Install the .NET SDK or the .NET Runtime on Ubuntu 

How to Install pgAdmin4 on Ubuntu 20.04/18.04/16.04?. This post has been written primarily to guide new users on installing pgAdmin 4 on Ubuntu 20.04/18.04/16.04. pgAdmin is a feature-rich and open source PostgreSQL administration and development platform that runs on Linux, Unix, Mac OS X, and Windows.

With pgAdmin you can manage PostgreSQL database servers, from version 9.2 using an intuitive and powerful web interface. We have guides on installing pgAdmin 4 on other platforms. 

PostgreSQL, or Postgres, is a relational database management system that provides an implementation of the SQL querying language. It’s standards-compliant and has many advanced features like reliable transactions and concurrency without read locks.

This guide demonstrates how to quickly get Postgres up and running on an Ubuntu 20.04 server, from installing PostgreSQL to setting up a new user and database. If you’d prefer a more in-depth tutorial on installing and managing a PostgreSQL database, see How To Install and Use PostgreSQL on Ubuntu 20.04. 

A chat about Ubuntu with Nathan Haines

Now you can update / upgrade your ubuntu old version from Ubuntu 15.10 wily werewolf to Ubuntu 16.04 Xenial Xerus (LTS) 

 Ubuntu is distributed on two types of images described below.

Desktop image
The desktop image allows you to try Ubuntu without changing your computer at all, and at your option to install it permanently later. This type of image is what most people will want to use. You will need at least 384MiB of RAM to install from this image.

Server install image
The server install image allows you to install Ubuntu permanently on a computer for use as a server. It will not install a graphical user interface. 

Guide for building C# apps on Ubuntu: NuGet packages