Sed command (Stream Editor)

We are giving expression inside single quote using sed command. I am using this example for all the use cases.

Eg: ubuntu@ip-172-31-25-118:~$ cat data

ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 India

Use Cases:-

1. I want to change the name of first user Pol to Paul

Eg: ubuntu@ip-172-31-25-118:~$ sed 's/Pol/Paul/g' data

Output:

ID Name Salary Country

1 Paul 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 India

Here is the breakdown of a command

s: substitute

Pol: Which pattern you are searching for

Paul: This is your replacement string

g: global, means it will replace all instances of ‘Pol’ in each line.

2. I want to see the 2nd line from data file

Eg: ubuntu@ip-172-31-25-118:~$ sed -n '2p' data

Output: 1 Pol 25000 India

Here is the breakdown of a command

-n: It will print the data from 2nd line

2: second

p: printing

3. If I remove -n then print the 2nd data after the second line of your data.

Eg: ubuntu@ip-172-31-25-118:~$ sed '2p' data

Output:

ID Name Salary Country

1 Pol 25000 India

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 India

4. I want to see the last line

Eg: ubuntu@ip-172-31-25-118:~$ sed -n '$p' data

Output: 4 Hina 35000 India

5. I want to see the data from 2nd line to 4th line

Eg: ubuntu@ip-172-31-25-118:~$ sed -n '2,4p' data

Output:

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

6. I want to print the users which are from India

a) Using awk command

Eg: ubuntu@ip-172-31-25-118:~$ awk '/India/' data

Output:

1 Pol 25000 India

4 Hina 35000 India

b) Using sed command

Eg: ubuntu@ip-172-31-25-118:~$ sed -n '/India/p' data

Output:

1 Pol 25000 India

4 Hina 35000 India

7. Now we will using multiple expressions using -e flag. For example, if we want to see only 2nd and 4th line.

Eg: ubuntu@ip-172-31-25-118:~$ sed -n -e '2p' -e '4p' data

Output:

1 Pol 25000 India

3 Loki 55000 Germany

8. If you want to see the users from India and Germany

Eg: ubuntu@ip-172-31-25-118:~$ sed -n -e '/India/p' -e '/Germany/p' data

Output:

1 Pol 25000 India

3 Loki 55000 Germany

4 Hina 35000 India

9. Staring from 2nd line, I want to print next 2 lines

Eg ubuntu@ip-172-31-25-118:~$ sed -n '2,+2p' data

Output:

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

10. I want to print even lines of data

Eg ubuntu@ip-172-31-25-118:~$ sed -n '1~2p' data

Output:

ID Name Salary Country

2 Bont 45000 Belgium

4 Hina 35000 India

11. Now I am writing an expression on another file. Using sed command I want to execute the same expression and print the output.

This is my file

ubuntu@ip-172-31-25-118:~$ cat data1.txt

1p

2p

Eg: ubuntu@ip-172-31-25-118:~$ sed -n -f data1.txt data

Output:

ID Name Salary Country

1 Pol 25000 India

12. Now there is a word ‘India’ on 2nd line and 5th line. I want to change from India to US on 2nd line only.

ubuntu@ip-172-31-25-118:~$ cat data ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 India

Alternative way:

You can replace the word by searching Pol.

Eg: ubuntu@ip-172-31-25-118:~$ sed '/Pol/ s/India/US/g' data

Output:

ID Name Salary Country

1 Pol 25000 US

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 US

Eg: ubuntu@ip-172-31-25-118:~$ sed '2 s/India/US/g' data

ID Name Salary Country

Output:

1 Pol 25000 US

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 India

13. Wherever there is a word ‘India’, please change the word (except 2nd line)

Eg: ubuntu@ip-172-31-25-118:~$ sed '2! s/India/US/g'

Output:

data ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 US

14. Till now we are performing the operations on terminal itself, not inside the actual file. I want to change inside my actual file. You need to use ‘i’ flag

Eg: ubuntu@ip-172-31-25-118:~$ sed -i '2! s/India/US/g' data

ubuntu@ip-172-31-25-118:~$ cat data ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 US

15. I want to delete 1st line

Eg: ubuntu@ip-172-31-25-118:~$ sed '1d' data

Output:

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 US

16. Delete the last line of data

ubuntu@ip-172-31-25-118:~$ sed '$d' data

Output:

ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

17. Delete the data from 2nd line to 4th line

ubuntu@ip-172-31-25-118:~$ sed '2,4d' data ID

Name Salary Country

4 Hina 35000 US

18. Delete the user whose country is ‘Belgium’

ubuntu@ip-172-31-25-118:~$ sed '/Belgium/d' data

Output:

