This is what i used to edit configurations in plan9 console if you don't have graphics support(over serial console) or to fix issues before starting rio. It is surprisingly pretty decent experience.
you joke, but ed is great if have tiny change to make given compiler output simply just to how fast it loads
I used to use ed when all I had was a single terminal screen/window and a compiler error message. Ed doesn't clear the screen, so you can still see the message. Vi or emacs would clear the error message away. Of course, in a multi-window situation, the compiler output is usually in one window or pane and the editor in another, so this is moot now.
I got a local login on a machine so busted that I couldn't mount /usr, meaning I couldn't read /usr/share/terminfo, meaning no screen editors would work. I knew just enough ed that I was able to fix /etc/fstab and bring the system up.
I wouldn't wanna use it every day, but it has its time and place.
"busybox vi" is another option in these situations when that's available. It will happily run in a blank chroot.
Everybody should know a little ed though, it's not that hard.
It was on a server that didn't have busybox installed. Also, can busybox vi work without access to termcap or terminfo?
Honestly at that point, unless your fstab is really big, I'd just `cat /etc/fstab` and then `cat >/etc/fstab <<EOF` and very carefully retype it (I mean take a backup first of course).