Changing parent process environment variable

[tcf22]

I don't even know if this is possible, but hopefully it is. This script needs to run on Win32 and Win64. I need to run a perl script from a shell and change the environment of the shell.

I tried

system("set VAR=5");

but that has no effect on the parent as I would suspect.

I have also tried using Win32::Process::Info to get the parent PID(hopefully there is an easier way).

use Win32::Process::Info;

my $pi = Win32::Process::Info->new ();
my %subs = $pi->Subprocesses();

my $ParentPID;
foreach(keys %subs)
{
    foreach my $pid(@{$subs{$_}})
    {
        if( $pid == $$ )
        {
            print "Parent PID is $_\n";
            $ParentPID = $_;
        }
    }
}

my @info = $pi->GetProcInfo($ParentPID);

use Data::Dumper;
print Dumper \@info;

but I don't know what to do with the parent PID to chenge the environment.

Thanks.