shell-w7: Upload the missed script

some changes for the original homework:
    1.add the step to handle the soft link file(line9-10)
    2.all the files in result sort accroding to the size(line25-27)
     (the original version is not sorted by size as a little
      misunderstanding the "find |xargs cat" will handle the
      file one by one...the fact is all the file will cat at
      the sametime)

     (note: the time of script run is 4s longer than the original version
            for testing /var dir. but all the requirements of the homework
            have reached).

Signed-off-by: rxf1986 <rxf1986@1603459400.qq.com>