Cron is a software utility for the Linux operating system that allows for the creation of scheduled task or "jobs". Simple cron time schedules are easy to create, though more complex scheduling can be tricky to remember.
To make it easy to make custom cron jobs I created in this crontab generator. To use it select your desired options from the tabs at the top and the equivalent cron expression will appear below. Just copy it and paste it into the crontab file in the appropriate location.