OpenBSD’s cron(8) daemon can randomize values (
~), and prevent multiple jobs
from running concurrently (
-s). Super useful additions that all cron
implementations should have had forever.
For example “0~30” will result in a random value between 0 and 30 inclusive. If either (or both) of the numbers on either side of the ‘~’ are omitted, the appropriate limit (low or high) for the field will be used.
0~30 1 * * * [-nsq] echo foo
These features are included in OpenBSD 6.7.