To leverage round-the-clock computing, tasks must run at all hours of the day. You could punctuate your sleep with waking interludes to log in and run this command or that command on dozens of machines, or you can enjoy your forty winks and turn the work over to the ubiquitous cron, a daemon, or perennial process, to execute commands on a schedule. From very often to every so often, cron happily minds the clock and runs jobs day or night. Learn how to configure and maintain cron, and discover just some of its many uses.

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