Path: utzoo!utgpu!water!watmath!clyde!rutgers!husc6!bloom-beacon!gatech!purdue!i.cc.purdue.edu!j.cc.purdue.edu!pur-ee!iuvax!bsu-cs!dhesi
From: dhesi@bsu-cs.UUCP (Rahul Dhesi)
Newsgroups: comp.unix.questions
Subject: Re: csh, exit, &&, || (was Re: exit(-1), 0 is sometimes magic)
Keywords: exit, zero, shells
Message-ID: <1951@bsu-cs.UUCP>
Date: 25 Jan 88 16:34:46 GMT
References: <502@cresswell.quintus.UUCP> <6935@brl-smoke.ARPA> <1179@wjvax.UUCP> <10318@mimsy.UUCP> <574@cresswell.quintus.UUCP>
Reply-To: dhesi@bsu-cs.UUCP (Rahul Dhesi)
Organization: CS Dept, Ball St U, Muncie, Indiana
Lines: 17

In article <574@cresswell.quintus.UUCP> ok@quintus.UUCP (Richard A. O'Keefe) 
writes:
>But in *expressions*, && and || have the same meaning as in C.
>Which is the direct opposite of their interpretation with commands!

Actually, no.  The C-shell uniformly gives the following meanings
to these operators.

     &&     evaluate the next item iff the previous one succeeded
     ||     evaluate the next item iff the previous one failed

The meaning of "item" is defined by the grammar of expressions or
pipelines.  That success is represented by zero for processes and by
nonzero for expressions are UNIX and C conventions, not specifically a
csh convention.
-- 
Rahul Dhesi         UUCP:  <backbones>!{iuvax,pur-ee,uunet}!bsu-cs!dhesi