Sometimes you need to jot something down quickly to remember later. If you are on a Linux machine that uses systemd and journalctl, here is a quick way to do so:

quicknote () {
    echo "$@" | systemd-cat -t "note"

After you have defined this function, you can run something like this:

% quicknote This is a note that I want to remember.

And you can retrieve all of your notes with a command like this:

% journalctl -qt note
Sep 27 11:41:45 localhost note[22332]: This is test note 1
Sep 27 11:51:24 localhost note[25930]: This is test note 2
Sep 30 15:32:32 localhost note[1284]: This is test note 3
Oct 31 08:53:30 localhost note[18352]: This is test note 4

I find this to be a convenient way to take quick and dirty notes, and have a log of them available later.