>> The choice of "# " and "> " interests me. Because roots prompt of
>> "hash" has a side effect of making a cut-paste over it a comment in
>> most shells.
> 
> "#" as the root prompt predates # as the comment in the Bourne shell,
> not to mention predating copy/paste entirely. (My understanding is that
> the do-nothing command, ":" was used for comments. Talk about minimalist!)
> 
> Same point for ">", since copy/paste didn't exist in the late 70s when
> Bourne was doing the shell, it wasn't an issue.

As early as V5 the (thompson) shell prompts were “#” and “%”, and “:” for
a label. As the goto command exists in V4 (there is a man page for it), I
would assume that those characters were used in V4 as well. So it would
seem to go back to 1974.

In the V7 (bourne) shell the default non-root prompt is “$”. Goto is
dropped at this point.

Don’t know when or where “>” was first used on Unix as a prompt character
(on my boxes it still is “$”).

Paul