How to upgrade from Ubuntu 14.04 LTS to 16.04 LTS Server

a)
$ sudo apt-get update

b)
$ sudo apt-get upgrade

c)
$ sudo apt-get dist-upgrade

d)
Reboot
$ sudo init 6



e)
$ sudo apt-get install update-manager-core

f)
set Prompt=lts
$ sudo vi /etc/update-manager/release-upgrades

g)
$ sudo do-release-upgrade -d

h)
Reboot
$ sudo init 6