How to block running two instances of the same program?

Question

I need to make sure that user can run only one instance of my program at a time.
Which means, that I have to check programatically, whether the same program is already r

Answer 1

I scan the process list looking for the name of my apps executable with matching command line parameters then exit if there is a match.

My app can run more than once, but I don't want it running the same config file at the same time.

Obviously, this is Windows specific, but the same concept is pretty easy on any *NIX system even without specific libraries simply by opening the shell command 'ps -ef' or a variation and looking for your app.

   '*************************************************************************
   '     Sub: CheckForProcess()
   '  Author: Ron Savage
   '    Date: 10/31/2007
   '
   ' This routine checks for a running process of this app with the same
   ' command line parameters.
   '*************************************************************************
   Private Function CheckForProcess(ByVal processText As String) As Boolean
      Dim isRunning As Boolean = False
      Dim search As New ManagementObjectSearcher("SELECT * FROM Win32_process")
      Dim info As ManagementObject
      Dim procName As String = ""
      Dim procId As String = ""
      Dim procCommandLine As String = ""

      For Each info In search.Get()
         If (IsNothing(info.Properties("Name").Value)) Then procName = "NULL" Else procName = Split(info.Properties("Name").Value.ToString, ".")(0)
         If (IsNothing(info.Properties("ProcessId").Value)) Then procId = "NULL" Else procId = info.Properties("ProcessId").Value.ToString
         If (IsNothing(info.Properties("CommandLine").Value)) Then procCommandLine = "NULL" Else procCommandLine = info.Properties("CommandLine").Value.ToString

         If (Not procId.Equals(Me.processId) And procName.Equals(processName) And procCommandLine.Contains(processText)) Then
            isRunning = True
         End If
      Next

      Return (isRunning)
   End Function