I tried setenv. I modified the source and used this:

#!/usr/bin/perl

use strict;
use warnings;

setter( $ENV{'pathy'} = 'kuku' );
system("env");

sub setter {
    shift;
    while ( my ( $key, $value ) = splice @_, 0, 2 ) {
        $ENV{$key} = $value;
        }
        return;
}
[download]