Wed 30 Mar 2016 — Thu 14 Jul 2016



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 crontab

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.


The at command lets you schedule one thing to happen at a particular time.

Some examples:

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.