Simple Cronjob Example
Cron is a utility program for scheduling tasks, or cron jobs, in ubuntu and other linux based systems.
Cron is a daemon -- a background process. They are similar to Windows services.
The command crontab -e while logged in as root will open a contab for editting where you can place a cronjob.
This exmaple will delete the contents of a folder every 60 minutes:
*/60 * * * * find /usr/place/folder/* -delete
You can find a time cheatsheet here: https://onecompiler.com/cheatsheets/cron