Search and Replace Multiple Lines using sed

Overview

sed is my go to Linux command when I want to search and replace multiple words in a file. The syntax for the sed command is:

sed [options] 'command' file

the best way to understand it is with a few examples

Example: Search and Replace a Word in a File

replace the first occurrence of the word pattern on each line with replacement, using the s parameter

sed 's/pattern/replacement/' filename

Example: Search and Replace Multiple Words in a File

add a g to the end to replace all occurrences of the word pattern with replacement

sed 's/pattern/replacement/g' filename

now so far these just print the result. If you want to commit and actually update the file with the changes you need the -i option

Example: Search and Replace and Save the File

here we change enforcing to permissive, and using the -i flag writes the change to the /etc/selinux/config file

sed -i 's/enforcing/permissive/' /etc/selinux/config

Example: Search and Replace and make a backup file

in case you want to role back the change use -i.bak to make a copy of the original file with .bak appended

sed -i.bak 's/enforcing/permissive/' /etc/selinux/config

Summary

so there you have it, search and replace quickly and efficiently on the command line with sed. Because it uses regex there are many more automations that can be done. see the sed man pages for more ideas.