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(elisp)Truenames

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Truenames
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   The "truename" of a file is the name that you get by following
symbolic links at all levels until none remain, then simplifying away
`.' and `..' appearing as name components.  This results in a sort of
canonical name for the file.  A file does not always have a unique
truename; the number of distinct truenames a file has is equal to the
number of hard links to the file.  However, truenames are useful
because they eliminate symbolic links as a cause of name variation.

 - Function: file-truename filename
     The function `file-truename' returns the truename of the file
     FILENAME.  The argument must be an absolute file name.

 - Function: file-chase-links filename
     This function follows symbolic links, starting with FILENAME,
     until it finds a file name which is not the name of a symbolic
     link.  Then it returns that file name.

   To illustrate the difference between `file-chase-links' and
`file-truename', suppose that `/usr/foo' is a symbolic link to the
directory `/home/foo', and `/home/foo/hello' is an ordinary file (or at
least, not a symbolic link) or nonexistent.  Then we would have:

     (file-chase-links "/usr/foo/hello")
          ;; This does not follow the links in the parent directories.
          => "/usr/foo/hello"
     (file-truename "/usr/foo/hello")
          ;; Assuming that `/home' is not a symbolic link.
          => "/home/foo/hello"

   Note: Buffer File Name, for related information.