new Ubuntu user w/ questions

[Rashkae]

Bob Holtzman wrote:
> I recently decided to try out Ubuntu and have a couple of questions. I have RT'd a couple of FMs
> and tried to wade thru this list's archives with no luck. I'm running Ubuntu 7.10.
> 
> 1. What is the purpose of having both /media/cdrom and /media/cdrom0? I realize one is a link 
>    to the other but I'm wondering why both exist. The same applies to /media/floppy and 
>    /media/floppy0.

Backwards compatability and improvements.  /media/cdrom(n) can exist for 
as many cd-rom devices as you care to cram on a single system, but 
/media/cdrom (which lots of people/programs expect as the default) can 
only point to one.

>    
> 2. When trying to add content to a rewritable DVD that has previously been written to I get the 
>    warning that I don't have permission to write to that directory. When I try to chmod 777(as
>    root)/media/cdrom0 I'm told it is a read only directory even tho /etc/mtab shows it mounted as rw. 
>    What am I missing?
> 

RW CD's and DVD's aren't really RW (huh, please, bear with me).  The 
ISO9660 file system used by default only works as a complete image, and 
does not allow for random write access (data is recorded in a continuous 
spiral track, not divided into sectors / blocks like a traditional hard 
drive.  There is a standard that exists to mount a RW optical device 
with random read write access, (if your drive supports it properly. Last 
I investigated this, most did not) but it's very rarely used.  I'm not 
sure what the status of this is in Linux or what packages you would need 
to get it working.  In general, think of RW Optical media as something 
you can erase and and start over.  (You can, of course, append a write 
session to add files.  Use your favorite DVD burning software.  You 
can't write directly to the mounted file system, however)