How to debug a C# command-line program

Question

I'm trying to build a command-line tool in C# with VS2010.

My question is: how do I debug this, like I would a winforms.
With winforms, I can step through the code, see the values at each individual step, etc...

Here however, the program only responds when I talk to it from the command line. I can't start a debug session, since that will first fully start the program. And due to the nature of the program, it will shut itself because there were no command-line arguments.

So no debugging can occur.

What do I need to do here?

EDIT: an example, since someone made a comment that makes me feel this explanation is needed.

C:\Path\To\File\file.exe -help

That is an example of how this program is adressed. The command, -help, is given in the same line that the program is started. In other words, I cannot first start the program, and then give it a command while it's running... because it won't be running anymore. It'll start, see that it had no arguments on startup, and because of that, shut down. That's how a command-line tool works.

1. Activate
2. Process possible arguments
3. Output results
4. Shut down automatically

It is not something that keeps running till you click the little x in the top right corner.

Answer 1

In the Project properties, under Debug, you can enter any Command Line Arguments you would like, and then run the app with F5, the debugger will be attached automatically.

Answer 2

You could add a call to Debugger.Launch to your startup code. Then you can compile, and start your app from the command line. You'll get a prompt asking you which debugger you want to attach (typically this will be a list of the different versions of Visual Studio you have installed), and away you go.

(But really, setting command-line parameters in Project properties > Debug tab is the better way to go most of the time. If that's not working for you, you should figure out why.)