services.cron.systemCronJobs

A list of Cron jobs to be appended to the system-wide crontab. See the manual page for crontab for the expected format. If you want to get the results mailed you must setuid sendmail. See security.wrappers

If neither /var/cron/cron.deny nor /var/cron/cron.allow exist only root is allowed to have its own crontab file. The /var/cron/cron.deny file is created automatically for you, so every user can use a crontab.

Many nixos modules set systemCronJobs, so if you decide to disable vixie cron and enable another cron daemon, you may want it to get its system crontab based on systemCronJobs.