The chmod gotcha that I hit occasionally when I haven't used the chmod command for a while is the difference between "chmod -R <perm> <dir>" which recurses as w

The chmod gotcha that I hit occasionally when I haven't used the chmod command for a while is the difference between "chmod -R <perm> <dir>" which recurses as would be expected and "chmod -r <perm> <dir>" which interprets "-r" as the <perm> spec, complains that the file <perm> doesn't exist, then removes read permission from <dir>.