ID Name Salary Country

1 Pol 25000 India

3 Loki 55000 Germany

4 Hina 35000 US

19. Delete the empty line. Here is my actual data

ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 US

Eg: ubuntu@ip-172-31-25-118:~$ sed '/^$/d' data

this sed command will delete all blank lines (empty lines) from the file data when the command is run

Output:

ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 US

Now this is my file

ubuntu@ip-172-31-25-118:~$ cat > Country

India

Germany

I want to list the country which is Germany

ubuntu@ip-172-31-25-118:~$ sed -n '/^G/p' Country

Germany

I want to list the country which ends with character ‘a’.

ubuntu@ip-172-31-25-118:~$ sed -n '/a$/p' Country

India

Character Sets:-

I want to list country which starts from ‘I’ or ‘G’

ubuntu@ip-172-31-25-118:~$ sed -n '/[IG]/p' Country

India Germany

I want to list the country having range from A to I

ubuntu@ip-172-31-25-118:~$ sed -n '/[A-I]/p' Country

India

Germany

Brietta

20. I want to add the user who are from India in a new file called ‘IndianUsers’

Eg: ubuntu@ip-172-31-25-118:~$ sed '/India/ w IndianUsers' data

Output:

ubuntu@ip-172-31-25-118:~$ cat IndianUsers

1 Pol 25000 India

21. I want to append the data after 3rd line

Eg: ubuntu@ip-172-31-25-118:~$ sed '3 a Hello User' data

Output:

ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

Hello User

3 Loki 55000 Germany

4 Hina 35000 US

22. I want to edit the 2nd line to ‘Hello User’

ubuntu@ip-172-31-25-118:~$ sed '2 c Hello User' data

Output:

ID Name Salary Country

Hello User

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 US

23. I want to append or insert data before 1st line

ubuntu@ip-172-31-25-118:~$ sed '1 i Hello User' data

Output:

Hello User

ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

3 Loki 55000 Ger

24. I want to check hidden character in my file

ubuntu@ip-172-31-25-118:~$ sed -n 'l' data

Output:

ID Name Salary Country$

1 Pol 25000 India$

2 Bont 45000 Belgium$

3 Loki 55000 Germany$

4 Hina 35000 US$

25. We can wrap the content. Like if you want to display only 10 characters in a line.

Eg: ubuntu@ip-172-31-25-118:~$ sed -n 'l 10' data

ID Name S alary Cou ntry$ 1 Pol 250 00 India$ 2 Bont 45 000 Belgi um$ 3 Loki 55 000 Germa ny$ 4 Hina 35 000 US$

Suppose I have created new file

ubuntu@ip-172-31-25-118:~$ cat ExternalFile

Hello User, this is a external file

26. I want to insert this data after 3rd line in my original data.

ubuntu@ip-172-31-25-118:~$ sed '3 r ExternalFile' data → Here r stands for Read

ID Name Salary Country

1 Pol 25000 India

2 Bont 45000 Belgium

Hello User, this is a external file

3 Loki 55000 Germany

4 Hina 35000 US

27. It prints the 1st line of those user whose country is India and after that it stops the execution.

ubuntu@ip-172-31-25-118:~$ sed '/India/ q' data

ID Name Salary Country

1 Pol 25000 India

28. To add the date in 3rd line

ubuntu@ip-172-31-25-118:~$ sed '3 e date' data

ID Name Salary Country

1 Pol 25000 India

Sat Sep 14 14:26:53 UTC 2024

2 Bont 45000 Belgium

3 Loki 55000 Germany

4 Hina 35000 India

29. To know on which line number you have inserted which data

ubuntu@ip-172-31-25-118:~$ sed '=' data

1

ID Name Salary Country

2

1 Pol 25000 India

3

2 Bont 45000 Belgium

4

3 Loki 55000 Germany

5

4 Hina 35000 India

30. If you want to list out the files ending with .txt

ubuntu@ip-172-31-25-118:~$ ls -ltr *.txt

-rw------- 1 ubuntu ubuntu 66 Sep 9 07:53 testing.txt

-rw-rw-r-- 1 ubuntu ubuntu 37 Sep 9 14:23 tester.txt

-rw-rw-r-- 1 ubuntu ubuntu 6 Sep 13 14:11 data1.txt

31. ls -ltr: list the files in long format where

-t: display the newest modified files

-r: sorts the files in ascending order