%ENV setting not exported to child process?

saintmike has asked for the wisdom of the Perl Monks concerning the following question:

Dear monks,

can you think of a reason why setting $ENV{foo} wouldn't be exported to a child process? Funny, I have two versions of perl-5.8.5, compiled with different threading options, which show different results:

/path1/perl (5.008005): Export OK
/path2/perl (5.008005): Export not OK
[download]

$ENV{foo} = "abc";
my $out = `echo \$foo`;

print "$^X ($]): Export ",
      $out ne "abc\n" ? "not " : "",
      "OK\n";
[download]

The difference between the two binaries is that one got linked to linuxthreads, while the other one uses pthreads, both on FreeBSD 4.x.

Weird, isn't it? Doesn't setting %ENV just translate to a setenv() at C-level?

Comment on %ENV setting not exported to child process? Select or Download Code

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Re: %ENV setting not exported to child process? by bluto (Curate) on Jan 13, 2006 at 00:20 UTC
Yeah it's wierd. FWIW, it's hard to tell from your example if the problem is really related to exporting (i.e. you aren't checking $?; you should print the contents of $out; you should probably use the fullpath to 'echo' and not rely on the shell built-in or your PATH).	[reply]
Re^2: %ENV setting not exported to child process? by saintmike (Vicar) on Jan 13, 2006 at 01:06 UTC
Just checked, it's not related to the full path to echo, and `$?` is `0`.	[reply] [d/l] [select]
Re: %ENV setting not exported to child process? by olivierp (Hermit) on Jan 13, 2006 at 15:31 UTC
I may be completely wrong, but isn't FreeBSD's pthreads actually the same process, so the child is actually seeing the same %ENV as perl itself ? HTH -- Olivier	[reply]
Re^2: %ENV setting not exported to child process? by saintmike (Vicar) on Jan 13, 2006 at 18:31 UTC
Well, but system() and `...` aren't running in a new thread, they're forking off a new process. How would that be related to the threading model? The only way I can see this happening is that perl doesn't use `setenv()` if a certain threading model is enabled, similar to what's been described here.	[reply] [d/l] [select]
Re: %ENV setting not exported to child process? by Argel (Prior) on Jan 16, 2006 at 22:01 UTC
I know when forking the child should inherit the environment of the parent. But does that rule apply to threads? -- Argel	[reply]