Question

I’m looking for an easy way to find the process tree (as shown by tools like Process Explorer), in C# or other .NET language. It would also be useful to find the command-line arguments of another process (the StartInfo on System.Diagnostics.Process seems invalid for process other than the current process).

I think these things can only be done by invoking the win32 api, but I’d be happy to be proved wrong.

Answer 1

If you don’t want to P/Invoke, you can grab the parent Id’s with a performance counter:

foreach (var p in Process.GetProcesses())
{
   var performanceCounter = new PerformanceCounter("Process", "Creating Process ID", p.ProcessName);
   var parent = GetProcessIdIfStillRunning((int)performanceCounter.RawValue);
   Console.WriteLine(" Process {0}(pid {1} was started by Process {2}(Pid {3})",
              p.ProcessName, p.Id, parent.ProcessName, parent.ProcessId );
}

//Below is helper stuff to deal with exceptions from 
//looking-up no-longer existing parent processes:

struct MyProcInfo
{
    public int ProcessId;
    public string ProcessName;
}

static MyProcInfo GetProcessIdIfStillRunning(int pid)
{
    try
    {
        var p = Process.GetProcessById(pid);
        return new MyProcInfo() { ProcessId = p.Id, ProcessName = p.ProcessName };
    }
    catch (ArgumentException)
    {
        return new MyProcInfo() { ProcessId = -1, ProcessName = "No-longer existant process" };
    }
}

now just put it into whatever tree structure want and you are done.