It sometimes happens that a device can not be unmounted.
When mounting from nautilus, "Volume is busy" titled dialog appears with following content: "One or more applications are keeping the volume busy".
If trying with the
umount command, the command exits with error: "umount: /media/transang/SangWDPP: target is busy.".
How to figure out reason and fix?
Assume that the path of the directory being mounted is
lsof can be used to find out which process is keeping the device busy
# sudo lsof | grep /media/transang/SangWDPP zsh 48966 transang cwd DIR 8,49 131072 1 /media/transang/SangWDPP
Now, we know that there is a zsh terminal which may
cding at the being mounted directory. After the terminal is closed, the device is now able to be unmounted via either the
umount command or nautilus icon.