Why does RedirectStandardInput has no effect when ProcessStartInfo.CreateNoWindow is set to true?

Question

I use System.Diagnostics.Process to interact with a third party console application of which stdin/out/err have been redirected (the external program is written in C++ and I do not have no control over it).

ProcessStartInfo info = new ProcessStartInfo(fileName, arg); 
info.CreateNoWindow = false; // <- if true, stdin writes don't make it through
info.UseShellExecute = false;
info.RedirectStandardInput  = true;
info.RedirectStandardOutput = true;
info.RedirectStandardError  = true;

var proc = new Process() { StartInfo = info };
proc.OutputDataReceived += new DataReceivedEventHandler(myOutputHandler);
proc.ErrorDataReceived  += new DataReceivedEventHandler(myErrorHandler);
proc.Start();
proc.BeginOutputReadLine();
proc.BeginErrorReadLine();

Later...

proc.StandardInput.WriteLine("some-short-command");

Works ok in a test console app when info.CreateNoWindow = false; But has no effect when info.CreateNoWindow = true;

The output and error redirection work fine in both cases.

The above code is part of a class library defining custom actions for FinalBuilder. The described behavior can be observed from a test console application or running from within FinalBuilder desktop application.

Interestingly when run from a third context - FinalBuilder server - with same user and environment, StandardInput.WriteLine has no effect, whether info.CreateNoWindow is true or false.

What is going on?

Can I make stdin redirection work regardless of the execution context?

Answer 1

Not sure why but explicitly specifying the user here solves the problem:

proc.UserName = user;
proc.Domain= domain;
proc.Password= password;

Not very elegant but works for me and may help someone.