Linux du command without traversing mounted file systems

du -x will not traverse any mount points it encounters. But if it is told to start at a mount point then it will do as requested.

This is hacky, but it seems to do what you want, from the shell,

for d in /*; do egrep " ${d} " /proc/mounts > /dev/null || du -sh ${d}; done

Add a sudo in front of the du if needed.