Re: Differences between Duff's rc and Byron's

[haahr@mv.us.adobe.com (Paul Haahr)]

if you look at the unix version (10th edition) of rc rather than
the plan 9 version, some of the differences drop away.  all of the
following are in the bell labs unix version of rc, either exactly
or almost identical to the versions in Byron's shell.

> - Command line switches
> 	-d      -d      no-op vs. debug enable SIGQUIT/SIGTERM
> 	-p      -p      no-op vs. disable function import
> - startup file $home/lib/profile vs. $home/.rcrc
> - environment handling (system dependent)
> - different signal handlers (system dependent)

other comments:

> - $" vs. $^
> 	This seems like an arbitrary difference.
Byron's $^ preceeded td's $".  if you look at older versions of the
bell labs rc man page, it's not there.

> - pattern matching, word vs. list
> 	This fixes something noted as a bug in the Plan 9 man page.
i don't know what you mean by this comment.  i don't think Byron's
~ operator is any different from td's.

> - additional variables: history, ...
> 	Plan 9 may use history and not just not mention it in the man
i think it does.  i know it was a later addition to rc.

> - . -i (???)
> 	Duff's paper mentions this but the man page doesn't.
it's just undocumented, but it's there.

of the rest of the differences noted, the only ones which were
not upward compatible were

> - builtin flag
> - if not vs. else
> - $status

and, of course,
> - rfork vs. newpgrp (System dependent)
which is not really a shell difference.  (and, of course, the v10
version doesn't have rfork.)

Tom-- thanks for doing this list.  it was very informative to see
just what the differences were.  i was actually surprised by how
few differences there really were.

paul