Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!wuarchive!mit-eddie!uw-beaver!fluke!dcd
From: dcd@tc.fluke.COM (David Dyck)
Newsgroups: comp.lang.perl
Subject: %ENV vs. exported environment.
Keywords: %ENV environment bug question
Message-ID: <1990Jul7.060454.12400@tc.fluke.COM>
Date: 7 Jul 90 06:04:54 GMT
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 80


I have been having unexpected results with %ENV.

Has anyone else noticed that undef %ENV,
will undefine %ENV in the perl environment, but it doesn't effect
the exported environment (to child system processes).

Adding new values to %ENV will export the new elements
to sub processes, but the old 'undef'ed values are still
exported also.

deleting specific values from %ENV seems to be the same
as setting that variable to "", instead of removing
it from the environment.

Only reset clears the exported environment.

Is this by design?
If so, why?

I invoked the following script with:
	env - F=1 G=2 /usr/local/perl p1

-- cut here for script p1 --
#!/usr/local/perl

$| = 1;

&printenv;

print "undef \%ENV;\n";
undef %ENV;

&printenv;

$ENV{'TERM'} = 'sun';

&printenv;

for $key (keys %ENV) {
	print "undef \$ENV\{$key\};\n";
	undef $ENV{$key};
}

&printenv;

print "reset 'E';\n";
reset 'E';

&printenv;

sub printenv
{
	&printperlenv;
	&printexportenv;
}

sub printperlenv
{
	local ($key, $value);
	print " -- perl %ENV --\n";
	while (($key,$value) = each %ENV) {
		print "$key=$value\n";
	}
#	print " --\n";
}

sub printexportenv
{
	print " -- exported environment --\n";
	system "/bin/env";
	print " --\n";
}
-- cut here

            David Dyck
    Domain: dcd@tc.fluke.COM
     Voice: +1 206 356 5807
      UUCP: {uunet,uw-beaver,decwrl,microsof,sun}!fluke!dcd
     Snail: John Fluke Mfg. Co. / P.O. Box 9090 / Everett WA  98206-9090 / USA