can't see non-root writes to /dev/console
Carlos A. M. dos Santos
unixmania at gmail.com
Thu Sep 11 01:54:28 UTC 2008
On Wed, Sep 10, 2008 at 5:34 PM, Jeff Blank <jb000002 at mr-happy.com> wrote:
> I just upgraded a RELENG_7 (amd64) box from 20080714 to "latest"
> (which seems to be from a few days ago--no changes from Monday
> morning's csup to today's) and can no longer see the effect of writing
> to /dev/console as non-root. When I log in using xdm, my user owns
> /dev/console, mode 0622 (-rw--w--w-), and I start an 'xterm -C'. But
> when I, for example,
> echo foo > /dev/console
> I see nothing in the console xterm. No error messages, and echo exits
> 0. If I su to root and do the same, I get 'foo' in the same console
> xterm. Syslog messages to /dev/console also appear, of course. All
> the above applies to xconsole as well, not just xterm. I did
> recompile xterm from 20080616 ports, but it didn't fix the issue
> (didn't expect it to, as xterm clearly has no trouble attaching and
> reading). So my echo is getting lost in the kernel, I guess.
> Known problem? Intentional change? Something else?
I have seen this problem since 6.x times and still on 7.x. I also
noticed that if I send something to the console after xconsole starts
then I can sned messages as an ordinary user. My workaround was
modifying the Xsetup_0 script (I used xdm for login), adding a line
(sleep 3; date >> "$dev_console") &
just after starting xconsole.
I didn't have time to set up a machine with 8-CURRENT yet, so I could
not check if the new mp-safe tty implementation fixes this, either
intentionally or by a fortunate side effect.
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