command completion

[utzoo!decvax!duke!chico!esquire!psl]

The "original" Harvard Unix system did pdp10 style command completion
by having a repertoire of known commands (i.e. a directory that was
used as the repertoire).  I, for one, found this a little too helpful.
That shell was replaced by a shell which had optional command completion
keyed by the escape key; e.g. "re[ESC]" becomes "rename" as you type it.
This shell also had other handy features.  Escape by itself expanded to the
previous command, and since it did it "before your eyes" you could edit it
with the standard editing characters ([DEL] for char delete, ^U for line kill,
^R for retype the line, etc.).  Thus you could type
"nroff -T300S -e -h -rx3 /usr/pub/macros/tug.nr section3.nr"
and after seeing that the output on the terminal was what you wanted type
the escape key followed by ">outfile" to do it again into a file.  Csh has
similar functionality, but requires more blind faith since you don't see the
command until you've committed to it.
I imagine Harvard is still using this shell (mostly Tucker Taft's work).