Nobody has mentioned screen. This is unacceptable! screen is extremely reliable and useful. I'd like to say emacs, but it's not really that "reliable" in that

Nobody has mentioned screen. This is unacceptable! screen is extremely reliable and useful. I'd like to say emacs, but it's not really that "reliable" in that it often goes crazy and eats up a CPU, and I must maintain separate .emacs files for slightly different computers and vintages of emacs. It does work very well though.