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From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.questions
Subject: Re: Why does this shell program run under csh???
Message-ID: <7271@mimsy.UUCP>
Date: Tue, 30-Jun-87 21:42:00 EDT
Article-I.D.: mimsy.7271
Posted: Tue Jun 30 21:42:00 1987
Date-Received: Thu, 2-Jul-87 00:40:19 EDT
References: <8030@brl-adm.ARPA>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 23

In article <8030@brl-adm.ARPA> PAAAAAR%CALSTATE.BITNET@wiscvm.wisc.EDU writes:
>If there was a point at which the trouble could have been avoided it was
>during the design of the C shell's syntax. Then would have been a time
>to include a piece of upward compatability.

As others have mentioned, the C shell was generally available before
the Bourne shell.  The shells were experimental, and not something for
which compatibility was desired.

[later:]
>Again the General Principle for system designers is that of MNC:
>      MINIMUM  NECESARY   CHANGE
>(Credit: Asimov, "The End of Eternity").

Actually, MNC is a good general principle for those fixing bugs.
For designers of new systems, MNC is quite wrong.  If something is
botched, making it just barely useful is useful, but better is
fixing it entirely, whether the result is compatible or not.  If
it can be fixed entirely, *and* still compatible---via a compatibility
library, say---that is even better, but that is not really required.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	seismo!mimsy!chris