The other day I had to update a existing windows GUI application to enable it to be called via the command line. In order to do this, you need to add the following import to your .NET application (C# example shown):

          
            ///
<summary>
            ///
AttachConsole gives the ability for a GUI application to write to the console window
of the console from which it was started.
            ///
</summary> [System.Runtime.InteropServices.DllImport("kernel32.dll")] staticexternbool AttachConsole(uint dwProcessId); ///
<summary>///
Flag indicating that we should attach to parent console///
</summary>constuint ATTACH_PARENT_PROCESS = 0x0ffffffff; 
        

After adding these declarations to your main class, its a simple case of adapting your Main method to detect if you're running in console or GUI mode and acting accordingly. E.g:

            
              ///
<summary>
              ///
The main entry point for the application.
              ///
</summary> [STAThread] staticvoid Main(string[]
args) { //
Are we in console modebool isConsole = args.Length
> 0; if (!isConsole)
{ RunVisual(); } else { //
Attach to console AttachConsole(ATTACH_PARENT_PROCESS); //
Run console app RunConsole(args); } }