NukeViet\Core\Ips::nv_getenv PHP Method

    private function nv_getenv($key)
    {
        if (isset($_SERVER[$key])) {
            return $_SERVER[$key];
        } elseif (isset($_ENV[$key])) {
            return $_ENV[$key];
        } elseif (@getenv($key)) {
            return @getenv($key);
        } elseif (function_exists('apache_getenv') && apache_getenv($key, true)) {
            return apache_getenv($key, true);
        }
        return '';
    }