1. We will create a .NET Core console application in Visual Studio 2017. Under Visual C# templates, select .NET Core and a Console App (.NET Core) project:

2. When you created your console application, the code will look as follows:

        using System;

        class Program
        {
          static void Main(string[] args)
          {
            Console.WriteLine("Hello World!");
          }
        }

3. Modify your code to look as follows:

        static void Main(string[] args)
        {
          Console.WriteLine("I can run on Windows, Linux and macOS");
          GetSystemInfo();
          Console.ReadLine();
        }

        private static void GetSystemInfo()
        {
          var osInfo = System.Runtime.InteropServices.RuntimeInformation.OSDescription;
          Console.WriteLine($"Current OS is: {osInfo}");
        }

4. The method GetSystemInfo() just returns the current operating system the console application currently runs on. The csproj file for my application looks as follows:

        <Project ToolsVersion="15.0"           xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
          <Import Project="$(MSBuildExtensionsPath)$(MSBuildToolsVersion)
            Microsoft.Common.props" />
            <PropertyGroup>
              <OutputType>Exe</OutputType>
              <TargetFramework>netcoreapp1.1</TargetFramework>
            </PropertyGroup>
            <ItemGroup>
              <Compile Include="***.cs" />
              <EmbeddedResource Include="***.resx" />
            </ItemGroup>
            <ItemGroup>
              <PackageReference Include="Microsoft.NETCore.App">
                <Version>1.1.0</Version>
              </PackageReference>
              <PackageReference Include="Microsoft.NET.Sdk">
                <Version>1.0.0-alpha-20161104-2</Version>
                <PrivateAssets>All</PrivateAssets>
              </PackageReference>
            </ItemGroup>
          <Import Project="$(MSBuildToolsPath)Microsoft.CSharp.targets" />
        </Project>

The <version> is defined as 1.1.0.