The crontab is used for running specific tasks on a regular interval. Linux crontab is similar to windows task schedules. Crontab is very useful for routine tasks like scheduling system scanning, daily backups etc. Crontab executes jobs automatically in the backend on a specified time and interval. In this tutorial, you will learn to uses of crontab with 20 useful examples for scheduling jobs. You can also use crontab for the tasks to run once in future only, but for any tasks to run once we recommends to use Linux at command.