I think the various "nit-picky details" of using file locking like this may be a good reason to stick with the pid-file idea explained in the initial reply -- assuming of course that the goal is to make sure only one instance of a program is running on the same host where you would be trying to start a new instance.

If for some reason there are different hosts that share a given disk and might try to start instances of this process, but only one host at a time may run the one instance of the process, then you'd have to complicate the pid-file approach somewhat, and file locking might be easier/better overall (assuming it works reasonably well on your shared file system... YMMV).

In reply to Re^3: Abort if instance already running? by graff
in thread Abort if instance already running? by pileofrogs

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