/dev/cdrom question

Jonathan Berry berryja at gmail.com
Sat Mar 19 04:56:25 UTC 2005


On Sat, 19 Mar 2005 03:43:53 +0000, C Toews <toewsc at hotmail.com> wrote:
> 
> I'm hoping this is a bonehead question with an easy answer:  I just
> installed Fedora Core 3 from a dvd.  The installation seemed to go fine, but
> I've noticed that /dev/cdrom doesn't exist, with the apparent consequence
> that I can't play CD's.  Except on a very cursory level, I don't really
> understand what the entries in the /dev directory represent, and in
> particular I don't understand when or how they are produced.  I do know that
> the cd drive works because I've checked it on the windows side (its a dual
> boot).  Any idea why the /dev/cdrom directory (directory?  file? I'm not
> sure what it is) wasn't created?  More relevantly, is there any way to
> create it, and associate with the relevant hardware?
> 
> Any ideas would be deeply appreciated.
> 
> Thanks,
> Carl

Hi Carl,
What exactly do you mean when you say you can't play CDs?  You mean
you cannot play audio CDs?  Or you stick a CD (data) in the drive and
cannot see it at all?
If you cannot play audio CDs, then I'd check several other things
first.  Check your volume levels.  For some reason, FC3 seems to
default (at least sometimes) to having sound disabled.  Check your
hardware.  Depending on how you are trying to play the CD, you may
need a cable that goes from the CD drive to your soundcard.  What
program are you trying to use to play the CD?  Further, this could be
a problem with sound in general.  Can you hear any sounds (play wav
files, etc)?
Linux is quite different in the way it handles hardware devices.  Each
device in your system (a device is something that you input from or
output to) is represented by a "file" in the /dev directory. 
Everything in the file system is a file or some kind.  There are
directory files, actual files, symbolic link files, and device files
(to name a few).  Now, if /dev/cdrom were to be created on your
system, it would be a symbolic link (or symlink for short) to /dev/hdX
where X is a, b, c, d, etc. depending on how your cdrom drive is
hooked up (or at least it is a symlink on my system).  It uses hdX
because it, like a hard drive, is connected through the IDE bus.  My
cd-rom is actually /dev/hdc (secondary master on the IDE bus).  I
suggest you look and see if you can find a similar file.  It also may
have multiple symlinks to it, like cdwriter or dvd depending on what
your system decided it liked (you obviously have a DVD drive, since
that is how you installed).
If your program you are trying to use is looking for /dev/cdrom, and
it cannot find it, then I suggest figuring out what hdX is the cdrom
and pointing it to that instead.
Yes, there is a way to manually create device files, it's called
MAKEDEV in the /dev directory.  But that is somewhere you don't really
want or need to go.  If your cdrom is really not having a device file
made for it, then I don't know what is going on.  If you need help
figuring out which /dev/hdX is you cdrom drive, the take a look at
fstab.  Run this command in a terminal:
cat /etc/fstab
Lines containing /media/<some_optical_drive_name> should give you some
clues.  If you are still stuck, then send us some more details about
what you want to do and what you have tried that has not worked.

Jonathan




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