joffrey@joffrey-desktop:~$ sudo mount -t ntfs-3g /dev/sda1  /media/ddexterne  -o force
Error opening partition device: Périphérique ou ressource occupé
Failed to startup volume: Périphérique ou ressource occupé
Failed to mount '/dev/sda1': Périphérique ou ressource occupé
Mount is denied because the NTFS volume is already exclusively opened.
The volume may be already mounted, or another software may use it which
could be identified for example by the help of the 'fuser' command.