Command Prompt Batchfile output to VB textbox - vb.net

Question

I have a number of batch files and I'm trying to wrap a GUI around them so they are easily available for some of my users all in one place.
At the moment, I've got 2 buttons and a Textbox. Each button calls the same batch file with a different working directory (though in production, the batch files will be different). At the moment, all it does is call 'DIR /A /B" to list a directory contents.
DIR /A /B
exit
I've got the following code: (Button 2 is identical, but with a different working directory)
Public Class Form1
Dim P As New Process
Dim SW As System.IO.StreamWriter
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
AddHandler P.OutputDataReceived, AddressOf DisplayOutput
P.StartInfo.CreateNoWindow() = True
P.StartInfo.UseShellExecute = False
P.StartInfo.WorkingDirectory = "C:\temp"
P.StartInfo.RedirectStandardInput = True
P.StartInfo.RedirectStandardOutput = True
P.StartInfo.RedirectStandardError = True
P.StartInfo.FileName = "c:\temp\dircmd.cmd"
P.Start()
P.SynchronizingObject = TextBox1
Try
P.BeginOutputReadLine()
TextBox1.Text = TextBox1.Text & vbCrLf & "Begin output" & vbCrLf
SW = P.StandardInput
SW.WriteLine()
MsgBox("WriteLine()")
SW.Dispose()
SW.Close()
MsgBox("StreamWriter Close")
P.WaitForExit()
P.CancelOutputRead()
P.Close()
MsgBox("Process Close")
Catch ex As Exception
MsgBox(ex.ToString())
End Try
End Sub
Private Sub DisplayOutput(ByVal sendingProcess As Object, ByVal output As DataReceivedEventArgs)
Textbox1.AppendText(output.Data() & vbCrLf)
End Sub
My problem is that I'm getting the output from each command, however its getting duplicated. First button, first time works fine. Second button works, but everything is listed twice. Going back to first button, everything is listed 3 times. I initially thought I needed to clear the StreamWriter buffer, but its not repeating old info, its just repeating new info and I'm not sure why.
Begin output
C:\temp>DIR /A /B
bob.txt
dircmd.cmd
LocationRouting.xml
TempFrogsareNOTCool.txt
Test.txt
test2.txt
Test3.txt
C:\temp>exit
Begin output 2
C:\>DIR /A /B
C:\>DIR /A /B
$Recycle.Bin
$Recycle.Bin
Config.Msi
Config.Msi
Documents and Settings
Documents and Settings
<snip>
C:\>exit
C:\>exit

Answer 1

Switch to using a Using construct to instantiate and dispose of the Process:
Option A:
Using P As Process = New Process
P.StartInfo.CreateNoWindow = True
P.StartInfo.UseShellExecute = False
P.StartInfo.WorkingDirectory = "C:\temp"
P.StartInfo.RedirectStandardInput = True
P.StartInfo.RedirectStandardOutput = True
P.StartInfo.RedirectStandardError = True
P.StartInfo.FileName = "c:\temp\dircmd.cmd"
P.Start()
Dim sOutput As String
Using oStreamReader As System.IO.StreamReader = P.StandardOutput
sOutput = oStreamReader.ReadToEnd()
End Using
OutputTextBox.Text = sOutput
P.Close()
End Using
Option B:
Private Sub TestDirOutputButton_Click(sender As System.Object, e As System.EventArgs) Handles TestDirOutputButton.Click
Using P As Process = New Process
AddHandler P.OutputDataReceived, AddressOf DisplayOutput
P.StartInfo.CreateNoWindow() = True
P.StartInfo.UseShellExecute = False
P.StartInfo.WorkingDirectory = "C:\temp"
P.StartInfo.RedirectStandardInput = True
P.StartInfo.RedirectStandardOutput = True
P.StartInfo.RedirectStandardError = True
P.StartInfo.FileName = "c:\temp\dircmd.cmd"
P.Start()
P.SynchronizingObject = OutputTextBox
Try
P.BeginOutputReadLine()
OutputTextBox.Text = OutputTextBox.Text & vbCrLf & "Begin output" & vbCrLf
SW = P.StandardInput
SW.WriteLine()
MsgBox("WriteLine()")
SW.Dispose()
SW.Close()
MsgBox("StreamWriter Close")
P.WaitForExit()
P.CancelOutputRead()
P.Close()
MsgBox("Process Close")
Catch ex As Exception
MsgBox(ex.ToString())
End Try
RemoveHandler P.OutputDataReceived, AddressOf DisplayOutput
End Using
End Sub