Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT") does not return the environment variable's value entered in the CLI

[Arash-Sabet]

Description

We have a dotnet 8.0 console application that is supposed to read an appsettings.{Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT")}.json file based on the value entered for the DOTNET_ENVIRONMENT environment variable. Unfortunately Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT") always returns null.

Reproduction Steps

Issue the following command:

 dotnet run -c Release -e DOTNET_ENVIRONMENT=Docker

Expected behavior

Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT") should return the value Docker per the reproduction step to be able to utilize appsettings.Docker.json file.

Actual behavior

Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT") returns null or empty.

Regression?

No response

Known Workarounds

No response

Configuration

.NET SDK:
Version: 8.0.203
Commit: 5e1ceea679
Workload version: 8.0.200-manifests.8cf8de6d

Runtime Environment:
OS Name: Windows
OS Version: 10.0.22631
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\8.0.203\

Other information

No response

[tommysor]

I don't think -e is a valid switch for dotnet run.
I also don't know of any way to pass an environment variable as a switch.
Possibly mixup with docker run that does have a switch -e, --env list Set environment variables

For dotnet run I believe you need to set the environment variable first.

Given a console application:

var myValue = Environment.GetEnvironmentVariable("MyVar");
Console.WriteLine($"MyVar: '{myValue}'");

Can be invoked with windows cmd:

set "MyVar=SomeValue" & dotnet run
MyVar: 'SomeValue'

[Arash-Sabet]

Thanks @tommysor
It worked well on Windows 11's command prompt but not on PowerShell. Is there something to consider in PS?

[tommysor]

It worked well on Windows 11's command prompt but not on PowerShell. Is there something to consider in PS?

Only that you need to use PowerShells way to set the environment variable and separate commands.
PowerShell:

$env:MyVar='OtherValue' ; dotnet run
MyVar: 'OtherValue'

For completeness, on Linux the environment variable can be set inline (without separating the commands and environment variable only set for the specific command)
Bash:

MyVar='BashValue' dotnet run
MyVar: 'BashValue'