Sometimes you will try to unmount a disc and get a 'device is busy' error:
# umount /mnt/dvdrw
umount: /mnt/dvdrw: device is busy
I am using /mnt/dvdrw in this example, but the same goes for any disc, like /mnt/cdrom, /dev/hdc, etc.
fuser
You can see what users and processes are accessing disc with the fuser command:
# fuser -u /mnt/dvdrw
/mnt/dvdrw: 8159(bn) 8162(root)
The -k switch should kill the processes, allowing you to umount the disc.
# fuser -k /mnt/dvdrw
/mnt/dvdrw: 8159 8162
lsof
The lsof command can be used to do a similar thing:
# lsof -t /dev/dvdrw
8159
8162
Use of the kill command with this will attempt to kill the processes:
# kill -9 `lsof -t /dev/dvdrw`
umount
By now you should be able to unmount and eject the disc.
# umount /mnt/dvdrw # eject
Doesn't work?
If the processes have become zombies, then you may not be able to kill them and umount the disc. In this case you can use a lazy umount to detatch the filesystem and umount the disc.
# umount -l /mnt/dvdrw
