• Certain actions must be performed periodically when utilising a UNIX-based operating system. It takes a long time and is inefficient to do things manually every time. UNIX has task schedulers built in to help with this problem. These task schedulers work in the same way as a smart alarm clock. The operating system will conduct the predetermined task when the alarm goes off.
• Cron daemon (default task scheduler) and at are two basic but powerful tools that come with Linux (more suitable for one-time task scheduling).

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