Cron runs things in your crontab.
The format is something like
date parts, command, user.
Anacron is like cron, except that it uses timestamps to work out if a thing was supposed to run in the past, but didn't (e.g. the machine was off).
In Debian, anacron can be installed as an apt package which puts in a systemd service. It will have a default file
Debian has some folders /etc/cron/cron.hourly, cron.daily and cron.monthly.
Debian's default /etc/crontab attempts to run these, unless anacron is installed, in which case it will be caught be /etc/anacrontab instead.
at command lets you schedule one thing to happen at a particular time.
at now + 3 minutes at noon echo "notify-send 'oy'" > command.txt at now + 1 minute -f command.txt
atq lists the scheduled jobs
atrm n deletes job n in the schedule
batch is a version of
at which includes a load level parameter. This is useful for scheduling low priority jobs.