Cannot run cmd.exe through service. No commands appear to be working

Question

I am trying to call a very specific command, that I can call through cmd, using a service. I'm using a service because I want this command to run every single time I log in, so I inherit from ServiceBase.

class Program
{
    static void Main(string[] args)
    {
        ServiceBase.Run(new RestartService());
    }
}

public class RestartService : ServiceBase
{
    public RestartService()
    {
        CanHandleSessionChangeEvent = true;
    }

    protected override void OnStart(string[] args)
    {
        Log("Starting");
        base.OnStart(args);
    }

    protected override void OnSessionChange(SessionChangeDescription changeDescription)
    {

        Log($"Session was changed: {changeDescription.Reason}");

        if (changeDescription.Reason == SessionChangeReason.SessionLogon || changeDescription.Reason == SessionChangeReason.SessionUnlock)
        {
            Log("Logon/unlock detected");

            try
            {
                var psi = new ProcessStartInfo()
                {
                    FileName = "C:\\Windows\\system32\\cmd.exe",
                    Arguments = "/c msg %username% hello",
                    RedirectStandardError = true,
                    RedirectStandardOutput = true,
                    RedirectStandardInput = true,
                    UseShellExecute = false,
                    CreateNoWindow = true
                };

                var p = Process.Start(psi);

                string result = p.StandardOutput.ReadToEnd();

                Log(result);
            }
            catch (Exception e)
            {
                Log($"ERROR: {e}");
            }
        }

        base.OnSessionChange(changeDescription);
    }

    public static void Log(string logMessage)
    {
        using (StreamWriter w = File.AppendText("C:\\Users\\username\\Desktop\\log.txt"))
        {
            w.Write("\r\nLog Entry : ");
            w.WriteLine($"{DateTime.Now.ToLongTimeString()} {DateTime.Now.ToLongDateString()}");
            w.WriteLine("  :");
            w.WriteLine($"  :{logMessage}");
            w.WriteLine("-------------------------------");
        }
    }
}

I have also tried using:

[DllImport("msvcrt.dll")]
public static extern int system(string format);

and then calling system("msg %username% hello") but unfortunately that doesn't work either.

When I open the log.txt file, I can see this:

Log Entry : 12:29:44 PM Tuesday, September 15, 2020
  :
  :Session was changed SessionLock
-------------------------------

Log Entry : 12:29:45 PM Tuesday, September 15, 2020
  :
  :Session was changed SessionUnlock
-------------------------------

Log Entry : 12:29:45 PM Tuesday, September 15, 2020
  :
  :Logon/unlock detected
-------------------------------

Log Entry : 12:29:45 PM Tuesday, September 15, 2020
  :
  :
-------------------------------

So I lock the PC, unlock the PC, and then call cmd.exe /c msg %username% hello. However, the popup doesn't appear. No matter which command I try, it doesn't work.

I did go in and tick the "Allow service to interact with desktop" option, but that unfortunately didn't work either.

My local account using `sc create NAME BinPath=PATH` after running `dotnet publish -r win-x64 -c Release` — MortenMoulder, Sep 15 '20 at 10:48
afaik, `ServiceBase` is .NET FW specific, you've mentioned .NET Core cli. How does your project look like? — Pavel Anikhouski, Sep 15 '20 at 10:50
@PavelAnikhouski I've installed Microsoft.Windows.Compatibility (3.1.1). I'm using a regular .NET Core 3.1 console app — MortenMoulder, Sep 15 '20 at 10:53
for what you run *cmd.exe* ?! instead run *msg.exe* ? for what run *msg.exe* instead call *MessageBoxW* ? — RbMm, Sep 15 '20 at 10:54
@MortenMoulder - in any case you not need run cmd. this is 100% exactly. about another - what you try todo ? — RbMm, Sep 15 '20 at 10:58
@RbMm I am trying to call an .exe file with arguments when I log into my machine. — MortenMoulder, Sep 15 '20 at 11:02
and what problem in this ? as side note - i doubt that you need exec exe — RbMm, Sep 15 '20 at 11:03
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/221504/discussion-between-mortenmoulder-and-rbmm). — MortenMoulder, Sep 15 '20 at 11:05

Cannot run cmd.exe through service. No commands appear to be working

0 Answers0