Forcefully Unmounting: Mount point is busy

Trying to forcefully unmount any device like NFS or CD-ROM and getting an error or 'mount point is busy' ?


Mount point is busy
Text file is busy
This is the case most of the time where most beginners restart the machine to kill those processes which are accessing the device due to which they are unable to unmount.
The only thing you need to do is find those processes which are trying to access that device and kill them.
There are various ways to do so among which I will show you some which I know and use to do the same.
NOTE: If the mount point is for NFS, clear the NFS entry from mtab
# vi /etc/mtab
# lsof | grep (mount point)

this will show you the process IDs which are accessing the mount point. Once you get the process IDs you can kill them manually.

# kill -9 (process ID)

This command is useful if a particular file is shown as busy rather than a directory.

# fuser -km (filename)

-k kill the process accessing the mentioned file
-m specifies the file on a mounted file system or a block device i.e. mounted
Once done you can unmount the device

# umount (mount point)