You have multiple options:

1. Debugger.Launch This is a function which will pop up a window where you can attach a Visual Studio Debugger. See: Debugger.Launch. This has one theoretical downside (which does not apply to you) it is only usable in Visual Studio and not for example in Rider as the API is not open. (But you when this window pops up you could attach Rider to the process)

2. "Wait" the first seconds in your program You could just pass an argument to your cli which indicates it should wait x seconds so that you can attach your Debugger.

public static void Main(string[] args)
{
    if(args[0] == "waitfordebugger")
    {
        Thread.Sleep(10000); // Wait 10 Seconds
    }

    // Do stuff here

You then call your program like this: dotnet run -- waitfordebugger

Unfortunately, this is going to be a very painful experience. There's no real command line debugger available for .NET Core.

However, CoreCLR developers use a plugin for lldb (on *nix) that teaches lldb about a number of commands that it can use to help debug .NET code.

Essentially:

lldb /path/to/dotnet/dotnet
plugin load /path/to/dotnet/shared/Microsoft.NETCore.App/*/libsosplugin.so
b SystemNative_ReceiveMessage
r run
clrstack

Further documentation:

• A tutorial: https://blogs.msdn.microsoft.com/premier_developer/2017/05/02/debugging-net-core-with-sos-everywhere/
• General setup instructions: https://github.com/dotnet/coreclr/blob/master/Documentation/building/debugging-instructions.md
• List of commands: https://github.com/dotnet/coreclr/blob/master/src/ToolBox/SOS/Strike/sosdocsunix.txt

If you start using it, you will quickly realize how painful this is. It's almost worth using VS/Rider/VSCode just for the debugger, sadly.