Our beloved cron(8) got very cool extensions! A ~ shortcut was added to let cron(8) pick a random (consistent) timer value. This is useful when you want to run something once an hour but don't care when exactly. Another extension is the -s option which helps prevent overlapping process launches when you have (unexpectedly) long-running processes.

The below example shows the power of this utility. I want rpki-client to run once an hour, but not start if its still running from the previous hour. The 24 minute comes from the ~ operator. If I'd restart the cron(8) daemon a new value will be picked.

This is very exciting!

job@anton ~$ doas crontab -l | grep rpki-client ~ * * * * -n -s rpki-client -v job@anton ~$ doas grep rpki-client /var/cron/log | tail -3 Apr 17 14:24:01 anton cron[76532]: (root) CMD (rpki-client -v) Apr 17 15:24:01 anton cron[59536]: (root) CMD (rpki-client -v) Apr 17 16:24:01 anton cron[97530]: (root) CMD (rpki-client -v)