% mkdir -p {0..3}/{0..3} % find . -type d . ./0 ./0/0 ./0/1 ./0/2 ./0/3 ./1 ./1/0 ./1/1 ./1/2 ./1/3 ./2 ./2/0 ./2/1 ./2/2 ./2/3 ./3 ./3/0 ./3/1 ./3/2 ./3/3