Deploying rEFInd on Ubuntu 16.04 LTS with secure boot enabled
For these dual-booting Ubuntu 16.04 with an alternate operating system in UEFI boot mode, it may often be necessary to use a third-party boot manager such as rEFInd, as it's significantly superior to grub2's on UEFI-capable systems.
This write-up assumes that:
(a). The user is running a current Ubuntu 16.04LTS operating system installation (preferably on a dual-boot system)