Linux cheatsheet

Search and Replace in Multiple Files

perl -pi -w -e 's/search/replace/g;' *.php

Source: How to do a search and replace over multiple files

Compare two strings (when one of them is a subprocess)

 diff <(md5 -q ~/Downloads/ubuntu-16.04.1-desktop-amd64.iso) <(echo "17643c29e3c4609818f26becf76d29a3")

Source: Process Substitution