How to spin down USB hard drive for safe removal

Let's assume you are running a Debian-based system and have a hard drive at /dev/sdc with a partition /dev/sdc1 mounted. To safely remove the hard drive, first you need to unmount all its partitions. In this case you may do:

udisks --umount /dev/sdc1

and then spin the disk down with:

udisks --detach /dev/sdc

You should the notice (usually, hear) the disk spin down.

Please note, that we are referring here to the device sdc not its partition sdc1.

Thanks, user76204.