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From: rsalz@bbn.com (Richard Salz)
Newsgroups: comp.unix.questions
Subject: Re: Environment variables
Message-ID: <159@papaya.bbn.com>
Date: Wed, 26-Aug-87 00:18:16 EDT
Article-I.D.: papaya.159
Posted: Wed Aug 26 00:18:16 1987
Date-Received: Thu, 27-Aug-87 07:15:58 EDT
References: <626@unmvax.unm.edu> <2876@phri.UUCP>
Reply-To: rsalz@bbn.com (Richard Salz)
Organization: BBN Laboratories, Cambridge MA
Lines: 30
Summary: Use $?xxxx

The problem is in distinguishing between "set var value" and
"setenv var value" -- in most cases, the C shell hides any difference
between them -- $var will get the value of the "var" variable, be it
a shell variable or an environment variable.

With that caveat in mind:
	% if ( $?TERM ) echo TERM is set
	TERM is set
	% if ( $?FOO ) echo FOO is set
	% set FOO=yow
	% if ( $?FOO ) echo FOO is now set
	FOO is now set
	% if ( $?BAR ) echo BAR is set
	% setenv BAR value
	% if ( $?BAR ) echo BAR is now set
	BAR is now set


Roy's idea of using printenv is probably better, but his method will probably
cause quoting problems if you try to see if TERMCAP is set after using
tset(1); this seems to do it:
	% if ( `printenv TERMCAP | wc -l` == 1 ) echo TERMCAP is set
	TERMCAP is set
	% if ( `printenv CAP | wc -l` == 1 ) echo CAP is set
	%

Hope this helps,
	/r$
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