at

Executes commands at a specified time. More information: https://man.archlinux.org/man/at.1.

Open an at prompt to create a new set of scheduled commands, press Ctrl + D to save and exit:

at {{hh:mm}}

Execute the commands and email the result using a local mailing program such as sendmail:

at {{hh:mm}} -m

Execute a script at the given time:

at {{hh:mm}} -f {{path/to/file}}

Display a system notification at 11pm on February 18th:

echo "notify-send '{{Wake up!}}'" | at {{11pm}} {{Feb 18}}