On Tuesday, January 18, 2011 09:00:22 am Robert Nichols wrote: > On 01/18/2011 01:34 AM, Rick Sewill wrote: > > On Monday, January 17, 2011 10:57:00 pm Robert Nichols wrote: > >> On 01/17/2011 09:57 PM, Rick Sewill wrote: > >>> Question please: > >>> > >>> Can you use > >>> gnome-screensaver-command -q > >>> > >>> man gnome-screensaver-command > >>> > >>> I'm currently trying out KDE so I don't know > >>> what is returned by the above command for the > >>> various gnome-screensaver states. > >> > >> As I said in my original message, when run from a cron job that fails: > >> ** Message: Failed to connect to the D-BUS daemon: > >> /bin/dbus-launch terminated abnormally with the following error: > >> Autolaunch error: X11 initialization failed. > >> > >> And yes, I did try it with "DISPLAY=:0.0" in the environment. > > > > You have a good puzzle! > > > > I read all the responses for the problem, > > http://www.mail-archive.com/debian-kde@xxxxxxxxxxxxxxxx/msg30421.html > > > > I tried to condense their answer to the following...please give it a try: > > > > I created a file, ${HOME}/bin/testscreensaver > > ===== Please begin contents of file testscreensaver with following line > > #!/bin/bash > > > > # We must set the DISPLAY variable so dbus is happy. > > > > export DISPLAY=:0.0 > > > > # We must find the DBUS_SESSION_BUS_ADDRESS so dbus is happy. > > > > for pid in $(pgrep -u $USER) > > do > > > > declare DBUS_SESSION_BUS_ADDRESS=$(cat /proc/${pid}/environ | \ > > > > tr '\0' '\n' | grep "DBUS_SESSION_BUS_ADDRESS=") > > > > # I looked for the first DBUS_SESSION_BUS_ADDRESS found. > > > > [ -z "${DBUS_SESSION_BUS_ADDRESS}" ] || break > > > > done > > > > > > # Strip off the DBUS_SESSION_BUS_ADDRESS= string at the beginning. > > DBUS_SESSION_BUS_ADDRESS="${DBUS_SESSION_BUS_ADDRESS:25}" > > > > # I echo it for debugging purposes...you probably don't want to echo it. > > echo "Set bus address to<${DBUS_SESSION_BUS_ADDRESS}>" > > > > # If I have a string, I call the gnome-screensaver-command > > [ -z "${DBUS_SESSION_BUS_ADDRESS}" ] || gnome-screensaver-command -q > > > > ===== Please end file testscreensaver with previous line > > Hmmm, in that script you're not doing anything with > DBUS_SESSION_BUS_ADDRESS beyond testing for non-null (it's not exported), > so "Set bus address to" is a misnomer. "Found bus address" might be more > to the point. It does test whether this user currently has a session, > which is useful. > Please see "man dbus-daemon". I believe the variable, DBUS_SESSION_BUS_ADDRESS, must be set for desktop applications to find the per-session daemon to have interprocess communication amongst themselves. From "man dbus-daemon", I am referring to the per-session daemon, not the systemwide daemon. I believe gnome-screensaver-command attempts to use the per-session daemon to talk to gnome-screensaver. I made the assumption all $USER processes, where DBUS_SESSION_BUS_ADDRESS was defined, would be the same, and associated with the current, user session. This is remiss of me. To be pedantic, one may need to check the /proc/${PID}/environ special file for the value of the DISPLAY variable, to insure the session isn't a remote ssh or other remote session. I didn't insure /proc/${PID}/environ was readable. Perhaps others can suggest other and better checks. There are other interesting things mentioned in "man dbus-daemon". Please see the DEBUGGING section. It speaks of running dbus-monitor. It speaks of running a test copy of dbus-daemon, and how to communicate with the test copy by setting the DBUS_SESSION_BUS_ADDRESS for the applications you want to test with the test copy of the dbus-daemon. > OK, now it looks like I might just have been hit by a glitch. On another > machine, I found that > > DISPLAY=:0.0 gnome-screensaver-command -q > > works just fine in a cron job. After rebooting the desktop system where > I'd been having the problem (system had been up 22 days with me poking > around trying things), it works fine there, too. > I am surprised, given what I read about DBUS_SESSION_BUS_ADDRESS, this would work without DBUS_SESSION_BUS_ADDRESS being set. What version of software are these other machines using? > So, all I can say is, "Sorry for contributing to the noise here." At least > I've learned a few things from some of the responses. Thanks, all. It is not noise. Your question is a good one. I enjoyed looking up things. If my answer is wrong, I hope others gently correct me.
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