--- FileUtils.ln_s( old, new, *options )
  Options: force noop verbose

  old ؤΥܥå new ޤ
  new Ǥ¸ߤǥ쥯ȥǤȤ new/old ޤ
  new Ǥ¸ߤǥ쥯ȥǤʤʤ㳰 Errno::ENOTDIR ȯޤ
   force ץꤷȤ new 񤭤ޤ

    FileUtils.ln_s '/usr/bin/ruby', '/usr/local/bin/ruby'
    FileUtils.ln_s 'verylongsourcefilename.c', 'c', :force

--- FileUtils.ln_s( list, destdir, *options )
  Options: force noop verbose

  list[0]list[1] ĤؤΥܥå dir/list[0], dir/list[1] Ĥ
  ޤdestdir ǥ쥯ȥǤʤ㳰 Errno::ENOTDIR 
  ȯޤ
  list[0] ؤΥܥå destdir/list[0]list[1] ؤ
  ϡɥ destdir/list[1] Ĥޤ
  destdir ǥ쥯ȥǤʤ㳰 Errno::ENOTDIR ȯޤ

   FileUtils.ln_s Dir.glob('bin/*.rb'), '/home/aamine/bin'

