private function findinvirtual($pattern)
    {
        $result = array();
        $virtual = null;

        if ($this->file)
            $virtual = file($this->file);

        if (empty($virtual))
            return $result;

        // check each line for matches
        foreach ($virtual as $line) {
            $line = trim($line);
            if (empty($line) || $line[0]=='#')
                continue;

            if (preg_match($pattern, $line))
                $result[] = $line;
        }

        return $result;
    }