Você quer algo como anacron :
anacron is a computer program that performs periodic command scheduling which is traditionally done by cron, but without assuming that the system is running continuously. Thus, it can be used to control the execution of daily, weekly, and monthly jobs (or anything with a period of n days) on systems that don't run 24 hours a day.
Disponível como pacotes na maioria das distribuições Linux. Há provavelmente também uma porta para o MS Windows ...