multiple instance on Unix

[David Bolen]

Mike Meyer <mwm at mired.org> writes:

> The (old) standard method for locking on Unix is to use a file. Open
> it in exclusive mode. Using os.open(<filename>, O_EXCL | O_RDONLY) (or
> O_WRONLY, or O_RDWR) should do the trick.

The oldest methods I tended to use still went the mkdir() route, since
that tends to be more reliable across NFS links (where the MKDIR
operation is still generally atomic, and doesn't involve NFS
machinations to support locking).  And if you're using a filesystem to
implement stuff like this you may not know if it's local or not.

-- David