Optional notify-send

[savchenko]

Something along the lines of:

if [ "$DISPLAY" ] || [ "$WAYLAND_DISPLAY" ]; then
    if hash notify-send &> /dev/null; then
        # do things
    fi
fi

...with the caveat that it should go to the currently logged-in user.

Options:

1. Query said user and send directly from script
2. Drop data into a file within $TMPDIR and call from there

@oliver-machacik, want to give it a stab?