What I did in the past was renaming the file. If you can rename it, it is not in use.

Particularly, when a process might reopen the file and append something, you have the advantage of having your file to work with and the process starts to write a new file.

Update:
Gellyfish is right, I did it only with MS/IBM/DEC-(nonUNIX) Systems.

In reply to Re: How to detect if file is in use? by Ben Win Lue
in thread How to detect if file is in use? by blazar

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