523  vim Makefile
  524  make clean; make
  525  vim Makefile
  526  make 
  527  vim Makefile
  528  ls
  529  cd .
  530  cd ..
  531  ls
  532  rm -rf xv6_rpi_port
  533  ls
  534  pwd
  535  cd xv6-rpi
  536  ls
  537  ls
  538  ls