protected function getCliOutput($command)
    {
        $descriptorspec = array(
            0 => array('pipe', 'r'),
            1 => array('pipe', 'w'),
            2 => array('pipe', 'a')
        );

        $process = proc_open($command, $descriptorspec, $pipes);

        if (!is_resource($process)) {
            throw new RuntimeException(
                'Could not open a resource to the exiftool binary'
            );
        }

        $result = stream_get_contents($pipes[1]);
        fclose($pipes[0]);
        fclose($pipes[1]);
        fclose($pipes[2]);

        proc_close($process);

        return $result;
    }