sudo apt install at
Enable the daemon service with:
sudo systemctl enable --now atd
Then jobs can be specified with absolute time, such as:
Type in your command, e.g.:
The jobs can also be specified relative to the current time:
at now +15 minutes
Finally, accept the jobs with ^D.
Display a list of commands to run with:
2 Sat Oct 20 16:00:00 2018 a roach-1
This will print all pending IDs. Remove a job by the ID with:
/var/spool/atd/ to see the jobs.
Automatically add a job for later, by setting the date, then using echo for the command.
t="$(date -d "2 minutes" +%R)" echo "fortune > ~/$FILE" | at "$t" watch cat $FILE
$t here outputs the day in minutes, but you could also do
t="$(date -d "2 days" +%m/%d/%Y)".