eject -- Eject the removable media

Eject allows removable media (like CD-ROM, Floppy, Tape, JAZ, ZIP) to
be ejected under software control. The command can also control some
multi-disc CD-ROM changers, the auto-eject feature supported by some
devices, and close the disc tray of some CD-ROM drives.

Examples:

$ eject -- Eject the default device, mostly CD.

$ eject -v -- Same as above and show more info.

$ eject /dev/cdrom -- Eject CD using device file name.

$ eject -t -- Close the drive tray.

$ eject -vt -- Same as above and show more info.

Read: man eject

Umounting a bad CD

To unmount a CD which is not unmounting with the normal procedure

try this
1.)fuser -k
or
fuser -k /dev/cdrom

whatever ur device name is
or
2.) umount -lf /dev/cdrom
eject /dev/cdrom Last Updated ( Tuesday, 05 July 2005 )

Allowing users to run root programs

When a user starts a command, it runs with the permissions of that user. What if you want to allow them to run some commands with root permissions? You can, and that's called suid.You can set a command to be suid root with the chmod command. This will make it run as root even if a user starts it. Here is how to set mybin suid root:

chmod +s mybin

Note that you must be very careful with this option. If the command has any security hole, or allows the user
to access other files or programs, the user could take over the root account and the whole system.

To set suid bit is also dangerous.....be careful before setting a suid bit
Must Read this...

mtools : Accessing dos Disks

mtools - utilities to access DOS disks
Mtools is a public domain collection of tools to allow systems to manipulate MS-DOS files: read, write, and move around files on an MS-DOS filesystem (typically a floppy disk).
for more info look

man mtools

If they are not installed ,they can be found at
http://mtools.linux.lu/mtools-3.9.8.tar.gz
ftp://www.tux.org/pub/knaff/mtools/mtools-3.9.8.tar.gz
ftp://metalab.unc.edu/pub/Linux/utils/disk-management/mtools-3.9.8.tar.gz