There will be times when you will want to schedule some task to automatically occur in the future. There are 2 solutions that are available that let’s you do this “at”, and “cron”. The “at” utility is designed for scheduling an adhoc job, e.g. perform a patch installation at 9pm on Sunday. Whereas the “cron” utility is designed for scheduling a job that needs to be repeated on a regular basis, e.g. take backups at 5am every morning.
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The next couple of lessons will cover both “cron” and “at”.
If you want to run a one-off job at some point in the future, then you need to use “at” command.
“at” is comprised of the atd service:
$ systemctl status atd atd.service - Job spooling tools Loaded: loaded (/usr/lib/systemd/system/atd.service; enabled) Active: active (running) since Wed 2015-05-06 20:32:44 BST; 1h 3min ago Main PID: 1344 (atd) CGroup: /system.slice/atd.service └─1344 /usr/sbin/atd -f May 06 20:32:44 localhost.localdomain systemd: Started Job spooling tools.
To create a new “at job”, you use the “at” command:
$ whatis at at (1) - queue, examine or delete jobs for later execution