Search text files with grep

The grep tool is built into the operating system, so you don’t need to install it.

The simplest syntax to find a string in a single file using the grep command is:
grep ‘searched-word’ filename

By default, the search with grep is case sensitive.

Let’s gradually add the most useful options to our search.

1. Make the search case-insensitive with the "-i" option:
grep -i 'searched-word' filename

2. Search recursively in all files in a given directory with the "-r" option:
grep -ir 'searched-word' '/directory'

3. Search whole words only with the "-w" option:
grep -irw 'searched-word' '/directory'

4. Print the line numbers in which the searched word was found with the "-n" option:
grep -irwn 'searched-word' '/directory'

5. Search for multiple words syntax:
grep -ir 'word1|word2|word3' '/directory'

Many other useful grep options can be found in the official Grep Manual.