Hi all:

Well, I'm a relative newbie to Linux, and apparently, I didn't learn the first time not to work on my box late at night.

When doing some work, I just erased the /dev/dvd file instead of erasing the symbolic link. Just to make matters worse, I also created a new, blank file, with the same name.

Is /dev/dvd a special file or is it generic? Can I recreate it somehow or am I screwed?

Oh, the machine is KnoppMyth (Debian Sarge 2.6.9 custom kernel).

I'm desperate for help

Thanks for any input.


newmoon

Well, it all depends. If you have udev, you could just remove the file and reboot. Otherwise, there's probably a "MAKEDEV" script in you /dev that you can use to recreate it.

Matir:

Thanks for your quick reply!
Well, I'm not using udev, AFAIK.

I looked around for a makedev file, but there were several files by that name. The one in /dev directory was tiny, and when I looked at it, barely contained any code.

Should the file you're talking about end in ".sh" ?

What repercussions would running that script have?


Thanks again.

newmoon

I think just running "/dev/MAKEDEV.sh dvd" should work... it's been a while since I've used raw dev nodes... you could try googling for relevant info.

Well, unfortunately:

What can I try next.

Thanks

newmoon

Which device is your dvd drive? hda, hdb, hdc, hdd? It should show up in 'dmesg' somewhere (dmesg | grep -i dvd). See if that exists. If so, just ln -s /dev/DRIVE_FROM_DMESG /dev/dvd

Thanks.

But I'm confused. Don't I need the actual dvd device file there, as opposed to just a blank file with a link? If so, is this file standard? Perhaps if it is, I could just get another copy from someone with the exact same distrib?



newmoon

Dev files don't actually do anything, per se. On my computer, /dev/dvd is a symbolic link to /dev/hdd, for example.

My setup is similar to Matir's. /dev/cdrom or /dev/dvd are just symbolic links to /dev/hde or whatever the physical drive is. My main system, for example, has 3 hard drives, 1 CD-RW, and 1 DVD-RW. Rather than trying to keep track of whether a drive is HDA, HDE, or whatever each drive is, I have sym links to keep them organized. This makes it easier to setup in Fstab or when mounting.

If /dev/dvd is symbolically linked to the correct device (/dev/hdc), then reconnecting the link should work.

That SHOULD work assuming /dev/hdc is your Optical drive (or the DVD one, if you have more than one Optical drive).
Someone correct me if I'm wrong, but if you create a symbolic link, doesn't it create the file that is linked? In my understanding, the above command should create a file called /dev/dvd and it would be linked to /dev/hdc.

Creating a symbolic link creates a special file of type link (on filesystems that support such operations). In effect, the only way to have a link is to have such a file, and the only way to have such a file is to have a link.

Creating a symlink does NOT create the destination of the symlink (/dev/hdc above).

It would not create /dev/hdc but you could use mknod /dev/hdc or makedev /dev/hdc to create the destination file correct? I'm still learning and thought it might help newmoon some as well.

Chromezero is right. If hdc and hdd already exist in /dev (or whatever device is your dvd-rom), then all you have to do is link to it. If you also deleted the actual device file, you can use mknod to restore it. Look in /proc under under ide to determine the major and minor numbers. It's a little tricky, you'll need to cat a lot of the files in /proc/ide and compare them with the output of ls -l /dev/hd*. Or someone might just come along after me and post the numbers for you.

Hope this helps

Thanks guys. I'm trying to understand something.

Let's say I were to use MAKEDEV (so I can learn how, and so I can say that I did). :-)

Would I use the device characteristics for hdc ? What repercussions would that have as opposed to using a symbolic link?


I checked this guide:
faqs.com: Linux Administrator guide

and according to that, I should consult my "devices.txt" file. I did that, and it specifies /dev/hdc as block device, major: 22 minor: 0 .

So would it work if I did:
What owner and group and perms are usually given for dvd-anyone know?


Thanks again.


newmoon

dvd is usually just a symbolic link to the hdx device - that *is* the norm. To have an actual dvd /dev entry, you'd have to change the way dev node names are assigned.