The first time you run a job, it's helpful to do it manually. The more you do a job yourself, the more you learn about that job.
However, once you've run a job a few times, there's little more that you can learn about that job, as least in your current environment. At that point, it's best to automate the process. Linux already has a service that runs automated jobs on a regular basis, whether it be hourly, daily, weekly, or monthly.
Another reason why you want to automate tasks is so you can go home. With appropriate logs, you can make sure the job was properly executed when you return to work. Thus, you can configure a database job to run once per year, so you don't have to be at work on New Year's Eve.
Finally, when you administer a group of systems, the number of things you have to do can be overwhelming. Automation is often the only way to keep up with what you need to do. This is why you need to learn to manage the cron service.
It's easy to learn the workings of the cron service. Every Linux system includes numerous examples of cron jobs. The cron daemon wakes up every minute Linux is running, to see if there's a script scheduled to be run at that time.
Standard administrative jobs are run as scheduled in /etc/crontab. Red Hat and Debian configure this file in straightforward ways, with different command scripts for hourly, daily, weekly, and monthly jobs. The format starts with five time-based columns, followed by the user and the ...