X display accessible to all local UNIX sockets

Mon Oct 30 12:12:42 PST 2006

Dean Loros wrote:

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[Posting HTML-only email doesn't help your chances of getting a reply. 
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> I'm running the "newest" version of X with Ubuntu Edgy Eft 6.10--My
> question is how to get the X display to show my Boinc Seti
> data--according to the Debian Boinc Wiki--<br>

>   <p>Graphics <strong>are</strong> supported, but they won't show up
> by
> default. The X display needs to be accessible to the BOINC graphics
> processes in order to see the interesting graphics for, e.g.,
> Einstein at Home, and it isn't by default. </p>
>   <p>Your X display can be made accessible to all local UNIX socket
> connections, including the ones from BOINC, by running </p>
>   <pre>xhost +local:
>   </pre>
>   <p>This is generally safe on single-user machines, though not ideal.
> It
> is a bad idea on multi-user machines, so don't do it there. </p>
>   <p>Then, the "Show graphics" button in boincmgr, or the <tt>--result ... graphics_window</tt>
> option to boinc_cmd, will actually work. Unfortunately, when it doesn't
> work because of failed X authorization, it does not report the error
> back to boinc_cmd or boinc_mgr, and the only trace of the error is in
> some log file in the result directory <tt>/var/lib/boinc-client/slots/<whatever></tt>.
>   </p>
> </blockquote>
> <p>However--this did work in the older version of X that I was running
> with Ubuntu Dapper 6.06---but not with the new 7.1.1 in Edgy 6.10.<br>
> </p>
> <p>Anyone have a idea what has changed to exclude the xhost -local:  or
> is the expression wrong?  Also--I would like the data to be available
> to Xscreensaver, are there any ideas to accommodate this?<br>

xhost doesn't have any effect if the X server is using authentication.

Historically, authentication would be used if you start the X server
using a display manager (xdm, gdm etc), but not if you use startx. 
Nowadays, it's not uncommon for the startx script to also enable
authentication.

When authentication is used, the startup sequence will create the file
~/.Xauthority in the home directory of the user who started X. X
clients need to be able to read the authentication data from this file
in order to connect to the X server.

Either copy the file to the home directory for the account under which
the Boinc process runs, or copy it to a location where that account
can read it (if your home directory isn't world-readable) and set the
XAUTHORITY environment variable for the Boinc process to the full path
to that file.

-- 
Glynn Clements <glynn at gclements.plus.com>