Making sure script only runs once instance at a time.

[Paul Rubin]

"Tim Williams" <tim at tdw.net> writes:
> That's the same kind of principle as my posted snippet,  it doesn't
> rely on the file's presence or absence as such.  It only cares when
> the file exists *and* is held open by another process.    When the
> process exits,  the lock ends without needing to clean up.
> 
> It works on Windows, but that doesn't help the OP :)

Huh?  Fcntl is on linux.