I’m writing an application that can be started either as a standard WinForms app or in unattended mode from the command-line. The application was built using the VS 2k5 standard WinForms template.
When the application is executed from the command-line, I want it to output information that can be captured by the script executing the application. When I do this directly from Console.WriteLine(), the output does not appear, although it can be captured by piping to a file.
On the other hand, I can force the application to pop up a second console by doing a P/Invoke on AllocConsole() from kernel32. This is not what I want, though. I want the output to appear in the same window the application was called from.
This is the salient code that allows me to pop up a console from the command line:
<STAThread()> Public Shared Sub Main() If My.Application.CommandLineArgs.Count = 0 Then Dim frm As New ISECMMParamUtilForm() frm.ShowDialog() Else Try ConsoleControl.AllocConsole() Dim exMan As New UnattendedExecutionManager(ConvertArgs()) IsInConsoleMode = True OutputMessage('Application started.') If Not exMan.SetSettings() Then OutputMessage('Execution failed.') End If Catch ex As Exception Console.WriteLine(ex.ToString()) Finally ConsoleControl.FreeConsole() End Try End If End Sub Public Shared Sub OutputMessage(ByVal msg As String, Optional ByVal isError As Boolean = False) Trace.WriteLine(msg) If IsInConsoleMode Then Console.WriteLine(msg) End If If isError Then EventLog.WriteEntry('ISE CMM Param Util', msg, EventLogEntryType.Error) Else EventLog.WriteEntry('ISE CMM Param Util', msg, EventLogEntryType.Information) End If End Sub
Update 1:
As said in Michael Burr answer, Raymond Chen recently posted a short article about this. I am happy to see that my guess was not totally wrong.
Update 0:
Disclaimer: This ‘answer’ is mostly speculation. I post it only because enough time has passed to establish that not many people have the answer to what look like a fundamental question.
I think that the ‘decision’ if the application is gui or console is made at compile time and not at runtime. So if you compile your application as gui application, even if you don’t display the gui, its still a gui application and doesn’t have console. If you choose to compile it as console application then at minimum you will have a console windows flashing before moving to gui ‘mode’. And I don’t know if it is possible in managed code.
The problem is fundamental, I think, Because a console application has to take ‘control’ of the calling console application. And it has to do so before the code of the child application is running.