1. update all your system software to the latest version available
$ sudo yum update
2. Verify if cronie package is installed
$ sudo rpm -q cronie
3. Install cronie package
$ sudo yum install cronie
4. Check if crond service is running
$ sudo systemctl status crond.service
5. Configure cron jobs
$ sudo cat /etc/crontab
6. Create cronjob for current user
$ sudo vi /var/spool/cron/iphuong
6. Restart the crond service
$ sudo systemctl restart crond.service