Since cron runs jobs time-based, not interval-based, there’s no blindingly simple way to do it. However, although it’s a bit of a hack, you can set up multiple lines in crontab until you find the common denominator. Since you want a job to run every 72 minutes, it must execute at the following times:
- 00:00
- 01:12
- 02:24
- 03:36
- 04:48
- 06:00
- 07:12
- …
As you can see, the pattern repeats every 6 hours with 5 jobs. So, you will have 5 lines in your crontab:
0 0,6,12,18 * * * command 12 1,7,13,19 * * * command 24 2,8,14,20 * * * command 36 3,9,15,21 * * * command 48 4,10,16,22 * * * command
The other option, of course, is to create a wrapper daemon or shell script that executes and sleeps for the desired time until stopped.