=262144, imaxpct=25

         =                       sunit=0      swidth=0 blks

naming   =version 2              bsize=4096   ascii-ci=0 ftype=1

log      =internal               bsize=4096   blocks=2560, version=2

         =                       sectsz=512   sunit=0 blks, lazy-count=1

realtime =none                   extsz=4096   blocks=0, rtextents=0

[root@m01 /server/files]# xfs_info /dev/sda1 |egrep '(i|b)size'

[root@m01 /server/files]# xfs_info /dev/sda1 |egrep '(i|b)size'

meta-data=/dev/sda1              isize=512    agcount=4, agsize=65536 blks

data     =                       bsize=4096   blocks=262144, imaxpct=25

naming   =version 2              bsize=4096   ascii-ci=0 ftype=1

log      =internal               bsize=4096   blocks=2560, version=2

## 后项引用中的 ()

[root@m01 /server/files]# echo 123456

[root@m01 /server/files]# echo '<123456>'

<123456>

[root@m01 /server/files]# echo 123456 |sed -r 's#(.*)#<\1>#g'

<123456>

[root@m01 /server/files]# echo 123456 |sed -r 's#(.)#<\1>#g'

<1><2><3><4><5><6>

[root@m01 /server/files]# echo {1..10}

1 2 3 4 5 6 7 8 9 10

[root@m01 /server/files]# echo {1..10}

1 2 3 4 5 6 7 8 9 10

[root@m01 /server/files]# echo {1..10} |sed -r 's#([0-9])#<\1>#g'

<1> <2> <3> <4> <5> <6> <7> <8> <9> <1><0>

[root@m01 /server/files]# echo {1..10} |sed -r 's#([0-9]+)#<\1>#g'

<1> <2> <3> <4> <5> <6> <7> <8> <9> <10>

[root@m01 /server/files]#

[root@m01 /server/files]#

[root@m01 /server/files]# echo {1..10} |sed -r 's#(4|6|10)#<\1>#g'

1 2 3 <4> 5 <6> 7 8 9 <10>

5) ? 前一个字符出现了0次或1次

[root@m01 /server/files]# cat job.txt

joooooooob

jooooob

jooob

job

jb

[root@m01 /server/files]# egrep 'job|jb' job.txt

job

jb

[root@m01 /server/files]# egrep 'jo?b' job.txt

job

jb

仅仅使用正则取出ip地址

root@m01 /server/files]# ip a s eth0 |egrep -o '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'|head -1

10.0.0.61

[root@m01 /server/files]# ip a s eth0 |egrep '([0-9]{1,3}\.?){4}'

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

   inet 10.0.0.61/24 brd 10.0.0.255 scope global eth0

[root@m01 /server/files]# ip a s eth0 |egrep '([0-9]{1,3}\.?){4}' -o

10.0.0.61

10.0.0.255

[root@m01 /server/files]# ip a s eth0 |egrep '([0-9]{1,3}\.?){4}' -o |sed -n 3p

10.0.0.61

image.png

2.7perl正则

1) 零宽断言

#取出 下面的 uptime时间

16:30:13 up 41 days, 17:41,  1 user, load average: 0.03, 0.09, 0.08

16:29:51 up  7:20,  2 users, load average: 0.01, 0.03, 0.05

16:41:42 up 0 min,  1 user, load average: 0.43, 0.13, 0.05

[root@m01 ~]# grep -Po '(?<=up).*(?=\d+ user)' uptime.txt

41 days, 17:41,

  7:20,

0 min,

23 min,

image.png

2)perl 符号

image.png

2.8其他符号

1) 括号表达式了解

[:alnum:]

[root@m01 /server/files]# grep '[[:alnum:]]' oldboy.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!

____aaaaolidao996

[root@m01 /server/files]# grep '[a-zA-Z0-9]' oldboy.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!

____aaaaolidao996

[root@m01 /server/files]#

[root@m01 /server/files]# grep -P '\w' oldboy.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!

____aaaaolidao996

2) 其他字符

[root@m01 /server/files]# cat name.txt

oldboy

oldboylidao

oldboy666

oldboyedu

[root@m01 /server/files]# grep -w oldboy name.txt

oldboy

[root@m01 /server/files]# grep '\boldboy\b' name.txt

oldboy

[root@m01 /server/files]# grep '\<oldboy\>' name.txt

oldboy

原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。

如有侵权，请联系 cloudcommunity@tencent.com 删除。

ssh

正则表达式

原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。

如有侵权，请联系 cloudcommunity@tencent.com 删除。

ssh

正则表达式

正则

正则

2.1正则表达式概述

2.2正则分类

re (regular expression)

基础正则 bre

扩展正则 ere

2.3区别

2.4正则误区

（1）正则vs通配符

（2）通配符快速复习指南

2.5基础正则

（1）^ $

2) ^$ 空行

案例 排除 /etc/ssh/sshd_config中的空行和注释行

3) .

4) * 前一个字符连续出现0次或0次以上

挑战: 排除文件中的空行,只包含空格的行

5) .* 所有

正则表达式表示 并且

6) 一个整体 匹配任意一个字符a或b或c

补充: \ 转义字符 脱掉马甲打回原形

7) ^ 一个整体 匹配排除a或排除b或排除c的内容

进阶: 匹配出/etc/passwd的第1列

8) BRE 小结

2.6 扩展正则

1) |

[] |

2) + 前一个字符连续出1次或1次以上

3) {} a{n,m} 前一个字符a连续出现至少n次,最多m次

4) ( ) 表示整体 后向引用()

5) ? 前一个字符出现了0次或1次

仅仅使用正则取出ip地址

2.7perl正则

1) 零宽断言

2)perl 符号

2.8其他符号

1) 括号表达式 了解

2) 其他字符

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案例排除 /etc/ssh/sshd_config中的空行和注释行

正则表达式表示并且

6) 一个整体匹配任意一个字符a或b或c

补充: \ 转义字符脱掉马甲打回原形

7) ^ 一个整体匹配排除a或排除b或排除c的内容

4) ( ) 表示整体后向引用()

1) 括号表达式了解