How to check when a powershell script is done running with Visual Studio - vb.net

Question

I am running a powershell script from within my app. I can start it and it completes without problem, but how do I check when its done? I need to do other actions, Only once its complete. Here is what I have, for a bit of reference:
Public Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
If requiredEnd = True And requiredPass = True And requiredPath = True And requiredSheet = True And requiredStart = True And requiredUser = True Then
For I = 0 To 7
objWriter.WriteLine(aryText(I))
Next
objWriter.Close()
Dim p As Process
p.Start("powershell", "-ExecutionPolicy ByPass -windowstyle hidden -file .\\Excel.ps1")
p.WaitForExit()
If p.HasExited = True Then
MsgBox("The Process Has Been Completed!")
Application.Exit()
End If
Else
If requiredEnd = False Or requiredPass = False Or requiredSheet = False Or requiredStart = False Or requiredUser = False Then
MessageBox.Show("You Have Missing Required Fields!")
Else
MessageBox.Show("That Is Not A Valid File!")
End If
End If
End Sub
Thanks for the help! Also, I am a beginner at this, so could you do a bit of an explanation on how it works if it isn't super straight forward? Thanks again.
Edit: I realize I forgot the key point: I can close the script, but I need to know if it exited successfully. So a way to check errors, basically.

Answer 1

Why not use a runspace to execute your powershell code in-process, instead of shelling out to an external application? Most of the code you see for this is in C# but you can of course do it in VB.net as well:
' create Powershell runspace
Dim MyRunSpace As Runspace = RunspaceFactory.CreateRunspace()
' open it
MyRunSpace.Open()
' create a pipeline and feed it the script text
Dim MyPipeline As Pipeline = MyRunSpace.CreatePipeline()
MyPipeline.Commands.AddScript(scriptText)
' add an extra command to transform the script output objects into nicely formatted strings
' remove this line to get the actual objects that the script returns. For example, the script
' "Get-Process" returns a collection of System.Diagnostics.Process instances.
MyPipeline.Commands.Add("Out-String")
' execute the script
Dim results As Collection(Of PSObject) = MyPipeline.Invoke()
' close the runspace
MyRunSpace.Close()
This code is taken from this MSDN blog which has a much more thorough and complete example application, but the basic idea here is to run the code natively in your application and then you can get the output any way you like to test for errors.