mkdir -p source/dir1/dir2
mkdir -p source/dir1/dir21/dir21-deep
mkdir -p source/dir3
mkdir -p source/dir40
mkdir -p source/dir41
touch source/file1.txt
touch source/file2.txt
touch source/dir1/dir2/file3.txt
touch source/dir3/file4.txt
touch source/dir1/dir21/file-21
touch source/dir1/dir21/dir21-deep/file21-deep1
touch source/dir1/dir21/dir21-deep/file21-deep2