Cron jobs

Cron is a utility for scheduling tasks to run on Linux and Unix systems. For example, you could run a script to scrape a website every Monday at 3 a.m. Or every third Monday. Or every four hours.

“What is Cron?” and other basic questions are answered clearly here.

Crontab Guru is a page that helps you write cron scheduling expressions correctly. Corntab is similar.

EasyCron” is a web-based cron manager. Starter plan: $12/month. Try it free for eight days.

Added 11/8/2019:

A clear 6-min. introduction to cron jobs