xampp (the linux version of mamp) includes its own mysql, and doesn’t add anything to the path (so you can’t use the command without a path).
try using the path to mamp’s mysql (I am **guessing** that it is something like `/Applications/MAMP/Library/bin/mysql` – you’ll need to check and make sure!!!)
(continue if it says it is already running)
/Applications/MAMP/Library/bin/mysql -u root -p
(type your password)
follow @AlenAbdula’s steps