20 Practical Sed Command Examples for Linux Users

As a Linux user, understanding the power of command-line tools is essential for efficient system management and text manipulation. Among the various tools available, Sed (Stream Editor) stands out as a versatile utility that allows to transform, modify, and manipulate text  files effortlessly.

In this blog post, we will explore 20 practical sed command examples that will empower you to perform complex text editing tasks with ease. So, let’s dive into the world of sed and unlock its potential!




Now let’s see some examples.

1) Print Specific Lines

With sed, we can print specific lines of a file rather than seeing whole file. So, to print specific lines of a file, use the following command,

$ sed -n 22,29p testfile.txt

here, option ‘n’ suppresses printing of whole file & option ‘p’ will print only line lines from 22 to 29.

2) Print all except some lines

To print all content of a file except for some portion, use the following command,

$ sed 22,29d testfile.txt

Option ‘d’ will remove the mentioned lines from output.

3) Display every 3rd line starting with Nth line

Do display content of every 3rd line starting with line number 2 or any other line, use the following command

$ sed -n '2~3p' file.txt

Insert Text Before a Specific Line:

$ sed '4i\inserted-text' filename

Append Text After a Specific Line:

$ sed '4a\appended-text' filename

4 ) Deleting a line using sed command

To delete a line with sed from a file, use the following command,

$ sed Nd testfile.txt

where ‘N’ is the line number & option ‘d’ will delete the mentioned line number. To delete the last line of the file, use

$ sed $d testfile.txt

5) Deleting a range of lines

To delete a range of lines from the file, run

$ sed '29,34d' testfile.txt

This will delete lines 29 to 34 from testfile.txt file.

Deleting all empty lines:

In order to delete all the empty or blank lines from a file, use the following command:

$ sed '/^$/d' filename

6) Deleting lines other than the mentioned

To delete lines other than the mentioned lines from a file, we will use ‘!’

$ sed '29,34!d' testfile.txt

here ‘!’ option is used as not, so it will reverse the condition i.e. will not delete the lines mentioned. All the lines other 29-34 will be deleted from the files testfile.txt.

7) Adding Blank lines

To add a blank line after every non-blank line, we will use option ‘G’,

$ sed G testfile.txt

Replace Tabs with Spaces:

$ sed 's/\t/ /g' filename

8) Search and Replae a string

To search & replace a string from the file, we will use the following example,

$ sed 's/danger/safety/' testfile.txt

here option ‘s’ will search for word ‘danger’ & replace it with ‘safety’ on every line for the first occurrence only.

9) Search and Replace a string from whole file

To search and replace a string globally from the file, we will use option ‘g’  with ‘s’ as shown in the example below,

$ sed 's/danger/safety/g' testfile.txt

10) Replace the nth occurrence of string pattern

We can also substitute a string on nth occurrence from a file. Like replace ‘danger’ with ‘safety’ only on second occurrence,

$ sed ‘s/danger/safety/2’ testfile.txt

To replace ‘danger’ on 2nd occurrence of every line from whole file, use

$ sed 's/danger/safety/2g' testfile.txt

11) Substitute Text on a Specific Line

To search and replace a string on the specific line, use below command

$ sed '4 s/danger/safety/' testfile.txt

This will only substitute the string from 4th line of the file. We can also mention a range of lines instead of a single line,

$ sed '4,9 s/danger/safety/' testfile.txt

12) Add a line after/before the matched search

To add a new line with some content after every pattern match, use option ‘a’ ,

$ sed '/danger/a "This is new line with text after match"' testfile.txt

To add a new line with some content a before every pattern match, use option ‘i’,

$ sed '/danger/i "This is new line with text before match" ' testfile.txt

13) Change a whole line with matched pattern

To change a whole line to a new line when a search pattern matches we need to use option ‘c’ with sed,

$ sed '/danger/c "This will be the new line" ' testfile.txt

So when the pattern matches ‘danger’, whole line will be changed to the mentioned line.

Advanced options with sed

Up until now we were only using simple expressions with sed, now we will discuss some advanced uses of sed with regex,

14) Running multiple sed commands

If we need to perform multiple sed expressions, we can use option ‘e’ to chain the sed commands,

$ sed -e 's/danger/safety/g' -e 's/hate/love/' testfile.txt

15) Making a backup copy before modifying a file

To create a backup copy of a file before we edit it, use option ‘-i.bak’,

$ sed -i.bak -e 's/danger/safety/g'  testfile.txt

This will create a backup copy of the file with extension .bak. You can also use other extension if you like.

16) Delete a file line starting with & ending with a pattern

To delete a line starting with a particular string & ending with another string, use

$ sed -e 's/^danger.*stops$//g' testfile.txt

This will delete the line with ‘danger’ on start & ‘stops’ in the end & it can have any number of words in between , ‘.*’ defines that part.

Delete Leading Whitespace:

$ sed 's/^[[:space:]]*//' filename

Remove Trailing Whitespace:

$ sed 's/[[:space:]]*$//' filename

17) Appending lines

To add some content before every line with sed & regex, use

$ sed -e 's/.*/testing sed &/' testfile.txt

So now every line will have ‘testing sed’ before it.

18) Removing all commented lines, empty line and duplicate lines

To remove all commented lines i.e. lines with # & all the empty lines,  use

$ sed -e 's/#.*//;/^$/d' testfile.txt

To only remove commented lines, use

$ sed -e 's/#.*//' testfile.txt

Remove Duplicate Lines:

$ sed '$!N; /^\(.*\)\n\1$/!P; D' filename

19) Get list of all usernames from /etc/passwd

To get the list of all usernames from /etc/passwd file, use

$ sed 's/\([^:]*\).*/\1/' /etc/passwd

a complete list all usernames will be generated on screen as output.

20) Prevent overwriting of system links with sed command

‘sed -i’ command has been known to remove system links & create only regular files in place of the link file. So to avoid such a situation & prevent ‘sed -i‘ from destroying the links, use ‘–follow-symklinks‘ options with the command being executed.

Let’s assume i want to disable SELinux on CentOS or RHEL Severs

$ sudo sed -i --follow-symlinks 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/sysconfig/selinux

These were some examples to show sed, we can use these reference to employ them as & when needed.


Congratulations on reaching the end of this comprehensive Sed command examples guide! You have acquired a solid foundation in using Sed to manipulate and transform text in Linux. Remember, Sed is a powerful tool that can simplify complex text editing tasks and improve your productivity as a Linux user. So, go ahead and experiment with these examples, unleash your creativity, and master the art of text manipulation with Sed!.

If you guys have any queries related to this guide, kindly post your queries in below comments section.

Also Read: 14 SCP Command Examples to Securely Transfer Files in Linux

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I am a Cloud Consultant with over 15 years of experience in Linux, Kubernetes, cloud technologies (AWS, Azure, OpenStack), automation (Ansible, Terraform), and DevOps. I hold certifications like RHCA, CKA, CKAD, CKS, AWS, and Azure.

4 thoughts on “20 Practical Sed Command Examples for Linux Users”

  1. Thanks. I’ve a question. Wondering if you can help me with this.

    How do I append text


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  2. range of lines is , in sed toool and not -. Examples 1,2,3,5 and 6 need update.
    Use tilde ~ instead of – in example 3
    Rest all very useful


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