Richard England wrote:
john bray wrote:
On Sun, 2006-01-15 at 17:05 +0100, Toralf Lund wrote:
Toralf Lund wrote:
How can I update permissions on a device file on an FC4 setup?
I mean, I know I can use chmod, of course, but the problem is
that for /dev special files, the changes are lost on reboot. [
... ]
grep -n "sg" /etc/udev/permissions.d/50-udev.permissions
The permissions are set there.
Right. I haven't quite got used to this new(ish) udev stuff...
Seems to me now it must be the place for the setting I want, but
the location you mention can't be correct for my system, as
/etc/udev has no permissions.d.
Look to /etc/udev/rules.d
HTH
I think I should be able to define an appropriate rule for my unit,
but I'm surprised to find that the udev doc does not mention a key
containing the device type or vendor/product id (as reported e.g.
in /proc/scsi/scsi.) Is there really now way to do direct match on
those?
Actually, it may look like SYSFS{type} will give me what I want (for
device type.) I now have added
KERNEL=="sg0", BUS=="scsi", SYSFS{type}=="6", SYMLINK="scanner",
MODE="0666"
which quite definitely has an effect, but not the one I want. In
fact after I did this, the device is still owned by root and
accessible by nobody else (i.e. has mode 0600.) Then if a user logs
in via a local GNOME session, owner is changed to that user, and the
mode stays the same. This is the same kind of behaviour as for
CD-ROM, but is not right in this case, as I want to share the
scanner across the net (via saned or just startup of the scanner
software via ssh.) In fact, I'm not happy with the general trend of
assuming the desktop user "owns" everything, as to me, flexibility
in sharing resources is a very large part of what Linux is or should
be about.
Anyhow, how do I get udev to actually use the mode I've told it to
use???
- Toralf
hey toralf -
i had that same frustration. i was sure that udev wasn't properly
setting the permissions. but...
i suspect that udev is doing the proper permissions. what you are
seeing is the result of the pam security stuff
in /etc/security/console.perms.d
when a user logs in, the devices controlled by that system, have their
owners and permissions changed as specified.
i just finished putting up a file in that directory called local.perms
because of scanner problems here. the scanner part is:
<scanner>=/dev/scanner* /dev/usb/scanner* /dev/sg*
# permission definitions
<console> 0666 <scanner> 0666 root
i'm not yet sure that the /dev/sg* part is necessary. note that 666 may
not be what you want. but, i sometimes su to other users for testing
and its more convenient for me.
you can use udevstart to rescan for devices and it appears to also force
the console/pam stuff to re-do things as well.
it appears that the perms files need to be named the reverse of the udev
rules files. as i currently understand it, with the perms files, the
last one read is the winner. but, with udev, it seems to be the case
that the first one found is the winner. so, my local udev rules are
named 10-local.rules but, my local console perms file is named
local.perms, so it gets parsed after the 50-* file does.
still in the process, so YMMV.
john
This may be ancient history but I don't believe I ever saw a follow-up
to this.
I followed your instructions, John, and after a logout/login the
permissions on my scanner were opened to all my users.
Thanks for sharing this information.
Arghh. Spoke too soon. I can, indeed, get xsane to come up as a user
or as root, but neither of them will scan. I get a "device busy"
warning box and no scanning. Back to google.
FYI, Canon LiDE 50 (USB scanner) on Fedora 5 full updates (at the moment).
--
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Registered Unix <http://counter.li.org> user #409453
