This is a simple bash script to mount ntfs external drives on Mac Os.
Once mounted, both R & W are allowed.
Device will be mounted under /Volumes/[volume_name]
volume_name is referred to the name Mac Os assigns to the external drive when it's automatically mounted.
sudo mnt_ntfs [volume_name]
You can just use the umount tool.
sudo umount /Volumes/[volume_name]