How to demonstrate it? Write a script that tells you before tries to get an exclusive lock on the file, tells you after, and then holds it until it gets something from STDIN. Run two copies of the script repeatedly, and see if each blocks the other from thinking that it has a lock.

Oh, and always, always, always check the return value of flock. If you ever try out a new platform, you won't remember to run a complex manual test. But the return value from flock will indicate that it cannot get a lock right away.

In reply to Re: Flock() over NFS by Anonymous Monk
in thread Flock() over NFS by moseley

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