Once a hard link is created, you can't really identify it as such (i.e. as anything other than a plain data file). You can figure out when a given file has more than one directory entry describing/pointing to it (checking the link count shown by "ls -l"), and you can figure out which directory entries point to the same file (checking for matching inode numbers with "ls -i"), but all entries have "equal status" -- the original directory entry is simply equivalent to (i.e. one of) the hard links. [emphasis added]

I have a feeling that we will be speaking at different facets of the problem at hand, but when I read your response, it says to me that the program will have a hard time identifying that a file is a hard link. I would probably make clear that the program as written would have a hard time identifying the duplicates.

The application could postprocess the F::F::D output and remove those files already hard linked by using the stat perl builtin. Given the device + inode + hash, you have a hardlink check.

I just had the impression, even if it was not intended, that a reader of this response could come away with the feeling that you needed to poll ls to determine if a file was a hardlink of another.

If you are interested in more detail on the hardlink stuff and how the underlying file system can implement them, see:

*My college reference books on this topic are at home, the revisions have changed (as well as the covers), and my memory is, umm, rusty :). So beware, these books may not be the ones I am thinking of.

--MidLifeXis

In reply to Re^2: Replace duplicate files with hardlinks by MidLifeXis
in thread Replace duplicate files with hardlinks by bruno

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