Reading Output from cmd asynchronously - vb.net

Question

I'm using this code:
Shared sb_OutputData As New StringBuilder()
Shared sb_ErrorData As New StringBuilder()
Shared proc As Process = Nothing
Private Sub cmd()
If proc IsNot Nothing Then
Exit Sub
End If
Dim info As New ProcessStartInfo("cmd.exe")
' Redirect the standard output of the process.
info.RedirectStandardOutput = True
info.RedirectStandardInput = True
info.RedirectStandardError = True
' Set UseShellExecute to false for redirection
info.UseShellExecute = False
proc = New Process
proc.StartInfo = info
' Set our event handler to asynchronously read the sort output.
AddHandler proc.OutputDataReceived, AddressOf proc_OutputDataReceived
AddHandler proc.ErrorDataReceived, AddressOf proc_ErrorDataReceived
proc.Start()
' Start the asynchronous read of the sort output stream. Note this line!
proc.BeginOutputReadLine()
proc.BeginErrorReadLine()
End Sub
Private Shared Sub proc_ErrorDataReceived(sender As Object, e As DataReceivedEventArgs)
'Console.WriteLine("Error data: {0}", e.Data)
sb_ErrorData.AppendLine(e.Data)
End Sub
Private Shared Sub proc_OutputDataReceived(sender As Object, e As DataReceivedEventArgs)
' Console.WriteLine("Output data: {0}", e.Data)
sb_OutputData.AppendLine(e.Data)
End Sub
Sub CmdWrite(arguments As String)
Dim writeStream As StreamWriter = proc.StandardInput
writeStream.WriteLine(arguments)
End Sub
It works exactly as I want, be able to retrieve cmd output and error data without closing it (and asynchronously), however, I'm not able to know when the command is finished executing. I'd like to know when it reaches the end of the stream for me to grab all the output and do something with it...
I've been searching for quite long, and can't find an answer to this.
Help please?

Answer 1

The stream is open is long as the command window is open. You can't tell when they stop or start. If the command you're running doesn't indicate its end with a unique/detectable pattern, you're stuck, unless you can edit the script you're running and insert a string - which you can't guarantee won't show in the normal output - in between the command calls.