Backend
What is Cron Job?
A task scheduled to run automatically at fixed times or intervals, defined with cron expressions on Unix-like systems.
Definition
A cron job is a command scheduled to run at recurring times, defined by a five-field expression like 0 3 * * * (daily at 03:00). The Unix cron daemon reads these from crontabs, while modern equivalents include Kubernetes CronJobs, AWS EventBridge schedules, and systemd timers. Typical uses are nightly backups, report generation, cache warming, and cleanup of expired records. Production cron jobs need overlap protection (locking so a slow run doesn't stack), failure alerting, and idempotent logic, since a missed or doubled execution should never corrupt data.