Cron jobs are jobs or tasks that run at regular intervals of time unlike the at command. For example, in office, my job is to keep all the detailed information of company employees that is confidential. To keep it secure and updated without any loss of information, I will have to take the backup of the latest data in external devices such as a hard disk or a flash drive. Depending upon the number of employees, I may have to take the backup on a minute, hour, daily or weekly basis. It's hard, tedious, and a waste of time to back up manually every time. By having the knowledge of how to schedule a cron job, it can be very easily achieved. A Cron job creation is frequently done by system administrators to schedule tasks that are to be performed at regular intervals, for example, taking the backup of a system, saving logs of each user who is logged in, monitoring and reporting the network usage of each user, performing system clean-up, scheduling system update, and so on.

Cron consists...