File locking doesn't change what another application can or cannot do. Remember the caveats I mentioned. Renaming the file to something else will block another application from subsequently manipulating the file once you've begun your operation.

Don't think of file locking as "protect myself from the other application's meddling," but rather as "notify other applications of my meddling." If you want to protect your app from others, don't give the other app an opportunity to meddle at all.

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