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Permissions lost on reboot for reading CD-ROM drive

Posted on 2007-04-08
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Last Modified: 2013-12-16
I am running Suse 10.2 on a HP500 laptop.  Recently I modified the kernel to enable touchpad functionality.  Now the CD-ROM permissions (/dev/hdb) are set for "root" and "disk" but not for me or the group I belong to ("users").  I can restore the correct group or user permissions using chown or chgrp, but the changes are lost when I reboot and permission is denied again.

How can I set the permission to be permanent?  Or do I have to run a script each time I boot to do it for me?
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Question by:Bloodrule
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Expert Comment

by:ygoutham
ID: 18874403
edit /etc/fstab and add the options there

/dev/cdrom              /mnt/cdrom              udf,iso9660 noauto,owner,kudzu,ro 0 0

the options can include the "users" option as well
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Author Comment

by:Bloodrule
ID: 18884727
I entered this line to /etc/fstab:

/dev/cdrom   /mnt/cdrom   udf,iso9660   noauto,owner,users,kudzu   0 0

(my default group is "users")

After rebooting /dev/hdb is still inaccessible, showing its permissions as ownership belonging to "root" and group "disk"

Have I omitted something?
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Expert Comment

by:infleadorix
ID: 18890220
Observe the output of the following commands:

# ls -l /dev/cdrom

Assuming that /dev/cdrom is a symlink to /dev/hda, create the /etc/udev/rules.d/99-my.rules file with the the following line in it:

KERNEL="hda", OWNER="username", GROUP="groupname", NAME="%k"

Replace username and groupname above with whatever you desire. Then either reboot the system or run the following commands:

# pkill udevd
# udevstart
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Author Comment

by:Bloodrule
ID: 18893508
Thanks but still no luck.  I wasn't sure if your suggestion needed to include the " " around the entries or not so I tried both ways.  This is what resulted:

ls -l /dev/cdrom produced:

lrwxrwxrwx 1 root root 3 2007-04-12 07:09 /dev/cdrom->hdb

So I created a new file 99-my.rules in /etc/udev/ with only one line as follows:

KERNEL=hdb, OWNER=peter, GROUP=users, NAME=%k

After rebooting, ls -l /dev/hdb produces:

brw-r----- 1 root disk 3, 64 2007-04-12 07:09 /dev/hdb

And the CDROM is stil inaccessible if I am logged in as "peter" but is available if I am logged in as root.

Can you see if I have made a mistake?
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Expert Comment

by:infleadorix
ID: 18893664
I'm not sure where the 99-my.rules file is supposed to be located in SUSE, but I know it should be in the same directory as the other *.rules file.

Use quotation marks as shown in my example.

I'm not sure what you meant exactly when you said the CD-ROM is inaccessible. Did you mean that you want to be able to mount the drive as regular users? If so, just edit your /etc/fstab file with the following mount options:

noauto,user,ro,exec
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Author Comment

by:Bloodrule
ID: 18893745
I found a number of .rules files in /etc/udev/rules.d/, though there was no file called 99-my.rules.  I assumed that was to be a new file that I was creating.

What I meant was that if I boot as an ordinary user, the CD-ROM device is visible but I get permission denied messages if I try to use it eg play an audio CD.  If I am logged in as root, it works normally.

I'll try again...and thanks!
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Author Comment

by:Bloodrule
ID: 18900887
Still no luck.  Despite making the edits you suggested and rebooting, /dev/hdb is still forbidden unless I am root so I cannot play an audio CD or read/write to/ from a data CD while logged in as an ordinary user.

Hope you have some further advice.
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Accepted Solution

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infleadorix earned 1500 total points
ID: 18902108
In that case, you might need to resort to the post initialization script, /etc/rc.d/rc.local. I don't have any SUSE machine here, so I'm not sure if the command I'll tell you (based on Red Hat) will work. Enter the following command:

# which start_udev

If the script exists, add it to the end of the /etc/rc.d/rc.local file, as follows:

/sbin/start_udev
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Author Comment

by:Bloodrule
ID: 18904102
Eventually I solved this as follows:

Yast/Security & Users/User Management/Users/Edit/Existing Local User/Details/Groups and checked the checbox against "Disks".  This gave the necessary permission after logging off and back on.

Thank you for your help.
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