Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!uhccux!munnari.oz.au!cs.mu.oz.au!ok
From: ok@cs.mu.oz.au (Richard O'Keefe)
Newsgroups: comp.unix.questions
Subject: Re: How is && supposed to work in csh?
Message-ID: <2487@munnari.oz.au>
Date: 21 Oct 89 09:45:12 GMT
References: <89293.143521BACON@MTUS5.BITNET>
Sender: news@cs.mu.oz.au
Lines: 35

In article <89293.143521BACON@MTUS5.BITNET>, BACON@MTUS5.BITNET (Jeffery Bacon) writes:
> if ( -f /bin/sun4 ) /bin/sun4 && set arch=sun4 && goto gotarch
> if ( -f /bin/sun4c ) /bin/sun4c && set arch=sun4 && goto gotarch
> if ( -f /bin/sun3 ) /bin/sun3 && set arch=sun3 && goto gotarch
> if ( -f /bin/sun3x ) /bin/sun3x && set arch=sun3 && goto gotarch
> gotarch:

The csh(1) manual page says about
	if (expr) command
that "command must be a simple command, not a pipeline, a command
list, or a parenthesized command list."  One of the possible cases
for a pipeline is a sequence of commands separated by "&&".


A simpler scheme would be to do
	if      (-f /bin/sun4  && { /bin/sun4  }) then
	    set arch=sun4
	else if (-f /bin/sun4c && { /bin/sun4c }) then
	    set arch=sun4
	else if (-f /bin/sun3  && { /bin/sun3  }) then
	    set arch=sun3
	else if (-f /bin/sun3c && { /bin/sun3c }) then
	    set arch=sun3
	else
	    echo "Unable to determine architecture type"
	    exit 1
	endif

I find that it is generally better to write scripts using the Bourne shell
(sh) than the C shell (csh):  the sh language has rather fewer gotchas.  It
is also easier to do some things.  For example, I would really like the
error message to come out on stderr rather than stdout.  In sh it's easy:
	echo "Unable to determine architecture type" >&2
Given that you are going to try running up to four programs /bin/sun{3,4}{,c}
anyway, it seems odd to boggle at using the /bin/arch script to do it.