The software utility cron (or cron job) is a time-based job scheduler in Unix-like operating systems.
A crontab file defines the cron jobs of a user or system. You can edit it by running crontab -e.
Each line of a crontab represents a job. This is the schema:
# ┌───────────── minute (0 - 59) # │ ┌───────────── hour (0 - 23) # │ │ ┌───────────── day of the month (1 - 31) # │ │ │ ┌───────────── month (1 - 12) # │ │ │ │ ┌───────────── day of the week (0 - 6) (Sunday to Saturday) # │ │ │ │ │ # * * * * * <command to execute>
If a * is at one position, it is unrestricted. If minute is *, it will run every minute (but not necessarily every hour or day).
You can also specify */n to run every n-th interval. Setting hour to */5 it will run every five hours.