You probably not only want to check file modification time but also make sure that the file is not currently in use being modified.
Usually it is sufficient to leave out files that have changed in the last minute or so. If you need to be absolutely sure that the file is not in use then use a call to *nx command lsof to list open files (needs root privs to work system wide).

In reply to Re^2: (OT) indexing pdf archive content in a multiuser environment- how do i know when the content changed? by varian
in thread (OT) indexing pdf archive content in a multiuser environment- how do i know when the content changed? by leocharre

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