Unmount and spin-down a drive.

unmount.sh

#!/bin/bash

DRIVE_NAME=${1:-Backup}

if [ -z "${DRIVE_NAME}" ]; then
    echo 'No drive found.' 1>&2
    exit 1
fi

drive_dir="$(mount -l | grep "\[${DRIVE_NAME}\]" | awk '{print $1}')"
drive_dir_no_num=$(echo ${drive_dir} | sed -E 's,/dev/([a-z]*).*,/dev/\1,g')

# Unmounts and spins down an external drive.
udisks --unmount ${drive_dir}
udisks --detach ${drive_dir_no_num}