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From: Giorgos Keramidas <keramida@ceid.upatras.gr>
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Subject: Re: setenv's broken case when value is nil
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In-Reply-To: <20100217175616.608022.FMU4029@unexploded-cow.prv.splode.com>
	(Noah Friedman's message of "Wed, 17 Feb 2010 17:56:16 -0800 (PST)")
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On Wed, 17 Feb 2010 17:56:16 -0800 (PST), Noah Friedman <noah@splode.com> wrote:
> lorentey@elte.hu changed env.el on 2007-08-29 to define setenv-internal and
> for setenv always to keep the variable name in process-environment, even if
> value is nil.  In other words, he removed the distinction between the empty
> string and nil, and therefore you can't remove variables from the
> environment using setenv anymore.
>
> Since all kinds of environment variables have meaning when they are
> defined, even if they are just set to the empty string, this is a screw.

It's not a very common usage pattern of environment variables, but you
are right.  There are all sorts of environment variables that work (for
some value of 'work') even if they are set to empty strings.