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This article will explain in detail how to use the sed command in the linux server. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.

Sed:Stream Editor text stream editing, sed is a "non-interactive" character stream-oriented editor. Can handle the contents of multiple files and multiple lines at the same time, you can input the whole file to the screen without changing the original file, and you can input the content that only matches the pattern to the screen. You can also make changes to the original file, but the results are not returned on the screen.

The syntax format of the sed command:

Sed command format: sed [option] 'sed command'filename

Sed script format: sed [option]-f 'sed script'filename

Options for the sed command (option):

-n: print only lines that match the pattern

-e: edit sed actions directly on the command line mode, which is the default option

-f: write the actions of sed in a file, and use-f filename to execute sed actions in filename.

-r: support for extended expressions

-I: modify the file content directly

How sed queries the text in a file:

1) use a line number, which can be a simple number or a range of line numbers

X

X is the line number

X,y

Indicates the line number is from x to y

/ pattern

Query rows that contain schemas

/ pattern / pattern

Query rows with two schemas

Pattern/,x

Query rows containing patterns on a given line number

X,/pattern/

Query matching rows by line number and pattern

X,y!

The query does not contain rows with specified line numbers x and y

2) use regular expressions, extend regular expressions (must be combined with the-r option)

^

The qualified content at the beginning of the anchor line in the usage format "^ pattern"

$

The qualified content of the anchor line header, the usage format "pattern$"

^ $

Blank line

.

Match any single character

*

Match the character immediately preceding it any number of times (0meme1, multiple times)

. *

Match any character of any length

\?

Match the character immediately before it 0 or 1 times

\ {mdirection n\}

Match the characters before them at least m times and n times at most

\ {m,\}

Match the characters before them at least m times

\ {m\}

Exactly match the previous m times\ {0jue n\}: 0 to n times

\ pattern

\

Word anchor

\ (\)

Grouping, usage format:\ (pattern\), references\ 1,\ 2

[]

Matches any single character within the specified range

[^]

Matches any single character outside the specified range

[: digit:]

All numbers, equivalent to 0-9, [0-9]-- > [[: digit:]]

[: lower:]

All lowercase letters

[: upper:]

All capital letters

[: alpha:]

All the letters.

[: alnum:]

Equivalent to 0-9a-zA-Z

[: space:]

White space character

[: punct:]

All punctuation marks

The code is as follows:

The matching pattern of # sed supports regular expressions #

The first 5 lines of sed'5 q'/etc/passwd# print

Sed-n'/ r*t/p'/etc/passwd# prints lines that match r with 0 or more, followed by a t character

Sed-n'/ .r. * / p'/etc/passwd# print matches the line with r followed by any character

Sed-n'/ o*/p'/etc/passwd# print o characters are repeated any number of times

The sed-n'/ o\ {1,\} / p'/etc/passwd# print o word is repeated more than once.

Sed-n'/ o\ {1pr 3\} / p'/etc/passwd# print the word o repeats between one and three times.

Edit command (sed command) for sed:

P

Print matching lines (used with the-n option)

=

Show file line number

A\

Append new text information after locating the line number

I\

Insert new text information after locating the line number

D

Delete positioning line

C\

Replace positioned text with new text

W filename

Write text to a file, similar to output redirection >

R filename

Read text from another file, similar to input redirection > myfile hello world

> i am jie

> how are you

> Mr. EOF # into one document

[root@jie1 ~] # cat myfile

Hello world

I am jie

How are you

[root@jie1 ~] # name=li

# define a variable and assign a value to it

[root@jie1] # sed-I "s/jie/$name/" myfile

# replace the characters that match jie with the value of the variable

[root@jie1 ~] # cat myfile

Hello world

I am li

How are you

[root@jie1 ~] # sed-I "$a $name" myfile

# when the sed command also has default variables, syntax errors will occur when referencing self-defined variables

Sed:-e expression # 1, char 3: extra characters after command

[root@jie1 ~] # sed-I'$a'$name'' myfile

# when referencing a custom variable, the sed statement must enclose it in single quotation marks, and then enclose the custom variable in single quotation marks

[root@jie1 ~] # cat myfile

Hello world

I am li

How are you

Li

[root@jie1 ~] #

Other advanced uses of sed:

1) write the contents of the file being operated with sed to an exception file

The code is as follows:

[root@jie1 ~] # cat test # contents of sed operation

Ethernet

# BOOTPROTO= "dhcp"

HWADDR= "00:0C:29:90:79:78"

ONBOOT= "yes"

IPADDR=172.16.10.12

NETMASK=255.255.0.0

[root@jie1] # sed-I 's/IPADDR/ip/w ip.txt' test

# Save the file content of the sed operation to another file, w means save, and ip.txt file name

[root@jie1 ~] # cat ip.txt # View the contents of the new file

Ip=172.16.10.12

[root@jie1 ~] #

2) read a file to the file that is being operated with sed

The code is as follows:

[root@jie1 ~] # cat myfile # file content

Hello world

I am li

How are you

Li

[root@jie1 ~] # cat test # the contents of the file to be manipulated with sed

Ethernet

# BOOTPROTO= "dhcp"

HWADDR= "00:0C:29:90:79:78"

ONBOOT= "yes"

IPADDR=172.16.10.12

NETMASK=255.255.0.0

[root@jie1 ~] # sed-I'/ Ethernet/r myfile' test

# in the line that matches Ethernet, read in the contents of another file, and the contents of the read file will be inserted after the line that matches Ethernet

[root@jie1 ~] # cat test # look at the line operated with the sed command again

Ethernet

Hello world

I am li

How are you

Li

# BOOTPROTO= "dhcp"

HWADDR= "00:0C:29:90:79:78"

ONBOOT= "yes"

IPADDR=172.16.10.12

NETMASK=255.255.0.0

[root@jie1 ~] #

Classic example of sed:

The code is as follows:

# # 1) process the contents of the following files, take out the domain name and sort it by counting, such as processing:

Http://www.baidu.com/index.html

Http://www.baidu.com/1.html

Http://post.baidu.com/index.html

Http://mp3.baidu.com/index.html

Http://www.baidu.com/3.html

Http://post.baidu.com/2.html

The results are as follows:

Number of occurrences of domain names domain names

3 www.baidu.com

2 post.baidu.com

1 mp3.baidu.com

[root@localhost shell] # cat file | sed-e 's/http:\ /\ / /'- e's /\ /. * / /'| sort | uniq-c | sort-rn

3 www.baidu.com

2 post.baidu.com

1 mp3.baidu.com

[root@codfei4 shell] # awk-F /'{print $3} 'file | sort-r | uniq-c | awk' {print $1 "\ t", $2}'

3 www.baidu.com

2 post.baidu.com

1 mp3.baidu.com

# # 2) use grep and sed to remove the ip address of the network card

[root@jie1 ~] # ifconfig | grep-B1 "inet addr" | grep-v "\ -\ -" | sed-n-e'Npolitics /\ (eth [0-9]\). *\ n.*addr:\ ([0-9]\ {1jue 3\}\. [0-9]\ {1jue 3\}\. [0-9]\ {1jue 3\}\). * /\ 1\ 2cannon\).

This is the end of the article on "how to use sed commands in the linux server". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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