Detailed sed command

sed command

• The sed command is more powerful than grep, in addition to having a find function, it also has a replace function

• sed command format: sed -n 'n'p filename , the n in single quotes is a number, which means the number of lines;

• sed can achieve most of the functions of grep, but does not display colors

• sed -n is to print the line that meets the conditions, p is the meaning of print

• sed -r misses

• sed -e for multiple commands, and ; effect one line

• sed '/[0-9]'d 2.txt d means to delete lines that do not contain numbers; it is not a real deletion, it is not displayed, which is equivalent to grep -v negation

• sed -n '/root/'Ip "I" is not case sensitive

• sed -i ' [0-9]'d 2.txt -i is to actually delete the lines that do not contain numbers in the document; half are not recommended.

• Regular | means or, and sed twice means

• sed -r 's/([^:]+):(.*):([^:]+)/\3:\2:\1/' 1.txt With : as the delimiter, the first paragraph Replace each other with the last paragraph, \1 represents the first () content, \2 represents the second () content, and \3 represents the third content.

• sed -r 's/(.*)/aaa:&/g' 1.txt

sed instance 1:

• sed -n '5'p test.txt prints line 5
• sed -n '1,5'p test.txt prints lines 1-5
• sed -n '1,$'p test.txt print all the content can be used
• sed -n '/root/'p test.txt Find lines with root characters; characters should be enclosed in //
• sed -n '/^m/'p test.txt find lines starting with m
• sed -n '/\/login$/'p test.txt Find lines ending with /login, note: here you need to remove / before /login.
• sed -n '/r..o/'p test.txt find lines containing r..o
• sed -n 'oo*'p test.txt matches lines with oo*
• sed -e 'root'p -e '/124/'p -n test.txt matches the 'root' line and the line matching '124'

Find the specified line

• sed -n '5'p test.txt prints line 5; 

[root@yong-02 sed]# sed -n '5'p test.txt 
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin

• sed -n '1,5'p test.txt prints lines 1-5;

[root@yong-02 sed]# sed -n '1,5'p test.txt 
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin

• sed -n '1,$'p test.txt can use (1,$) to print all the content. If there is too much content, the whole content will not be displayed. Print 20 - the last line.

[root@yong-02 sed]# sed -n '20,$'p test.txt 
yyl:x:1001:1002::/home/yyl:/bin/bash
user2:x:1009:1009::/home/user2:/bin/bash
user3:x:1010:1010::/home/user3:/bin/bash
user4:x:1011:1011::/home/user4:/bin/bash
user5:x:1012:1012::/home/user5:/bin/bash
user7:x:1014:1014::/home/user7:/bin/bash

Find the line with the specified string

• sed -n '/root/'p test.txt Find lines with the root character; characters are enclosed in //.

[root@yong-02 sed]# sed -n '/root/'p test.txt 
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin

The content of the query can also be regular

• sed -n '/^m/'p test.txt find lines starting with m '/^m/'p

[root@yong-02 sed]# sed -n '/^m/'p test.txt 
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin

• sed -n '/\/login$/'p test.txt Find lines ending with /login; note: You need to remove the / before /login here.

[root@yong-02 sed]# sed -n '/\/login$/'p test.txt 
daemon:x:2:2:daemon:/sbin:/sbin/login
lp:x:4:7:lp:/var/spool/lpd:/sbin/login

• sed -n '/r..o/'p test.txt find lines containing r.od

[root@yong-02 sed]# sed -n '/r..o/'p test.txt
operator:x:11:0:operator:/root:/sbin/nologin
polkitd:x:999:997:User for polkitd:/:/sbin/nologin

•   sed -n 'oo*'p test.txt matches lines with oo*

[root@yong-02 sed]# sed -n '/oo*/'p test.txt |head 
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/login
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/login
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin

• print lines with numbers sed -n '/[0-9]/'p test.txt

[root@yong-02 sed]# sed -n '/[0-9]/'p test.txt |head 
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/login
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/login
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin

• print lines starting with a number sed -n '/^[0-9]/'p test.txt

[root@yong-02 sed]# sed -n '/^[0-9]/'p test.txt
11systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
124

• sed -e can execute multiple commands; sed -e '/root/'p -e '/124/'p -n test.txt 

[root@yong-02 sed]# sed -e '/root/'p -e '/124/'p -n test.txt
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
124

delete some lines

sed instance 2:

• sed '1'd test.txt delete line 1

[root@yong-02 sed]# cat test.txt
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
11systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
addsfgasd
adsf
124
[root@yong-02 sed]# sed '1'd test.txt
bin:x:1:1:bin:/bin:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
11systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
addsfgasd
adsf
124

• sed '1,3'd test.txt delete lines 1-3

[root@yong-02 sed]# cat test.txt
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
11systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
addsfgasd
adsf
124
[root@yong-02 sed]# sed '1,3'd test.txt
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
11systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
addsfgasd
adsf
124

• sed '/mail/'d test.txt delete lines with mail characters

[root@yong-02 sed]# cat test.txt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
addsfgasd
adsf
124
[root@yong-02 sed]# sed '/mail/'d test.txt
addsfgasd
adsf
124

sed replace function

• sed 's/[0-9]/a/g' 1.txt //Replace all numbers with a
• sed 's/root/ROOT/g' 1.txt //Replace all root in file 1.txt with ROOT
• sed '1,10s/root/ROOT/g' 1.txt //Replace root in the first 10 lines of file 1.txt with ROOT
• paste 1.txt 2.txt //Concatenate the content of 1.txt with the content of 2.txt
• sed -i '30,40s/^.*$/#&/g' 1.txt //Add # to comment out
• sed -i 's/^/#/g' 1.txt //Add # to comment out
• s is the meaning of replacement, g is global replacement, otherwise it will be replaced once, / can use #@ to replace the character

sed instance 3:

