ZZ is the first vi command I learned. After typing vi and only seeing a column of ~s, I asked how do I get out of this thing. Someone answered - ZZ.

You are welcome! I’m happy to hear it!

I teach a vi basics tutorial and I get that a lot. :)

http://vitutorial.org/

The tutorial is based on Bill Joy’s original paper introducing the vi editor.

Maybe you’ll find something else new there. :)

I just learnt it the other day, as well. Granted, it was from chapter 1 of "Learning the vi and vim Text Editors" but shhh