http://ecmanaut.blogspot.com/2010/07/list-hardlinks-on-hfs-volumes.html

hardlinks.zsh

#! /bin/zsh

# get hfsdebug-lite at http://www.osxbook.com/software/hfsdebug/

parse-hfsdebug-path () { sed -n '/^  path /s/^.*://p' }
parse-hfsdebug-prev () { sed -n '/^  ownerID /s/^.* = \([0-9]*\).*/\1/p' }
parse-hfsdebug-next () { sed -n '/^  groupID /s/^.* = \([0-9]*\).*/\1/p' }

hardlinks () {
  hfsdebug=$(whence hfsdebug-lite || whence hfsdebug)
  stdout=$($hfsdebug "$@")

  parse-hfsdebug-path <<<$stdout
  prev=$(parse-hfsdebug-prev <<<$stdout)
  next=$(parse-hfsdebug-next <<<$stdout)

  while [[ "$prev" != "0" ]] ; do
    stdout=$($hfsdebug -c $prev)
    parse-hfsdebug-path <<<$stdout
    prev=$(parse-hfsdebug-prev <<<$stdout)
  done

  while [[ "$next" != "0" ]] ; do
    stdout=$($hfsdebug -c $next)
    parse-hfsdebug-path <<<$stdout
    next=$(parse-hfsdebug-next <<<$stdout)
  done
}

hardlinks "$@"