As far as I know Ubuntu does not have a built-in reminder application. Surely there are some third-party applications that do the job well, but I didn't want to install extra packages etc.
So, I tried to build mine!
This reminder is based on at(1) command, that allows you to run a
command at specified time.
In case it has not been installed on your system, just install it via:
at reads commands from standard input, so it is handy in case where we need an one-liner. For example the above command
starts Firefox after one minute. You can find more examples in the following link.
So, we found a
way to schedule one-time jobs but how are going to be notified?
notify-send to the rescue. This simple program sends notifications to the user via command line. For example the following
shows this notification on the desktop!
Notifications are fully customizable: You can set summary, body or add an image to your notification. Just man notify-send for more information.
The name as well as the image of the pop-up window are from the infamous "Impossible Mission" game in Commodore 64.