How to find and replace text using sed command

SED is a command-line utility in Unix/Linux systems that stands for stream editor. It is capable to search and replaces text in a file. With the help of the sed utility, you can directly replace a string with another string without editing the file.

In this tutorial, you will learn to replace a string in a file using the Sed command-line utility.

Sed Command to Replace String

The following command will search for all strings “Hello” in the welcome.txt file. Then replace it with a new string “Howdy” in the same file.

sed -i 's/Hello/Howdy/g' welcome.txt 

The above command will make changes in the same file. But if you want to create a backup of file before making any changes, use command as:

sed -i.backup 's/Hello/Howdy/g' welcome.txt 

This will create a file welcome.txt.backup in the current directory with the original file content.

Sed Replace Text in Multiple file

The Following command is helpful to replace strings in multiple files at once in a directory /opt/docs. Here find will navigate to all files under the defined directory and execute the sed command one by one.

find /opt/docs/ -type f -exec sed -i 's/Hello/Howdy/g' {} ; 

Sed Replace Text Without Affecting Original File

If you do not want to make changes in your original file and create new files with changed strings, use the following command.

sed 's/Hello/Howdy/g' welcome.txt > welcome_2.txt 

This command will create a new file welcome_2.txt with modified text. The original file with remain unchanged.

Conclusion

In this tutorial, you have learned about replacing text in files with Sed command-line utility.