Hello ,everybody .
My problem is that I'm able to mount the DVD-ROM as a normal user , but when it comes to DVD play-back , root privilege is required . I've already edit /etc/fstab , so is there any other file that I need to edit to have the permission to play DVD as a normal user ?
Thank you for your time !

To play dvds, you'd need read access to your dvd drive. Please do 'ls -l /dev/DVD_DRIVE' where DVD_DRIVE is your drive, obviously.

What groups is your user a member of? Need to have "cdrom" in there for it to work properly.

Hi !
Thanks for the advise! I did ' ls -l /dev/cdrom ' which showed that I have all the permission and there is already a group called " cdrom" , should I add the normal user to this group or make another group called " dvdrom" ? And if the latter is the case , will the following commands do the trick :
#groupadd dvdrom
#chgrp dvdrom /dev/hdc
#chmod g+r /dev/hdc
#usermod -G dvdrom 'username'
You might ask why I don't just type them in and see what happens , well the truth is I did and it didn't work . So , any suggestions ?
Thank you for your time .

First, you have to relogin to apply changes in user groups.
Second, if you are running Slackware 10.1 I expect udev is used for dynamic handling of device files in /dev subtree so manual changing of ownership and permissions has no sense.
You'll either follow recommendations and join user to cdrom group or if you *need* to be handled by another group, you have to edit /etc/udev/rules.d/udev.rules to change entry(ies) for cdrom devices. Then udevd daemon has to be restarted to apply changes.

What permisions did ls -l /dev/cdrom show? I put

in rc.local to allow users to watch dvds.

priller, the /dev/cdrom permission do not matter
as it is a symlink, only the permissions of the file
it points to are important (you surelly know that
as you chmod /dev/hdc not /dev/cdrom)

The proper way is not chmod the /dev files but
instead add your user to the group the files
belong to (as it was posted above)

It is your personal choice though, but be warned
that with a 2.6 kernel running udev, you will have
to create your own rule to accomplish the chmod
solution

Just realised what I typed, it is /dev/hdc. I am running 2.6.11.12 kernel and I can change the permisions using chmod. I've used it since 9.0, I know the proper way is to use groups but I've done it this way since I started using linux and its stuck. But having the chmod in rc.local does work for me.

Yeah, but it's a hack - not a solution.

Sure, as the rc.local is executed after udev rules, your
rc.local solution works I just wanted to point out some
other way to make a device file usable by simple users

I know.