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From: maart@cs.vu.nl (Maarten Litmaath)
Newsgroups: comp.unix.questions
Subject: Re^2: Bourne Shell: Variable defined?
Keywords: Bourne shell, elementary question
Message-ID: <2202@solo1.cs.vu.nl>
Date: 22 Mar 89 18:13:46 GMT
References: <1819@umbc3.UMBC.EDU> <9899@smoke.BRL.MIL>
Organization: V.U. Informatica, Amsterdam, the Netherlands
Lines: 13

gwyn@smoke.BRL.MIL (Doug Gwyn ) writes:
\In article <1819@umbc3.UMBC.EDU> rostamia@umbc3.UMBC.EDU (Rouben Rostamian) writes:
\>In C Shell the variable $?foo returns true or false (0 of 1, really)
\>depending on whether or not the variable "foo" has been already defined.

\	if [ X"$foo" = X ]
\	then	:	# doesn't exist or is an empty string

The question was: "Has it been defined?"
Ergo, if $foo is an empty string, it IS defined and your test fails.
-- 
 Modeless editors and strong typing:   |Maarten Litmaath @ VU Amsterdam:
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