Prevent Running the Same Console Command Multiple Times

You can use locks to prevent the same command from running multiple times on the same server. The :doc:`Lock component </components/lock>` provides multiple classes to create locks based on the filesystem (:ref:`FlockStore <lock-store-flock>`), shared memory (:ref:`SemaphoreStore <lock-store-semaphore>`) and even databases and Redis servers.

In addition, the Console component provides a PHP trait called LockableTrait that adds two convenient methods to lock and release commands:

// ...
use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Command\LockableTrait;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;

class UpdateContentsCommand extends Command
{
    use LockableTrait;

    // ...

    protected function execute(InputInterface $input, OutputInterface $output): int
    {
        if (!$this->lock()) {
            $output->writeln('The command is already running in another process.');

            return Command::SUCCESS;
        }

        // If you prefer to wait until the lock is released, use this:
        // $this->lock(null, true);

        // ...

        // if not released explicitly, Symfony releases the lock
        // automatically when the execution of the command ends
        $this->release();

        return Command::SUCCESS;
    }
}

.. versionadded:: 5.1

    The ``Command::SUCCESS`` constant was introduced in Symfony 5.1.