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linuxunixinodehardlink

How to test in two paths are hard linkable?

I have file paths in one side and their new paths where I want to duplicate them.

How to test whether they can be simply hardlinked or they should be copied?

Solution

  • Step 1: Call link.

    Step 2: If it returns -1 with errno set to EXDEV, then make a copy.

    [update]

    In general, there is no portable (and reliable) way to answer this question. The closest you can get, I think, is to call statvfs for the source and destination and then compare the f_fsid fields of the statvfs structures.

    Unfortunately, POSIX does not guarantee anything in particular about the f_fsid field. This test should work on Linux unless maybe you are asking about NFS-mounted filesystems...