djangoproject

https://help.ubuntu.com/community/CronHowto #Cron is a system daemon used to #execute desired #tasks (in the background) at designated times. A crontab file is a simple text file containing a list of commands meant to be run at specified times. It is edited using the crontab command. The commands in the crontab file (and their run times) are checked by the cron daemon, which executes them in the system background.