calculate disk usage first level dirs on a volume

gistfile1.txt

$ cd /
# ls -lrt | awk '/^d/ {print $9}'
for dir in `ls -d */`
do
# check those dir which are under /
CHECK_DIR=$(df $dir | awk '( $6 == "/" ) ')

# if dir under / then run du
[[ -z $CHECK_DIR ]] || du -sh $dir
done