12.27 -第三关练习题之正则练习

Posted 2020-10-19

12.27       

第三关练习题之正则练习

第1章 取出网卡的ip地址（ifconfig）

1.1 定位

[[email protected] oldboy]# ifconfig eth0|sed -n '2p'                       方法一：sed

          inet addr:10.0.0.201  Bcast:10.0.0.255  Mask:255.255.255.0

[[email protected] oldboy]# ifconfig|awk 'NR==2'                            方法二：awk

          inet addr:10.0.0.201  Bcast:10.0.0.255  Mask:255.255.255.0

[[email protected] oldboy]# ifconfig eth0|grep 'cast'                       方法三：grep

          inet addr:10.0.0.201  Bcast:10.0.0.255  Mask:255.255.255.0          找唯一

 

1.2 解决：

1.2.1 方法一：sed |（管道）  把目标前后替换为空(相当于删除)

[[email protected] oldboy]# ifconfig eth0|sed -n '2p'|sed 's#.*r:##g'|sed 's# B.*##g'

10.0.0.201

1.2.2 方法二：sed  ‘|’（或者）

[[email protected] oldboy]# ifconfig eth0|sed -n '2p'|sed -r 's#^.*r:| B.*$##g'

10.0.0.201                                          注意把空格也去掉

1.2.3 方法三：sed（后向引用）

[[email protected] oldboy]# ifconfig eth0|sed -n '2p'|sed -r 's#^.*r:(.*)B.*$#\1#g'

10.0.0.201

终结命令

[[email protected] oldboy]# ifconfig eth0 |sed -rn '2s#^.*r:(.*) Bca.*$#\1#gp'

10.0.0.201

 

1.2.4 方法四：awk -F

[[email protected] oldboy]# ifconfig eth0 |awk 'NR==2'|awk -F "[ :]+" '{print $4}'

10.0.0.201

终结命令

'NR==2{print $4}'

 ‘条件    {命令}’

[[email protected] oldboy]# ifconfig eth0|awk -F "[ :]+" 'NR==2{print $4}'

10.0.0.201

 

1.2.5 方法五grep/egrep

[[email protected] oldboy]# ifconfig eth0|awk 'NR==2'|egrep '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+' -o
10.0.0.200
10.0.0.255
255.255.255.0
[[email protected] oldboy]# ifconfig eth0|awk 'NR==2'|egrep '([0-9]+\.){3}[0-9]+' -o
10.0.0.200
10.0.0.255
255.255.255.0
[[email protected] oldboy]# ifconfig eth0|awk 'NR==2'|egrep '([0-9]+\.?){4}' -o
10.0.0.200
10.0.0.255
255.255.255.0

方法六:cut  1. cut   -d指定分隔符     -f 指定某一列

[[email protected] oldboy]# ifconfig eth0|awk 'NR==2'|cut -d ":" -f2

10.0.0.201  Bcast

[[email protected] oldboy]# ifconfig eth0|awk 'NR==2'|cut -d ":" -f2|cut -d " " -f1

10.0.0.201

2. cut      sed命令把:替换为空格, cut指定空格为分隔符

[[email protected] oldboy]# ifconfig eth0|awk 'NR==2'|sed 's#:# #g'|cut -d " " -f13

10.0.0.201

 

1.3 练习:执行ip a s eth0命令取出ip

[[email protected] ~]# ip a s eth0

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

    link/ether 00:0c:29:9c:08:2c brd ff:ff:ff:ff:ff:ff

    inet 10.0.0.201/24 brd 10.0.0.255 scope global eth0

    inet6 fe80::20c:29ff:fe9c:82c/64 scope link

       valid_lft forever preferred_lft forever

方法一: awk终极版

[[email protected] ~]# ip a s eth0 |awk '/eth0$/'

    inet 10.0.0.201/24 brd 10.0.0.255 scope global eth0

[[email protected] ~]# ip a s eth0 |awk -F "[ /]+" '/eth0$/{print $3}'

10.0.0.201

方法二: awk

[[email protected] oldboy]# ip a s eth0 |awk 'NR==3'|awk -F “[ /]+”   '{print $3}'

10.0.0.200

方法三:sed

[[email protected] oldboy]# ip a s eth0 |awk 'NR==3'|sed -r 's#^.*t (.*)/.*$#\1#g'

10.0.0.200

 

1.4 总结:

1.4.1 理解-F指定分隔符

—F “[  :]+”

先找出[  :]+ 正则匹配到什么内容

egrep ‘[  :]+’

把找出来的内容作为分隔符

1.4.2 理解--连续出现(+)

[[email protected] oldboy]# echo '#####[email protected]@@@@2'

#####[email protected]@@@@2

[[email protected] oldboy]# echo '#####[email protected]@@@@2'|egrep '[#@]'

#####[email protected]@@@@2

[[email protected] oldboy]# echo '#####[email protected]@@@@2'|egrep '[#@]' -o

#

#

#

@

@

@

[[email protected] oldboy]#

[[email protected] oldboy]# echo '#####[email protected]@@@@2'|egrep '[#@]+'

#####[email protected]@@@@2

[[email protected] oldboy]# echo '#####[email protected]@@@@2'|egrep '[#@]+' -o

#####

@@@@@

[[email protected] oldboy]# echo '#####[email protected]@@@@2'|awk -F "[#@]+"  '{print $2}'

