Sep 5, 2016 · Sep 28, 2016
diff --git a/console/lockable_trait.rst b/console/lockable_trait.rst
 Prevent Multiple Executions of a Console Command
 ================================================

 A simple but effective way to prevent multiple executions of the same command in
 a single server is to use **file locks**. The Filesystem component provides a
 :doc:`LockHandler </components/filesystem/lock_handler>` class that eases the
 creation and release of these locks.

 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\LockableTrait;

    class UpdateContentsCommand extends Command
    {
        use LockableTrait;

        // ...

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

                return 0;
            }

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

            // ...

            // if not released explicitly, Symfony releases the lock
            // automatically when the execution of the command ends
            $this->release();
        }
    }
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,38 @@
		Prevent Multiple Executions of a Console Command
		================================================

		A simple but effective way to prevent multiple executions of the same command in
		a single server is to use file locks. The Filesystem component provides a
		:doc:`LockHandler </components/filesystem/lock_handler>` class that eases the
		creation and release of these locks.

		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\LockableTrait;

		class UpdateContentsCommand extends Command
		{
		use LockableTrait;

		// ...

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

		return 0;
		}

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

		// ...

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