C# Get real time powershell script output

Question

I have a C# function to run a remote Powershell script. I can see that the script is running and all is working well on the remote server, but I can't get any real time output from Powershell.
The ps1 script runs for a long time and has many outputs. The script is running rar.exe, so the output is supposed to be from rar.exe.

Here is the C# function:

public static bool RunBackupPowershell()
    {
        string password = "somepassword";
        string userName = "someuser";
        string shell = "http://schemas.microsoft.com/powershell/Microsoft.PowerShell";
        var target = new Uri("http://someserver:5985/wsman");
        SecureString securepassword = String2SecureString(password);
        PSCredential credential = new PSCredential(userName, securepassword);
        WSManConnectionInfo connectionInfo = new WSManConnectionInfo(target,shell,credential);
        connectionInfo.OpenTimeout = 4 * 60 * 1000;
        connectionInfo.OpenTimeout = 1 * 60 * 1000;
        connectionInfo.AuthenticationMechanism = AuthenticationMechanism.Credssp;

        Runspace remote = RunspaceFactory.CreateRunspace(connectionInfo);

        remote.Open();
        PowerShell PowerShellInstance = PowerShell.Create();
        PowerShellInstance.Runspace = remote;
        PowerShellInstance.AddScript("D:\\backup\\test.ps1");

        PSDataCollection<PSObject> outputCollection = new PSDataCollection<PSObject>();
        outputCollection.DataAdded += outputCollection_DataAdded;
        PowerShellInstance.Streams.Error.DataAdded += Error_DataAdded;
        IAsyncResult result = PowerShellInstance.BeginInvoke<PSObject, PSObject>(null, outputCollection);

        while (result.IsCompleted == false)
        {
            hubs.Clients.All.SendPowerShellResults("Waiting for pipeline to finish...");

            Thread.Sleep(1000);
        }

        hubs.Clients.All.SendPowerShellResults("Execution has stopped. The pipeline state: " + PowerShellInstance.InvocationStateInfo.State);

        foreach (PSObject outputItem in outputCollection)
        {
            hubs.Clients.All.SendPowerShellResults(outputItem);
        }
        return true;

    }

   static void outputCollection_DataAdded(object sender, DataAddedEventArgs e)
    {
        hubs.Clients.All.SendPowerShellResults("Object added to output."+e);
    }
    static void Error_DataAdded(object sender, DataAddedEventArgs e)
    {
        hubs.Clients.All.SendPowerShellResults("An error was written to the Error stream!"+e);
    }

The hubs.Clients.All.SendPowerShellResults function is a websocket and it is working - so I can receive data but it's not data from the Powershell output.

I would like to know what is going on here.

Answer 1

I had a similar issue, so created the example below to allow retrieving the results in real time using an Async Enumerable to get results from a PowerShell Pipeline.

https://gist.github.com/OnKey/83cf98e6adafe5a2b4aaf561b138087b

static async Task Main(string[] args)
        {
            var script = @"
For ($i=0; $i -le 5; $i++) {
    $i
    Start-Sleep -s 1 
}
";
            var p = new Program();
            await foreach (var item in p.PowerShellAsyncEnumerable(script))
            {
                Console.WriteLine(item);
            }
        }

        private IAsyncEnumerable<PSObject> PowerShellAsyncEnumerable(string script)
        {
            var rs = RunspaceFactory.CreateRunspace();
            rs.Open();
            var pipeline = rs.CreatePipeline();
            pipeline.Commands.AddScript(script);

            return new PsAsyncEnumerable(pipeline);
        }

        internal class PsAsyncEnumerable : IAsyncEnumerable<PSObject>
        {
            private readonly Pipeline pipe;
            public PsAsyncEnumerable(Pipeline pipe) => this.pipe = pipe;

            public IAsyncEnumerator<PSObject> GetAsyncEnumerator(CancellationToken cancellationToken = new()) 
                => new PsAsyncEnumerator(this.pipe);
        }

        internal class PsAsyncEnumerator : IAsyncEnumerator<PSObject>
        {
            private readonly Pipeline pipe;
            private TaskCompletionSource dataReady = new();

            public PsAsyncEnumerator(Pipeline pipe)
            {
                this.pipe = pipe;
                this.pipe.Output.DataReady += NotificationHandler;
                this.pipe.Error.DataReady += NotificationHandler;
                this.pipe.InvokeAsync();
            }
            
            private void NotificationHandler(object sender, EventArgs e)
            {
                this.dataReady.SetResult();
            }
            
            public ValueTask DisposeAsync()
            {
                this.pipe.Dispose();
                return ValueTask.CompletedTask;
            }

            public async ValueTask<bool> MoveNextAsync()
            {
                while (!this.pipe.Output.EndOfPipeline)
                {
                    var item = this.pipe.Output.NonBlockingRead(1).FirstOrDefault();
                    if (item != null)
                    {
                        this.Current = item;
                        return true;
                    }
                
                    await this.dataReady.Task;
                    this.dataReady = new TaskCompletionSource();
                }

                return false;
            }

            public PSObject Current { get; private set; }
        }

Answer 2

Check to see if this topic helps:

Get Powershell command's output when invoked through code

The streams holds a "PsDataCollection" type, each item containing our desired output. This types contains the "DateAdded" event. You can use DateAdded event to output the data as soon it is added!

https://learn.microsoft.com/en-us/dotnet/api/system.management.automation.psdatacollection-1.dataadded?view=pscore-6.2.0