1

第2章 过滤出oldboy 和31333741

方法一:

[[email protected] ~]# echo "I am oldboy,myqq is 31333741"|awk -F "[ ,]" '{print $3,$6}'

oldboy 31333741

方法二:

[[email protected] ~]# echo "I am oldboy,myqq is 31333741"|sed -r 's#.*m (.*),.*s (.*)#\1 \2#g'

oldboy 31333741

 

 

 

第3章 取出/etc/hosts 文件权限

[[email protected] oldboy]# stat /etc/hosts

  File: `/etc/hosts'

  Size: 177        Blocks: 8          IO Block: 4096   regular file

Device: 803h/2051d Inode: 260127      Links: 2

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

Access: 2017-12-21 23:29:37.849768706 +0800

Modify: 2017-05-20 18:18:04.258143406 +0800

方法一:sed

[[email protected] oldboy]# stat /etc/hosts|sed -n '4p'|sed -r 's#^.*\((.*)/-.*$#\1#g'

0644

方法二:sed终极版

[[email protected] oldboy]# stat /etc/hosts|sed -rn '4s#^.*\((.*)/-.*$#\1#gp'

0644

方法三:awk

[[email protected] oldboy]# stat /etc/hosts|awk -F "[(/]" 'NR==4{print $2}'

0644

方法四:命令本身选项

[[email protected] oldboy]# stat -c%a /etc/hosts

644

第4章 已知/oldboy/test.txt 文件内容为：

oldboy

 

xizi

 

xiaochao

请问如何把文件中的空格过滤掉（要求命令行实现）  ^$   .    [a-z]

方法一:

[[email protected]]# grep -v '^$' test.txt

oldboy

xizi

xiaochao

方法二:

grep  ‘.’test.txt

方法三:

[[email protected] oldboy]# grep '^[a-zA-Z]' test.txt

oldboy

xizi

xiaochao

方法四: awk   !  取反

 awk '!/^$/' test.txt

方法五: sed  d     删除

sed '/^$/d' test.txt

方法六:

[[email protected] oldboy]# sed -rn '/[a-z]/p'  test.txt

ldboy

xizi

xiaochao

方法七:

[[email protected] oldboy]# awk  '/[a-z]/'  test.txt

ldboy

xizi

xiaochao

方法八:

[[email protected] oldboy]# sed -n '/./p' test.txt

ldboy

xizi

xiaochao

方法九:

[[email protected] oldboy]# sed -n '/./p' test.txt

ldboy

xizi

xiaochao

 

4.1 总结:

grep  过滤  找东西

sed   过滤  取行   替换    修改文件内容

awk  过滤   取列   计算统计

 

第5章 已知/oldboy/ett.txt 文件内容为：

oldboy

olldboooy

test

请使用 grep 或 egrep 正则匹配的方式过滤出前两行内容

方法一:

[[email protected] oldboy]# grep '^o' ett.txt

oldboy

olldboooy

方法二:

[[email protected] oldboy]# awk '/^o/' ett.txt

oldboy

olldboooy

方法三:

[[email protected] oldboy]# sed -n '/^o/p' ett.txt

oldboy

olldboooy

方法四:

[[email protected] oldboy]# egrep 'ol+dbo+y' ett.txt

oldboy

olldboooy

方法五:

[[email protected] oldboy]# awk '/ol+dbo+y/' ett.txt

oldboy

olldboooy

方法六:

[[email protected] oldboy]# sed -nr '/ol+dbo+y/p' ett.txt

oldboy

olldboooy

方法七:

[[email protected] oldboy]# awk '/^[a-o]/' ett.txt

oldboy

olldboooy

方法八:sed显示某一行用法

[[email protected] oldboy]# sed -n '1,2p' ett.txt

oldboy

olldboooy

方法九:awk显示某一行用法

[[email protected] oldboy]# awk 'NR= =1,NR= =2' ett.txt

oldboy

olldboooy

方法十:sed--排除t开头的行

[[email protected] oldboy]# sed -n  '/^[^t]/p' ett.txt

oldboy

olldboooy

方法十一:find --排除t开头的行

1.[[email protected] oldboy]# grep '^[^t]' ett.txt

oldboy

olldboooy

2.[[email protected] oldboy]# grep -v '^[t]' ett.txt

oldboy

olldboooy

 

 

第6章 扩展：

6.0.1 系统中默认有centos7没有ifconfig命令，需要yum安装

ip  a  s eth0=====ip  address show  eth0     查看ip地址

 

6.0.2 单引号、双引号及不加引号的简单区别

1.单引号 所见即所得

[[email protected] oldboy]# echo '$LANG $(hostname) `pwd` {1..5}'

$LANG $(hostname) `pwd` {1..5}

 

2.双引号 与单引号类似 特殊符号会被解析  ! $() $ ``  

[[email protected] oldboy]# echo "$LANG $(hostname) `pwd` {1..5}"

en_US.UTF-8 oldboyedu43-lnb /oldboy {1..5}

 

3.不加引号 和双引号类似 支持通配符

[[email protected] oldboy]# echo $LANG $(hostname) `pwd` {1..5}

en_US.UTF-8 oldboyedu43-lnb /oldboy 1 2 3 4 5