This Old Dog is digging using Joe as my terminal editor in Linux. It's a WordStar clone and the 90's were a good time for me as a Techster. Below is a screenshot of the Joe Editor in action. You can hide the Help Info at top of screen, but I'm including it to give it a sweeter WordStar vibe.
Notice that the UNDO sequence is ^_, or CTRL-[Underscore]. For those of us using Linux, and in particular, a desktop environment with a Gnome origin like Cinnamon, ^_ will give you a reduced terminal and font rendering and nothing more.
When you're getting comfortable with Joe you want to have an Undo keyboard shortcut at the ready! Out of the box, you can use ^& for Undo. It's logical if you think about it, since ^^ or Redo is right next door. I actually discovered that accidentally, though it made logical sense as I said.
If you're prone to forget that like me, go ahead and update the Help Info Display! Simply copy /etc/usr/joe/joerc to ~/.joerc and modify as you see fit. You can change the actual bindings if you want, but it's not necessary. I think it's sufficiently cool to see ^& Undo in the Help Display.
Here's a NixMashup Link where I first mentioned the Joe Editor with more information on installing it in your favorite Linux distribution