private function getFilteredOutput($output, $command)
    {
        $output = str_replace(array("\r\n", "\r"), array("\n", ''), $output);

        $matches = array();
        if (preg_match($this->getOutputFilterRegex($command), $output, $matches) === 1) {
            $output = ltrim($matches[1]);
        }

        return $output;
    }