I want to have the following line in root's crontab so that the message appears on any users desktop ..... but it doesn't work ie nothing is displayed. Other cronjobs are working.

20 11 * * * xmessage -center -timeout 3 This computer will disconnect from the Internet in FIVE minutes

I have tried all sorts of variations (found on LQ) but the message never displays. I have tried the message in both single and double quotes. I have tried /usr/X11R6/bin/xmessage. I have tried -display:0 and -display :0.0 ..... <<< what am I doing wrong?

Thanks

So. To start a piece of software in an xterm I type "name of prog"...xmessage is no different except in that instructions have to be given to it ie xmessage <my message here> ... does this make a difference to the syntax of a cronjob?

right.
Can anybody test this in a crontab for me?

<you specify when> * * * xmessage test

Thanks

Strange --- the xmessage will not work from root's crontab to user's desktop but it works from user's crontab :
20 10 * * * /usr/X11R6/bin/xmessage -display :0.0 hello
so I will have one crontab for xmessages and a root one for network shutdown etc. It seems strange to me that I can't get xmessage to run from root's crontab >>> user but I haven't got the time t "play" any longer. If anyone can guide me I would be grateful.
Cheers
PS kdialog also refuses to work from root's crontab but works from user.