How can I set cron to run certain commands every one and a half hours?

Question

How can I set cron to run certain commands every one and a half hours?

Answer 1

You could do it with two crontab entries. Each runs every three hours and they are offset by 90 minutes something like this:

0 0,3,6,9,12,15,18,21 * * *

30 1,4,7,10,13,16,19,22 * * *