Mounting and unmounting drives in Raspbian

Mount drive for the pi user

• sudo mount -t vfat /dev/sdb1 /mnt/usb32 -o uid=pi,gid=pi

Force unmount

• sudo umount -l /mnt/usb32

Also, make sure that /mnt/usb32 is owned by the user you want be able to make modifications in it.

Source:

• http://www.raspberrypi-spy.co.uk/2014/05/how-to-mount-a-usb-flash-disk-on-the-raspberry-pi/
• http://stackoverflow.com/questions/7878707/umount-a-busy-device