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From: lmcl@ukc.UUCP (L.M.McLoughlin)
Newsgroups: net.unix
Subject: Re: Why do people use:  if [ "x$FOO" = "x" ] .... ?
Message-ID: <5046@ukc.UUCP>
Date: Fri, 19-Apr-85 15:48:59 EST
Article-I.D.: ukc.5046
Posted: Fri Apr 19 15:48:59 1985
Date-Received: Mon, 15-Apr-85 03:47:44 EST
References: <361@ho95b.UUCP>
Reply-To: lmcl@ukc.UUCP (L.McLoughlin)
Organization: Computing Laboratory, U of Kent at Canterbury, UK
Lines: 23

In article <361@ho95b.UUCP> wcs@ho95b.UUCP writes:
>
>	I've seen a lot of Bourne shell scripts that test for
>blank variables using the construct
>	if [ "x$FOO" = "x" ]
>
...
>	if [ "$FOO" = "" ]
>or
>	if [ -z "$FOO" ]

How about:
	case "$FOO"
	in
	'') echo ALL GONE;;
	*) echo Something here;;
	esac

Unless you have '[' built into your shell this is generally a lot faster
but maybe less readable.

I too used to use the "x$VAR" type tests and kicked myself when I saw the
case equivalent in the rn sources.