[K12OSN] More on terminal screen locking.... need help w/ xauth (what's up with /tmp/.gdm*)

[Henry Burroughs]

I'm close.  I've  figured out how to control the screens via root and
doing a:

su - $USER -c "DISPLAY=<their display> xscreensaver-command -lock"

However, it depends on the user having a CURRENT .Xauthority file in
their home directory.   However, the authority information is being
stored and used in a file in /tmp (/tmp/.gdm* files) according to "xauth
info".  Does anyone know why it is being created there? I  can copy the
/tmp/.gdm?????? file corresponding to that user's authority file, and
can achieve a screensaver lock (or start any other program on their
display) via above, however logging the user out and back in does not
make it use the new .Xauthority file (so it wouldnt' work on a different
workstation).

I think I'm  pretty close to getting a partial solution.  I'm trying to
figure out xauth to some extent so I can avoid "xhost" at all costs. 
I'll be sure to post to the wiki my solution.

Henry Burroughs
Technology Director
Hilton Head Preparatory School
www.hhprep.org