Here's a Linux utility that I recently learned about: Anacron

Simliar to cron, it runs tasks on a periodic basis, but it will ensure the task runs when the computer is on.

My use case is that I want my backup repository integrity check to run once a week on my laptop, but when a cron @weekly task is going fire (midnight on Sunday) my laptop's going to be turned off. Anacron to the rescue!

So what I did is set up an anacron task to run my backup check script once a week, and then set up cron to run anacron every 10 minutes:

*/10 * * * *  /usr/sbin/anacron -s -t $HOME/.anacron/tab -S $HOME/.anacron/spool

And here's what my anacrontab looks like:

SHELL=/bin/bash
HOME=/home/nick

# period  delay  job-id  command
# # (days)  (min)
7 0 backup-check  $HOME/bin/backup.check