TYPO3 Core

An alternative to executing the scheduler via cron might be to execute it using the "at"-daemon. This allows the scheduler to be highly flexible when to be invoked next. Also no access is needed to be able to create/modify a cronjob.

1) Determine when next task is to be executed.
2) If next task is 60min from now no need to execute scheduler every 5min or so.
3) If last regular job is disabled, don't execute scheduler-job through atd anymore.
4) If interval for jobs is changed, reschedule next execution through atd.
5) Upon running scheduler automatically schedule next run for itself.

Please note that using the at-daemon needs to be allowed for this to work and the webserver-user needs a valid shell. However if we assume cron is available on a system then it might also be equally likely for at to be available :-)