How to delete a specific line from a text file using the SED command?

You can use Vim or Nano Wait for the text editor , Enter the file and delete the required lines , however , This method is not suitable for use bash Scripts are automated .

contrary , You can use powerful sed Command line editor and delete lines that meet specific conditions , Of course , You can go to shell Use in script sed.

Delete the... From the file n That's ok

Imagine , You must delete the... In the file 7 Line number , You can use... Like this sed command ：

sed -i '7d' filename

Let me explain how it works ：

• -i： This option enables in place editing , By default ,sed Only output will be displayed . Use this -i Options , It will modify the actual file without displaying it on the display .
• 7d: here 7 Is the line number ,d Indicates to delete the line .
• filename: This is the file you want to modify , If the file is in another directory , You can also provide absolute or relative paths .

Let me use a real example to show , This one is called wljslmz.txt Sample text file ：

 Learning technology 
 Go to the network technology alliance station 
 Find tutorial 
 Also on the network technology alliance station 
 Increase knowledge 
 Also on the network technology alliance station 
 Add salary 
 You must go to the network technology alliance station 

To delete the 4 That's ok , I use ：

sed '4d' agatha.txt

This will cause the following display to be deleted “ Also on the network technology alliance station ” That's ok ：

 Learning technology 
 Go to the network technology alliance station 
 Find tutorial 
 Increase knowledge 
 Also on the network technology alliance station 
 Add salary 
 You must go to the network technology alliance station 

Now? , Suppose you want to be in Linux Delete the first line of the file on the command line , Use... Like this sed：

sed -i '1d' filename

If you want to view the operation results without modifying the file itself , Please do not use -ised Command options .

Use sed Delete last line

You learned to delete specific lines , But what if you need to delete the last line ？

You may always use wc Command to get the total number of rows in the file , And compare this number with sed Use it together . however ,sed There is a special method to delete the last line of the file , You don't have to worry about the number of files anymore .

sed -i '$d' filename.txt

Delete a series of lines

Similar to what you saw before , You can also delete a series of lines from the file .

Suppose you have to delete from 11 To 15 The line of , You can provide such a range ：

sed -i '11,15d' filename

Please note that , It will also delete section 11 Xing He 15 That's ok , Not just the rows between them .

Delete lines that contain strings

You can also use it sed Delete all lines that contain a given string or match a specific pattern .

The following command will delete all containing words ‘string’ The line of ：

sed -i '/string/d' filename

Please note that , This is a case sensitive search , You can also use regular expression patterns instead of regular strings .

Delete lines beginning with words

If you want to delete all lines that begin with a specific word or letter , Just provide the following regular expression pattern ：

sed -i '/^word/d' filename

Additional tips ： Delete all blank lines

Before I finish this article , Let me quickly share how to use sed Delete all blank lines ：

sed -i '/^$/d' filename