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Re: group video?

>>>>> "Lee" == Lee Bradshaw <lee@sectionIV.com> writes:

    Lee> Your posting made me wonder about the proper setup for the
    Lee> scsi generic devices.

    Lee> I have /dev/scd0 as a read-only CDROM, and /dev/scd1 as a cd
    Lee> writer.

If I recall, cd writing applications use the generic scsi devcies too.

    Lee> To rip CD's, cdparanoia needs access to the scsi generic
    Lee> devices. I tried permissions of:


    Lee> If I change the permissions on all the sg devices to group
    Lee> rw, I can run cdparanoia as a normal user in group cdrom. But
    Lee> I don't want to have all the scsi generic devices writeable
    Lee> by everyone in group cdrom.  And setting just the correct
    Lee> scsi devices to be writeable is dangerous, because modifying
    Lee> the devices on the scsi bus may cause the generic devices to
    Lee> point to different physical devices. That is, if I make the
    Lee> scsi generic device for the cdrom writeable, it may be the
    Lee> scsi generic device for a hard drive after some hardware
    Lee> modifications.

Yes, I thought this too.  And yes, it does concern me, especially as I
plug in external SCSI devices from time to time.  The safest thing
would be to have a script run at system boot that sets the permissions
on the appropriate sg files depending on the contents of
/proc/scsi/blah-blah-blah.  In the meantime, I'll be trying to make
sure I have all my internal devices on low SCSI ids and leave the high
ones for external devices.

    Lee> Does anyone see a problem with my /dev setup? Does cdparanoia
    Lee> really need write permission to a cdrom drive in order to
    Lee> find it?

Yes, it seems it does.  Remember, the sg* devices allow the program to
send commands to particular devices on the SCSI bus, so therefore they
must be writable by whoever's running the application.


ADML Support, EUCS, The University of Edinburgh.

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