.NET CORE EnvironmentVariable

.NET CORE System variables SET
In System variables
e.g1：
Variable name: ASPNETCORE_ENVIRONMENT
Variable value:Development
e.g2:
Variable name: xxxDBConnectionString
Variable value:Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=DBNAME;User ID=usre;Password=123

.net core code :

Add Reference：Microsoft.Extensions.Configuration

string dbConnection = Environment.GetEnvironmentVariable("xxxDBConnectionString");
Console.WriteLine(dbConnection);

string ev = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
Console.WriteLine(ev);
Console.ReadKey();