[rswail]

I first used ed(1) back in the ye olden days of early 1980s, vi was like a major advance.

Came in handy when I had to talk a guy through updating a Solaris config file to allow the box to boot when he only had a serial console in the early 2000s.

[mghackerlady]

ed is good. If, for whatever reason, I was forced to only use line mode editors for the rest of time, you can't do much better than ed (besides ex, I suppose)