Fastest way to shutdown Ubuntu Mate 18.10
On Ubuntu, the command shutdown now
allows you to shut down the system without being a root user. For a one-click solution in Mate, associate this command to a panel launcher.
Beware not to click this by accident, because it will heavily disrupt your work. But then, you asked a one-click solution.
For a two-click solution, Mate might still might offer a "traditional" shut down button you can add to the panel next to the 'Gear' icon. If not, then you still can create your own two-click shut-down launcher for mate-session-save --shutdown-dialog
(gnome-session-quit --power-off
for Gnome users).
How about a keyboard shortcut?
Go to your keyboard settings - for me, that's Settings ⇒ Devices ⇒ Keyboard(not sure what it is in Mate, but should be quite similar), scroll down to the bottom and click the + to add a new
Then, name it, the command you'll want is sudo poweroff
(or sudo shutdown now
does the same thing, really) - and set it to whatever keyboard shortcut you want.
I recommend super+h, since that's not taken by default, and since super+l is lock- but obviously, you can do whatever you want.... including maping it to an F-key of your choice.
This works for me on Ubuntu 18.04
sudo poweroff
another option is to shutdown
shutdown –h 09:30
Power off the system.
--help Show this help
--halt Halt the machine
-p --poweroff Switch off the machine
--reboot Reboot the machine
-f --force Force immediate halt/power-off/reboot
-w --wtmp-only Don't halt/power-off/reboot, just write wtmp record
-d --no-wtmp Don't write wtmp record
--no-wall Don't send wall message before halt/power-off/reboot