Grep ipv4 addresses grep -Eo '([0-9]*\.){3}[0-9]*' Grep for html title, -o only matching part, -e match pattern grep -oiE "<title>(.*)</title>" Grep for subdomains grep -RiEo '([a-zA-Z0-9-]+\.)*domain\.com' * Grep logical or grep -E "pattern1|pattern2" Grep for strings inside binary file grep --text "<string>" <file> Find lines in one file that are not in another grep -v -f <file1> <file2> Print X char around string grep -Eio ".{0,20}string.{0,20}" Search for files that does contain an e-mail address grep -LEiR '([[:alnum:]_.-]+@[[:alnum:]_.-]+?\.[[:alpha:].]{2,6})' "$@"