A cron job is a Linux command for scheduling a task to be executed sometime in the future. This is normally used to schedule a job that is executed periodically – for example, to send out a notice every morning. Some scripts, such as Drupal, WHMCS may require you to set up a cron job to perform certain functions.
For most cron jobs, there are three components present:
- The script that is to be called or executed.
- The command that executes the script on a reoccurring basis. This is typically set in the cPanel.
- The action or output of the script, which depends on what the script being called, does. Frequently, scripts called as a cron job modify files or databases; however they can perform other tasks that do not modify data on the server, like sending out email notifications.
Most scripts that require the use of a cron job will give you specific instructions on what needs to be setup, frequently giving examples.