"Events and Messages : Reactive" - Automatically backup a file before it is to be overwritten

Event in zFTPServer:
OnUploadStart

Message in zFTPServer:
File status okay; about to open data connection.%EXECUTE("C:\Scripts\Backup.cmd" "%LOCAL_FILENAME%")%

Contents of file "C:\Scripts\Backup.cmd":
@echo off

rem Extract file information and remove quotes
set FILE=%1
for /f "useback tokens=*" %%a in ('%FILE%') do set FILE=%%~a

rem Perform the backup
copy /v /y "%FILE%" "%FILE%.bak" >NUL