Hi all,

Is there to check if a file is used by other application or not before deleting it from the disk.

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Delete it using Carbon. Carbon doesn’t let you delete files that are in use.

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Nor does Cocoa. If you look at the documentation for NSFileManager, you’ll see its delete method (the exact name escapes me at the moment) returns a BOOL indicating success or failure.

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Huh? Just because it can fail doesn’t mean it will fail in the specific case of deleting a file that’s in use. The underlying UNIX system allows deletion of files that are still in use, and there is nothing in the NSFileManager docs to indicate that removeFileAtPath:handler: will fail in this case.

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My bad. I thought the documentation supported what I said, but going back and looking at it, I see that isn’t the case. Cheers!

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Why would you want to check if a file is in use before deleting it, anyway?

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man lsof

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There might be some circumstances where you’d want to check anyway, but it’s impossible to check this reliably, because there’s an inherent race condition. Between the time you check whether a file is in use and the time that you take action based on that decision, the file may become in use or vice versa. It’s generally better to use a method that tries to do whatever you’re interested in and returns an error code if the operation fails. This is how functions like open() work.

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There’s no inherent race condition if you use Carbon. Or if there is, it’s Apple’s bug, not yours. —-

I’m saying there’s a race condition if you first check if something’s in use, then do something based on that check. There’s no avoiding that. I’m suggesting that the poster use a BSD, or Carbon, or Cocoa, or whatever API that instead tries to do something and tells you if it fails.