There are three ways to schedule commands in Ubuntu, all of which work in different ways. The first is the
at command, which specifies a command to run at a specific time and date relative to today. The second is the
batch command, which is actually a script that redirects you to the
at command with some extra options set so your command runs when the system is quiet. The last option is the
cron daemon, which is the Linux way of executing tasks at a given time.