Crontab Ubuntu

https://help.ubuntu.com/community/CronHowto
https://www.digitalocean.com/community/articles/how-to-use-cron-to-automate-tasks-on-a-vps
https://www.digitalocean.com/community/articles/how-to-schedule-routine-tasks-with-cron-and-anacron-on-a-vps