[root@b ~]# cat f.txt

inet addr:192.168.0.110 Bcast:192.168.0.255 Mask:255.255.255.0

[root@b ~]# cat f.txt | sed -nr 's/^.*inet addr:(.*) Bcast:.*$/ip:\1/gp'

ip:192.168.0.110

[root@b ~]# cat f.txt | sed -nr 's/^.*inet addr:(.*) Bcast:(.*) Mask:.*$/ip:\1\nBcast:\2/gp'

ip:192.168.0.110

Bcast:192.168.0.255

 

后向引用

[root@b ~]# cat m.txt

123qwe456

[root@b ~]# cat m.txt |sed -r 's/([0-9]{3})([a-z]{3})([0-9]{3})/\3\2\1/g'|tr 'a-z' 'A-Z'

456QWE123

z注释：s/([0-9]{3})([a-z]{3})([0-9]{3})/\3\2\1/g，表示匹配的123 qwe 456 

tr 'a-z' 'A-Z'表示将小写字母a-z替换为大写字母A-Z

 

[root@b ~]# cat m.txt |sed -r 's/([0-9]{3})([a-z]{3})([0-9]{3})/\3\U\2\1/g'

456QWE123

注释：\U表示将其后面的所有小写内容替换为大写字母

 

[root@b ~]# cat m.txt |sed -r 's/([0-9]{3})([a-z]{3})([0-9]{3})/\3\U\2\1/g'|sed -r 's/(.*)([A-Z]{3})(.*)/\3\L\2\1/g'

123qwe456

注释：\L表示将其后面的所有大写内容替换为小写字母

 

[root@b ~]# echo $RANDOM | md5sum |tr '0-9' 'a-z' |cut -c 1-8

fcdfcdfh

注释：输出一个系统随机数，计算md5的hash值，然后替换所有数字为小写字母，通过cut命令提取前8位数字

 

 

[root@b ~]# for i in `seq 1000`;do echo $RANDOM |md5sum|tr '0-9' 'a-z' | cut -c 1-10 >>l.txt;done

注释：使用for循环1000次，执行random系统随机数，并将结果输出到l.txt文件中

[root@b ~]# cat l.txt |sort |uniq -c | sort -nr |awk '$1>1{print $0}'|wc -l

注释：查看l.txt文件，通过sort排序和uniq去重操作后，使用awk命令将重复次数大于1的行打印出来，通过wc -l进行行数统计

 

 

[root@b ~]# echo '123456789' | sed -r 's/./&\n/g'|sed '$d'

1

2

3

4

5

6

7

8

9

注释：输出123456789到管道，通过sed命令过滤，s/./&\n/g表示将任意一个字符替换为在其后面加\n换行符，再通过sed ‘$d’ 命令去除最后一行空行

 

 

 

 

[root@b ~]# cat b.txt

Filesystem Type Size Used Avail Use% Mounted on

/dev/mapper/cl_b-root xfs 36G 12G 25G 32% /

devtmpfs devtmpfs 2.0G 0 2.0G 0% /dev

tmpfs tmpfs 2.1G 0 2.1G 0% /dev/shm

tmpfs tmpfs 2.1G 8.7M 2.0G 1% /run

tmpfs tmpfs 2.1G 0 2.1G 0% /sys/fs/cgroup

/dev/sda1 xfs 297M 122M 176M 41% /boot

/dev/mapper/cl_b-home xfs 2.0G 33M 2.0G 2% /home

/dev/mapper/cl_b-var xfs 4.3G 389M 4.0G 9% /var

tmpfs tmpfs 410M 0 410M 0% /run/user/0

[root@b ~]# cat b.txt |sed '/tmpfs/!d'

devtmpfs devtmpfs 2.0G 0 2.0G 0% /dev

tmpfs tmpfs 2.1G 0 2.1G 0% /dev/shm

tmpfs tmpfs 2.1G 8.7M 2.0G 1% /run

tmpfs tmpfs 2.1G 0 2.1G 0% /sys/fs/cgroup

tmpfs tmpfs 410M 0 410M 0% /run/user/0

注释：sed '/tmpfs/!d'表示匹配tmpfs的行保留，其余内容全部删除。！表示取反的意思

 

 

 

 

