Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!lll-winken!uunet!cos!hqda-ai!jay
From: jay@hqda-ai.UUCP (Jay Heiser)
Newsgroups: comp.unix.questions
Subject: Re: Bourne Shell: Variable defined?
Keywords: Bourne shell, elementary question
Message-ID: <25130@hqda-ai.UUCP>
Date: 27 Mar 89 20:51:01 GMT
References: <1819@umbc3.UMBC.EDU>
Reply-To: jay@hqda-ai.ARPA (Jay Heiser)
Organization: CBSI@Washington, D.C.
Lines: 8


Take a look at 'test'  (type 'man test' for info).  
	[ -z "$foo" ] 	is true if the length of $foo is zero
	[ -n "$foo" ]	is true if the length of $foo is non-zero

I've found this to be more reliable than 
	[ $foo ] or X"$foo" = X

Jay G. Heiser