Register Microsoft key and feed
Before installing .NET, you'll need to register the Microsoft key, register the product repository, and install required dependencies. This only needs to be done once per machine.
Open a command prompt and run the following commands:
wget -q https://packages.microsoft.com/config/ubuntu/18.04/packages-microsoft-prod.deb
sudo dpkg -i packages-microsoft-prod.deb
Install the .NET SDK
Update the products available for installation, then install the .NET SDK.
In your command prompt, run the following commands:
sudo add-apt-repository universe
sudo apt-get install apt-transport-https
sudo apt-get update
sudo apt-get install dotnet-sdk-2.2