What might cause cron jobs to occasionally not run or complete?

Question

In my crontab, I have set MAILTO and a bunch of cron jobs (5-10 jobs).

These cron jobs usually run fine and I get emails for them. Most of these jobs consistently run as expected. Emails and filesystem results verify this.

Two of these jobs sometimes don't run, or don't complete as expected. I receive no email and the filesystem doesn't show any results.

What could cause this? The system didn't reboot, so it should have been running at the scheduled times. At least, how come there was no email?

If it makes any difference, this is on Fedora 15 Linux.

Answer 1

I'm just guessing here, but depending on the job, they could hang, and keep running without completion, until you manually restart/kill them.

It is hard to tell without knowing what an example cron job is, or what their function is.

Typically if you log something properly it will give you output, either via mail or /var/log/