[Zope] running pg_dump on windows as external method

I am using zope on windows with an external python method to backup my database. I am struggling to run the following command: pg_dump.exe database > file I have tried using os.popen - no luck and also subprocess.Popen. eg: import subprocess         subprocess.Popen(['c:/dir/dir/pg_dump.exe','database','>','c:/dir/dir/output file']) The command string works perfectly in a terminal. Does anyone know how I should be doing this? I get no errors or traceback when I try the method through Zope. regards garry