Summary of usage of SED

In the study and use of Linux, the importance of sed,awk,grep usage is self-evident, this article summarizes the usage of SED from the following aspects:

1, the meaning of sed

The SED is the stream editor, and that is the flow editors, and the vi we use is different, and VI is the full screen editor. and SED is to row the contents of the file into memory, in the SED to specify the command to process, and then output to the screen.

2. Use and format of SED

sed [options] ' Startadd,endaddcommand ' files,...

[Options] refers to the option of SED. Can omit

Startadd,endadd refers to the representation of addresses in SED

Command refers to the processing of SED commands.

Files,.. Can be multiple, which is the processing object of the SED. Put that file in memory and then line it up.

3. How the address is represented

' 1,3p ' passwd #表示的含义是, print passwd files 1 through the third line. Absolute line number notation

[Email protected] testdir]# sed-n ' 1,3p ' passwd

Root:x:0:0:root:/root:/bin/bash

Bin:x:1:1:bin:/bin:/sbin/nologin

Daemon:x:2:2:daemon:/sbin:/sbin/nologin

' 1,+3p ' passwd #表示的含义是: Prints the contents of the first line and the following three lines. Relative line number notation

[Email protected] testdir]# sed-n ' 1,+3p ' passwd

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

' $p ' passwd #表示打印从38行到最后一行的passwd的内容 $ represents the last line

[Email protected] testdir]# sed-n ', $p ' passwd

User1:x:504:504::/home/user1:/bin/bash

User2:x:505:505::/home/user2:/bin/bash

User3:x:506:506::/home/user3:/bin/bash

'/pattern/command ' #表示匹配到patern的行打印, pattern can be a regular expression

[Email protected] testdir]# sed-n '/^root/p ' passwd

Root:x:0:0:root:/root:/bin/bash

Rootbisu:x:500:500:centos_x641:/home/rootbisu:/bin/bash

'/pattern1/,/pattern2/command ' uses the Command to handle the/pattern1/first match to the row, to/pattern2/the first match to the contents of the line

[Email protected] testdir]# sed-n '/^\<root\>/,/^\<bin\>/p ' passwd

Root:x:0:0:root:/root:/bin/bash

Bin:x:1:1:bin:/bin:/sbin/nologin

sed ' 3p ' passwd # indicates the third line of print passwd

[Email protected] testdir]# sed-n ' 3p ' passwd

Daemon:x:2:2:daemon:/sbin:/sbin/nologin

4. Use of commands and parameters in SED

Since SED is a stream editor, his main command function should be on the editor. Common editing operations include, print, delete, replace, add, and so on.

d: To delete rows that match the criteria

P: Indicates that the line that matches the criteria is printed

A: After qualifying the line , format: a\string append new Content A is append # A after what the output is. [[Email protected] testdir]# sed '/^\<root\>/a\appendtest ' passwd

Root:x:0:0:root:/root:/bin/bash

Appendtest

I:insert, the table inserts a new string before qualifying rows. Format i\string

[[Email protected] testdir]# sed '/^\<root\>/i\appendtest ' passwd

Appendtest

Root:x:0:0:root:/root:/bin/bash

R:read, Rfile indicates that the contents of the read file are appended after the qualifying row

[[Email protected] testdir]# sed '/^\<root\>/rgrep.txt ' passwd

Root:x:0:0:root:/root:/bin/bash

This is root

The user is Mroot

Rooter is a dog ' s name.

Mrooter is not a word

Bin:x:1:1:bin:/bin:/sbin/nologin

W:write,wfile indicates that the qualifying line is written to file

[Email protected] testdir]# sed-n '/^\<root\>/wgrep.txt ' passwd

[email protected] testdir]# cat Grep.txt

Root:x:0:0:root:/root:/bin/bash

s means find and replace # Replace the first match to the item

[[Email protected] testdir]# sed ' s/root/root/' passwd

Root:x:0:0:root:/root:/bin/bash

# plus the parameter G means replace all matches to the item

[[Email protected] testdir]# sed ' s/root/root/g ' passwd

Root:x:0:0:root:/root:/bin/bash

5, the commonly used parameters:

-N: Indicates silent mode, output only processed rows, other outputs

-I: Will effect the command result on the processed file

-R: Indicates that extended regular expressions can be used in pattern

-E: Indicates that multiple commands can be used. Sed-e ' 10,11p '-e ' 12,13d '

6, the summary of the use of SED and matters needing attention

The use of SED is critical, and it is important to remember that the use and format of the SED, the representation of the address, and the commands used, as well as the parameters of the command, and the details that need to be noted here are the latter references that can be used in sed.

There is a text content as follows:

He like he

She love hers love

He like his love

She love he like

There is a need, want to turn like into Liker, want to turn love into lover should be how to deal with? This time you can use the latter reference.

[Email protected] testdir]# sed ' s/\ (L. e\)/\1r/g ' test

He liker his liker

She lover her lover

He liker his lover

She lover her liker

[Email protected] testdir]# sed ' s/\ (L. e\)/\ (l,,e\) r/g ' test

He (L,,e) r his (l,,e) r

She (L,,e) r Her (l,,e) r

He (L,,e) r his (l,,e) r

She (L,,e) r Her (l,,e) r

Note that we find that ' s/string1/string2/g ' where string can be a regular expression, and if the-r option is used, you can also use an extended regular expression, but string2 cannot use regular expressions.

Summary of usage of SED