Capture powershell output from C#

I am trying to run this C# code:

Runspace rs = RunspaceFactory.CreateRunspace();
rs.Open();
PowerShell ps = PowerShell.Create();
ps.Runspace = rs;
ps.AddScript("Write-Output Hello | Out-File -FilePath myfile.txt");
ps.Invoke();

myfile.txt should contain Hello but the file does not exist. How can i redirect powershell commands standard output (and errors) ?

Thanks

*** EDIT ***

I have understood the problem: The Invoke command is not a blocking-command. So when Invoke() has finished, my file.txt does not exist yet.

Is there a way to wait for powershelgl script ending ? Thanks

> I have understood the problem: The Invoke command is not a blocking-command. So when Invoke() has finished, my file.txt does not exist yet.

You've misunderstood the problem, Invoke() is a synchronous method.

You haven't specified a location in which to operate (eg. cd C:\some\path\ in the PowerShell script), so PowerShell will use the working directory of the hosting process as it's default location. The file will be written to the directory from which you launched your application, or the root of your user profile if you launched the application from the shell in Windows.

If you want to consume the output in your C# application, iterate over the return value from Invoke() instead:

Runspace rs = RunspaceFactory.CreateRunspace();
rs.Open();
PowerShell ps = PowerShell.Create();
ps.Runspace = rs;
ps.AddScript("Write-Output Hello");

foreach (var outputItem in ps.Invoke()) {
  if (ps.HadErrors) {
    Console.WriteLine("Errors encountered!")
    foreach (var errorRecord in ps.Streams.Error) {
      Console.WriteLine(errorRecord);
      Console.WriteLine(errorRecord.ScriptStackTrace);
    }
    break;
  }
  Console.WriteLine(outputItem.BaseObject); // this will print the string Hello
}