How to lock a CLI script without leaving artefacts

YourSymfonyCommand.php

<?php
    /**
     * Lock files are no end of pain, especially ensuring they are correctly removed when things blow up.
     * This way there are never any artifacts left around, so nothing to clean up.
     */
    $socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
    if($socket === false) {
        throw new \Exception("Cannot create a socket, please check system configuration");
    }

    if(@socket_bind($socket, '127.0.0.1', self::LOCK_PORT) === false) {
        $output->writeln('<error>This command is already running</error>');
        return;
    }