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Re: Re: how to tell if a file is still being modified

by bunnyman (Hermit)
on Sep 16, 2003 at 14:12 UTC ( #291823=note: print w/ replies, xml ) Need Help??


in reply to Re: how to tell if a file is still being modified
in thread how to tell if a file is still being modified

That scheme is inefficient and fragile. Why bother to read the entire file and calculate a hash on it, when checking the file size is a whole lot faster and for an FTP upload, is just as good?

It is fragile; imagine what would happen if the upload stalled for X+1 seconds and then resumed. If you make X large to try to avoid this, it makes the processing slower.

The permission bits scheme is better, if your system supports permission bits.


Comment on Re: Re: how to tell if a file is still being modified
Re: Re: Re: how to tell if a file is still being modified
by blue_cowdawg (Monsignor) on Sep 16, 2003 at 15:56 UTC

        That scheme is inefficient and fragile. Why bother to read the entire file and calculate a hash on it, when checking the file size is a whole lot faster and for an FTP upload, is just as good?
    If my scheme of checking a hash is fragile then checking file sizes is just as bad if not worse for the same reasons you stated mine was bad.

    As you say if the upload stalls for X+1 seconds then you are going to end up colliding with the upload when you act on what you assume is a finished file.

    I personally like the bit banging method much better but unfortuneatly that is UNIX-centric and is not portable to say Win32 and friends.

    As others have said there are no really clean and portable ways of doing this and YMMV no matter what method you use. Generating MD5 hashes worked for me and in a batch environment are not that expensive.


    Peter L. Berghold -- Unix Professional
    Peter at Berghold dot Net
       Dog trainer, dog agility exhibitor, brewer of fine Belgian style ales. Happiness is a warm, tired, contented dog curled up at your side and a good Belgian ale in your chalice.

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