Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!mcvax!ukc!dcl-cs!nott-cs!anw
From: anw@nott-cs.UUCP
Newsgroups: net.unix,net.unix-wizards
Subject: Re: question-- Bourne (and C) SHELL
Message-ID: <268@tuck.nott-cs.UUCP>
Date: Wed, 20-Aug-86 07:05:54 EDT
Article-I.D.: tuck.268
Posted: Wed Aug 20 07:05:54 1986
Date-Received: Thu, 21-Aug-86 04:11:29 EDT
References: <1751@ittatc.ATC.ITT.UUCP> <7028@utzoo.UUCP> <150@humming.UUCP> <6228@sun.uucp>
Reply-To: anw@nott-cs.UUCP (Dr A. N. Walker)
Organization: Maths Department, University of Nottingham, ENGLAND.
Lines: 27
Xref: mnetor net.unix:5247 net.unix-wizards:7622

In article <6228@sun.uucp> guy@sun.uucp (Guy Harris) writes:
>Try
>
>	if ls foo
>	then
>		:
>	else
>		echo foo does not exist
>	fi

Or you could try

	ls foo ||
	    echo foo does not exist

In complicated situations, "if ... then ... else ... fi" is clearer, but
where there is only one subsidiary command I think "&&" and "||" can tidy
up shell scripts quite a lot.  I often use (V7 with SV shell) something like

	[ -w foo ] || fault "can't write to foo"

where "fault" is a suitable function, such as

	fault () { echo $0: error, "$@" 1>&2; exit 1; }

						-- Andy Walker,
						     Maths Dept, Nottm Univ