How do I force a single instance of a python app?

[Jeff Kunce]

> >The second instance of open("foo","w") does not fail.

> I can even open for append from two different instances of the same
> program and get interleaved output.

Yup. It can create some very interesting data files - I had to untangle one
once :-(

You can control that problem by using msvcrt.locking(), which
provides file locking facilities for windows.

  --Jeff