For this example I have used Notepad (notepad.exe)
' Process.vbs
' VBScript to enforce single instance execution of an application
' Date : 5 Jan 2012
' Author : Nauman (Solveso)
' -------------------------------------------------------'
Option Explicit
Dim objWMIService, objProcess, colProcess, objShell
Dim strComputer, strList, strprocess, strprocess1
strComputer = "."
strprocess = "'notepad.exe'"
strprocess1 = "notepad.exe"
Set objWMIService = GetObject("winmgmts:" & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set colProcess = objWMIService.ExecQuery("Select * from Win32_Process Where Name = " & strprocess)
For Each objProcess in colProcess
strList = objProcess.Name
Next
if strlist = strprocess1 Then
wscript.echo "Aplication "& strprocess &" is already running, only one instance is allowed, please contact your administrator."
wscript.quit
end if
Set objShell = WScript.CreateObject ("WScript.shell")
objShell.run strprocess1
wscript.quit
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