This article covers method to Upgrade Ubuntu 16.04 to Ubuntu 18.04. If you are still using Ubuntu version 16.04, you may want to consider updating to the latest Long Term Support release, version 18.04.
What does LTS or Long Term Support Release Mean?
A Long Term Support release or LTS release, means that Ubuntu will support the version for five years.
If you are running a production environment, you will likely want to use a Long-Term Support version of your preferred server operating system.
What is New in Ubuntu Version 18.04:
1. Depending on when you installed Ubuntu version 16.04, the Linux kernel used would have been anywhere from version 4.4 to 4.10. Version 18.04 uses Linux kernel 4.15 at launch.
2. Linux kernel 4.5 now includes new features like CPU controller for the cgroup v2 interface, AMD secure memory encryption support, the latest MD driver with software RAID enhancements, and improved power management for systems with SATA Link Power Management.
3. The new kernel also includes some Ubuntu-specific updates, Linux security module stacking support, and the signing of POWER host and NV kernels is now supported.
18.04 does not install Python 2 default, and it updated Python version 3 to version 3.6.
4. Apache updates to version 2.4.29 and supports HTTP/2.
5. Nginx updates to version 1.14.0.
6. PHP updates from version 7.1 to 7.2.
7. The ifupdown network manager is removed on new installs and is deprecated. netplan.io is the new network configuration manager.
8. OpenSSH now refuses to use RSA keys smaller than 1024 bits. This command can report the length of a key.
ssh-keygen -l -f /path/to/key.pub
32-bit PowerPC support has been dropped.
9. The Subuquity server installer brings live sessions and fast installs of Ubuntu Desktop to server users.
10. Ubuntu 18.04 ships with LXD system container manager version 3.0. Version 3.0 of LXD allows for clustering of LXD servers, adds support of NVIDIA run-time pass-through, and lxd-p2c is a new tool that turns existing systems into LXD containers.
To Upgrade Ubuntu from 16.04 to 18.04:
1. Create a backup of your environment.
2. Run the command below to update and upgrade the packages.
$ sudo apt-get update && sudo apt-get upgrade
3. To add the Update Manager to your server add command below to your terminal.
$ sudo apt install update-manager-core
4. Now that you have created a backup installed package updates and have the upgrade manager you are ready to upgrade Ubuntu.
$ sudo do-release-upgrade
5. To check what version of Ubuntu is currently installed use the command below.
$ lsb_release -a