This is only for those who have an excellent password at the login to keep others out, or for those who let no one else have access to their computer but themselves. If you share your computer don't use this.

First create a custom launcher in Cairo Dock, Docky, Awn, or a panel applet.

At command, enter this:     echo "xxxx1234" | sudo -S mintupdate

where xxxx1234 is Your password.

In other words this command will pipe your password to run Mintupdate and you won't have to enter it any more. So then, if my password was bill1234 (It isn't), the command would be: 

echo "bill1234" | sudo -S mintupdate   and that's it. From now on just click the launcher you created and Mintupdate will run.

I use it for synaptic too:  echo "bill1234" | sudo -S /usr/sbin/synaptic

and gparted:  echo "bill1234" | sudo -S gparted

This has saved me countless keystrokes in the last year. But remember, if you share your computer better to not use this shortcut.

Take care now.