Help: the problem to run GUI program with cron when logged out

[Xiaoshen Li]

Hi,

Many people say that it is a simple fix to let cron run a GUI program: just export DISPLAY=:0.0 -- telling where to display it. However, it is hard and even impossible for me.

(I am using "env -i script_name" to test) 
Suppose my script "run_gui.sh" can be run successfully:

env -i /path/run_gui.sh

Within run_gui.sh, there are:
export XAUTHORITY=xxx
export DISPLAY=:0.0
..
start the Java GUI program //this program is an automatic GUI program. It runs for about one minute or so, then shut down automatically. No human interaction is needed.

If I put run_gui.sh on cron and logged out(These linux machines are shared desktops, not my personal machines). Our IT support told me that my gui program have no place to put the display.(Since I have logged out, everything has closed). I told them that many people on newsgroup say that it is possible and they don't think so.

Another problem is that, since I was not logged in when the cron job("run_gui.sh") was running, so there is no XAUTHORITY value.

I am just confused: many people say it is possible to run a GUI program by cron. I assume that means they are not logged in when the cron job is run. How come it is impossible for me?

Thank you very much.