Terminal is a way of getting to the Unix underpinnings of Apple’s Mac OS X operating system. It is generally kept out of the way because an uneducated user could do a lot of damage. I have put together eight of my favourite life hacks using Terminal here. Your mileage will vary. Over time Apple has stopped supporting some commands and introduced others grep used to come in handy for finding and removing duplicate files. A new command called ditto makes it really easy to make copies of folders.
I have put together each of these as a presentation as well