• sed '1,2s/ot/to/g' test.txt
• sed 's#ot#to#g' test.txt
• sed 's/[0-9]//g' test.txt
• sed 's/[a-zA-Z]//g' test.txt
• sed -r 's/(rot)(.*)(bash)/\3\2\1/' test.txt
• sed 's/^.*$/123&/' test.txt
• sed -i 's/ot/to/g' test.txt

instance analysis

• Replace ot in lines 1 to 2 with to sed '1,2s/ot/to/g' test.txt

[root@yong-02 sed]# sed '1,2s/ot/to/g' test.txt |head -5
roto:x:0:0:roto:/roto:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/login
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/login

• / can be replaced with # or @

[root@yong-02 sed]# sed '1,2s#ot#to#g' test.txt |head -5
roto:x:0:0:roto:/roto:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/login
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/login

• delete all numbers

[root@yong-02 sed]# sed 's/[0-9]//g' test.txt |head -5
root:x:::root:/root:/bin/bash
bin:x:::bin:/bin:/sbin/nologin
daemon:x:::daemon:/sbin:/sbin/login
adm:x:::adm:/var/adm:/sbin/nologin
lp:x:::lp:/var/spool/lpd:/sbin/login

• keep only numbers

[root@yong-02 sed]# sed 's/[^0-9]//g' test.txt |head -5
00
11
22
34
47

• delete all letters

[root@yong-02 sed]# sed 's/[a-zA-Z]//g' test.txt |head -5
::0:0::/://
::1:1::/://
::2:2::/://
::3:4:://://
::4:7::///://

• Use: as the division, and exchange the position of the first paragraph and the last paragraph; + is a special symbol in it, use -r to get rid of it

[root@yong-02 sed]# sed -r 's/([^:]+):(.*):([^:]+)/\3:\2:\1/'g test.txt
/bin/bash:x:0:0:root:/root:root
/sbin/nologin:x:1:1:bin:/bin:bin
/sbin/login:x:2:2:daemon:/sbin:daemon
/sbin/nologin:x:3:4:adm:/var/adm:adm
/sbin/login:x:4:7:lp:/var/spool/lpd:lp
/bin/sync:x:5:0:sync:/sbin:sync
/sbin/shutdown:x:6:0:shutdown:/sbin:shutdown
/sbin/halt:x:7:0:halt:/sbin:halt

• ; a semicolon can be matched multiple times

[root@yong-02 sed]# sed -n '/root/p;/adm/p' test.txt
root:x:0:0:root:/root:/bin/bash
adm:x:3:4:adm:/var/adm:/sbin/nologin

• -e make multiple commands, and ; effect one line

[root@yong-02 sed]# sed -n -e '/root/'p -e '/adm/'p  test.txt
root:x:0:0:root:/root:/bin/bash
adm:x:3:4:adm:/var/adm:/sbin/nologin

• Add aaa: & in front of each line to indicate the content of the previous ()

[root@yong-02 sed]# sed -r 's/(.*)/aaa:&/g' test.txt
aaa:root:x:0:0:root:/root:/bin/bash
aaa:bin:x:1:1:bin:/bin:/sbin/nologin
aaa:daemon:x:2:2:daemon:/sbin:/sbin/login
aaa:adm:x:3:4:adm:/var/adm:/sbin/nologin
aaa:lp:x:4:7:lp:/var/spool/lpd:/sbin/login
aaa:sync:x:5:0:sync:/sbin:/bin/sync
aaa:shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
aaa:halt:x:7:0:halt:/sbin:/sbin/halt

• Add aaa: \1 in front of each line to indicate the content of the previous ()

[root@yong-02 sed]# sed -r 's/(.*)/aaa:\1/g' test.txt
aaa:root:x:0:0:root:/root:/bin/bash
aaa:bin:x:1:1:bin:/bin:/sbin/nologin
aaa:daemon:x:2:2:daemon:/sbin:/sbin/login
aaa:adm:x:3:4:adm:/var/adm:/sbin/nologin
aaa:lp:x:4:7:lp:/var/spool/lpd:/sbin/login
aaa:sync:x:5:0:sync:/sbin:/bin/sync
aaa:shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
aaa:halt:x:7:0:halt:/sbin:/sbin/halt

• -i will directly change the content of the file itself, for example: sed -i 's/:/#/g' test.txt Change all ":" to "#"

[root@yong-02 sed]# sed -i 's/:/#/g' test.txt
[root@yong-02 sed]# cat test.txt
root#x#0#0#root#/root#/bin/bash
bin#x#1#1#bin#/bin#/sbin/nologin
daemon#x#2#2#daemon#/sbin#/sbin/login
adm#x#3#4#adm#/var/adm#/sbin/nologin
lp#x#4#7#lp#/var/spool/lpd#/sbin/login
sync#x#5#0#sync#/sbin#/bin/sync
shutdown#x#6#0#shutdown#/sbin#/sbin/shutdown
halt#x#7#0#halt#/sbin#/sbin/halt