private function getCommand()
    {
        // Prefix command with exec on non Windows systems to ensure that we
        // receive the correct pid.
        // See http://php.net/manual/en/function.proc-get-status.php#93382
        $commandPrefix = $this->isWindows() ? '' : 'exec ';
        return $commandPrefix . escapeshellarg(realpath($this->config['path'])) . ' ' . $this->getCommandParameters();
    }