What are alternative methods to using a variable to prevent multiple instances of a PHP script from running simultaneously in a cron job?

To prevent multiple instances of a PHP script from running simultaneously in a cron job, you can use a lock file approach. This involves creating a lock file at the beginning of the script execution and checking for its existence before proceeding. If the lock file exists, the script should exit to prevent multiple instances from running at the same time. Once the script finishes executing, the lock file should be deleted. 

$lockFile = 'script.lock';

if (file_exists($lockFile)) {
    echo "Script is already running. Exiting.";
    exit;
}

file_put_contents($lockFile, '');

// Your script logic here

unlink($lockFile);

Keywords

locking file locking flock semaphore mutex

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