revpath  -  generate a relative path that can be used to undo a change-


   revpath path


   The revpath program prints out a relative path that is the  ``reverse''
   or  ``inverse''  of  path.   Start with two directories top and bottom,
   with the latter below the former, and path is the  location  of  bottom
   relative to top.  The output of revpath is the location of top relative
   to bottom.  The resulting path contains a trailing `/'  character  when
   the result is non-trivial.  If path is equivalent to `.', the resulting
   output is empty.  If  path  is  invalid  in  some  way  (e.g.,  doesn't
   represent  the  path to a subdirectory) the output is also empty and no
   error messages are ever generated.


   There are no diagnostics.  Error conditions are silently  ignored,  and
   the exit status is always 0.


   It  isn't  possible  to  reverse arbitrary relative paths.  If any path
   element between the two end points of path  is  a  symbolic  link,  the
   results will probably be incorrect.


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