I'm following one of the answers to Forced resolution of environment variables in order to create a small sub to manage incoming data containing environment variables, but I seem to get the error "use of uninitialized value in substitution iterator". From http://www.sitepoint.com/forums/printthread.php?threadid=114018, I can understand the problems around changing $_ inside a sub, and have adjusted my code accordingly (I think!), but I can't see what else I need to change to get the substitution to work. Anyway, here's the code... 
sub sub_env {
        my($in_string)=@_;
        $in_string =~ s/\$([A-Z0-9_]+)/$ENV{$1}/g;
        return $in_string;
}

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Thanks for your help.

In reply to use of uninitialized value in substitution iterator by furrypop

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