Yet more questions/problems with Interactive UNIX

[Guy Harris]

>sh and csh are stupid, ksh does the right thing.

More accurately, "'sh' and 'csh' let the stupid pre-S5R4 tty driver do
its thing, 'ksh' shoves the tty driver out of the way and does the line
editing itself, and it's smart enough to know when there's nothing left
to erase and stops echoing your erase character."

S5R4's driver *does* know when there's nothing left to erase; it also
knows how to erase tabs (i.e., it doesn't just echo BS-SP-BS).