Grep

Grep is an extremely versatile tool, and is used to locate patterns and specific words or phrases.

Tip: You may combine various commands together!

Searching for a Word or Phrase

The command grep --help will display the multitude of arguments you may pass to grep. Here's a few common examples:

grep -i "cheddar" cheeseList.txt

The above snippet calls grep and asks it to look for the word cheddar in the cheese list text file. -i indicates to ignore case when returning results.

Counting Instances of a Word or Phrase

If you wanted to see how many times a certain word or phrase pops up in a file, use -c for count.

grep -c "login failed" authLogs.txt

These are a couple of basic examples. Grep is extremely powerful, especially when chained with other commands.

Reference

https://www.geeksforgeeks.org/linux-unix/grep-command-in-unixlinux/