Scheduling Cron Jobs Without Colliding Frequencies

Question

If I have several cron jobs that run:

1. Every minute
2. Every 5 minutes
3. Every 15 minutes
4. Every hour
5. At midnight

Then at exactly 00:00 I have 5 jobs running at the same time.

I want to add another job, that I simply need to run "once a day" -- regardless of when! In fact, I want the "when" to be during the least server-load time.

How can I do this?

Answer 1

One way to do so is this:

1. call the intended script once an hour.
2. On the first run of the script check for a temporary file called .runTime.
3. If such file exists
   1. Parse it and obtain the 24-hour format time from it.
   2. If the current hour equals the parsed time
      1. Delete the .runTime file and execute the intended script
   3. If it's a different hour -- abort execution
4. If there's no such file and the hour is 0 (midnight)
   1. compute a random hour between 0 and 23 and write it to the file