[root@b ~]# cat -E m.txt

123qwe456$

　　　　  $

$

$

$

    　　　　　　$

[root@b ~]# cat m.txt | sed -r '/^$/d'　　　　#只删除了空行，无法删除空格行

123qwe456

 

[root@b ~]# cat m.txt | sed -r '/^$|[ \t]+/d'　　#同时删除空行和空格行

123qwe456

[root@b ~]#

 

 

[root@b ~]# cat -n a.txt

1 flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500

2 inet 192.168.0.104 netmask 255.255.255.0 broadcast 192.168.0.255

3 inet6 fe80::ad90:d426:9937:f9cd prefixlen 64 scopeid 0x20<link>

4 ether 00:0c:29:60:68:5a txqueuelen 1000 (Ethernet)

5 RX packets 1948 bytes 207628 (202.7 KiB)

6 RX errors 0 dropped 0 overruns 0 frame 0

7 TX packets 1203 bytes 194327 (189.7 KiB)

8 TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

9

[root@b ~]# cat -n a.txt | sed '5,7s/RX/riririri/g'

1 flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500

2 inet 192.168.0.104 netmask 255.255.255.0 broadcast 192.168.0.255

3 inet6 fe80::ad90:d426:9937:f9cd prefixlen 64 scopeid 0x20<link>

4 ether 00:0c:29:60:68:5a txqueuelen 1000 (Ethernet)

5 riririri packets 1948 bytes 207628 (202.7 KiB)

6 riririri errors 0 dropped 0 overruns 0 frame 0

7 TX packets 1203 bytes 194327 (189.7 KiB)

8 TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

9

注释：sed '5,7s/RX/riririri/g'表示将5-7行的所有RX替换为riririri字符串。

 

[root@b ~]# cat -n a.txt | sed -n '1,3p'　　　　#打印1-3行，共三行

1 flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500

2 inet 192.168.0.104 netmask 255.255.255.0 broadcast 192.168.0.255

3 inet6 fe80::ad90:d426:9937:f9cd prefixlen 64 scopeid 0x20<link>

[root@b ~]# cat -n a.txt | sed -n '1p;3p'　　　#打印1行和3行，共两行　

1 flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500

3 inet6 fe80::ad90:d426:9937:f9cd prefixlen 64 scopeid 0x20<link>

[root@b ~]# cat -n a.txt | sed -n '1,+3p'　　　#打印1行和其后的3行，共四行

1 flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500

2 inet 192.168.0.104 netmask 255.255.255.0 broadcast 192.168.0.255

3 inet6 fe80::ad90:d426:9937:f9cd prefixlen 64 scopeid 0x20<link>

4 ether 00:0c:29:60:68:5a txqueuelen 1000 (Ethernet)

 

sed的多条件过滤语句写法

[root@b ~]# cat f.txt

inet addr:192.168.0.110 Bcast:192.168.0.255 Mask:255.255.255.0

[root@b ~]# cat f.txt |sed -e 's/inet/forward/' -e 's/addr/home/'

forward home:192.168.0.110 Bcast:192.168.0.255 Mask:255.255.255.0

[root@b ~]# cat f.txt |sed 's/inet/forward/;s/addr/home/'

forward home:192.168.0.110 Bcast:192.168.0.255 Mask:255.255.255.0

[root@b ~]# cat f.txt |sed -e '{

s/inet/forward/

s/addr/home/

}'

forward home:192.168.0.110 Bcast:192.168.0.255 Mask:255.255.255.0

 

 

 

 

[root@b ~]# cat f.txt

inet addr:192.168.0.110 Bcast:192.168.0.255 Mask:255.255.255.0

[root@b ~]# cat s.txt

s/inet/forward/

s/addr/home/

[root@b ~]# sed -f s.txt f.txt

forward home:192.168.0.110 Bcast:192.168.0.255 Mask:255.255.255.0

[root@b ~]# sed -r -f s.txt f.txt

forward home:192.168.0.110 Bcast:192.168.0.255 Mask:255.255.255.0

注释：sed 的-f参数，表示过滤的条件都来自于s.txt文件

 

 

 删除c语言的所有注释

删除含有//的注释行

 删除/*……*/的注释行

删除/*  至*/之间的所有内容