How can you ensure a command runs repeatedly at set intervals?

Using cron jobs is the correct approach to ensure a command runs repeatedly at set intervals. Cron is a time-based job scheduler in Unix-like operating systems that allows users to schedule jobs (commands or scripts) to run automatically at specified times, dates, or intervals. This makes it ideal for processes that need to occur regularly, such as backups, system monitoring, or updates.

Cron jobs are defined in a special file called a crontab, where you can specify the exact timing details using a syntax that denotes minutes, hours, days of the month, months, and days of the week. Because of its nature, cron is well-suited for running scripts or commands at fixed intervals, whether that be every minute, hourly, daily, or on specific days of the week.

While other options exist—like at jobs, which are great for scheduling a one-time command, or systemd timers that can also handle periodic tasks, they don't offer the same straightforward recurring scheduling capabilities as cron jobs. Additionally, for loops can be used within shell scripts to create loops, but they're not as efficient or practical for scheduling tasks to run at predefined intervals without further complexity. Thus, for straightforward, regular execution of commands, cron jobs are the most effective choice.