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 on systems that don't run 24 hours a day. anacron was originally conceived and implemented by Christian Schwarz in Perl, for the Unix operating system. It was later rewritten in C by Itai Tzur; maintainers have included Sean 'Shaleh' Perry and Pascal Hakim.