Run command in background from Symfony controller

runCommand.php

    /**
     * Call a command in background
     *
     * @param string $command
     * @param array  $arguments
     *
     * @return int
     */
    public function runCommand($command, $arguments = array(), $logName = 'tvdb.commands')
    {
        $root_dir = $this->get('kernel')->getRootDir();
        $cmd = sprintf('%s/console %s', $root_dir, $command);
        if (count($arguments) > 0) {
            $cmd = sprintf($cmd . ' %s', implode(' ', $arguments));
        }
        $cmd = sprintf("%s --env=%s >> %s 2>&1 & echo $!", $cmd, $this->get('kernel')->getEnvironment(), sprintf('%s/logs/%s.log', $root_dir, $logName));
        $process = new Process($cmd);
        $process->run();
        if (!$process->isSuccessful()) {
            throw new \RuntimeException($process->getErrorOutput());
        }

        $pid = $process->getOutput();

        return $pid;
    }