How to unmount a device?

view story

http://www.linuxquestions.org – I'm trying to unmount a device as a whole! Take note that a device such as a HDD can have multiple partitions and some of them can be mounted while others are not. Is there an easy way to unmount an entire device i.e. all mounted partitions on a given device like /dev/sdb? Is there a single shell command (one-liner) for this? Or do I have to write a script that iterates through /dev/sdb*? Best regards! ~dis (HowTos)