To find out which version of Ubuntu you are running, run the following in terminal:
lsb_release command prints certain LSB (Linux Standard Base) and Distribution information.
No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 16.04.3 LTS Release: 16.04 Codename: xenial
lsb_release is part of a software package called the LSB core, which is not necessarily installed on your system by default.
To install it, run the command below
sudo apt-get update && sudo apt-get install lsb-core
The Linux Standard Base is a common runtime environment for third-party packages. The goal of the LSB is to make it easy to create binary packages that will run on any Linux distribution.