A UNIX command is used to schedule jobs to be executed at some time in the future, typically on a periodic or regular basis. When used as a daemon process, the cron runs continuously and executes in response to specified events. Cron jobs allow you to automate certain commands or scripts on your server to complete repetitive tasks automatically. A cron job allows you to run a certain command at the time set by the job.
For example, you could set a cron job to delete temporary files every week so that your disk space is not being used up by those files. This is a system process that runs in the background. Cron is allowed to be used by each user, controlled by “cron.allow” and “cron.deny” files. If the user is allowed to use cron, they can create a “crontab” (cron table) which is an ASCII file containing one or more commands to cron.