grep

A command-line search tool that finds patterns in text — short for Global Regular Expression Print. 

In simple terms: it hunts through files and tells you where the thing you’re looking for is hiding.

Grep is a command-line utility that can search and filter text using a common regular expression syntax, which explains why the word grep is sometimes used to simply mean “to search for”.

Grep finds all occurrences of a search term in a text file, a selection of files or the output of another command.

Examples

Return instances of the search term “Emily” in the provided file:

grep "Emily" ~/applicants.txt

Returns lines that do not contain “Referred by Emily”:

grep -v "Referred by Emily" ~/applicants.txt

Returns lines that do not contain “Referred by Emily” or “Referred by John M”:

grep -v -e "Referred by Emily" -e "Referred by John M" ~/applicants.txt