Hello everybody,

my scenario: in my company 6 colleagues are working in the same office building as I am and 2 are only working from their home office. We are all using the same server placed "out of sight" in an other building and are connected via x2go (TCE in the office) to the server.

The server (running UBUNTU 14.04) is protected against power loss by an ups that is monitored via usb and NUT on the server. The problem is to send messages regarding critical conditions (e.g. power loss) to all - via x2go - connected users. This is necessary because the NUT NOTIFYCMD script starts a controlled shutdown sequence (putting several running virtual machines to safestate a.s.o. and finally shutting down the server) after 3 minutes running on battery.

These messages are send by nut via wall automatically but this is not the way as none of the users has open a terminal - all are working under their LXDE/OpenBox GUI.

I asked the internet but only found one hint - and I have to say thanks to Timotheus Pokorra who gave me the direction with his post: http://tpokorra.blogspot.de/2013/07/notify-all-users-logged-in-over-x2go-on.html

I tested this and it did not work - so I designed the following solution:

(this will be a /THE part of the notifycmd script from nut)

#!/bin/bash
#
# NUT NOTIFYCMD script

PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/sbin:/usr/local/bin

# ...
#if [ "$NOTIFYTYPE" = "ONBATT" ]
#then

   # compose message for wall
    message="$(date "+%d.%m.%Y - %H:%M:%S ")$(cat /usr/local/bin/eam01.txt)"
    echo $message | wall

   # send message to admin by e-mail
   echo 'EAM - '$HOSTNAME' - '$(date)' Benutzer: '$USER 'USV meldet STROMAUSFALL / ONBATT !' | mail -s 'EAM from'$HOSTNAME admin@xxxxx.xx

   # get infos for x2go-user-information
      benutzer=`ps xaf | grep x2goagent | grep -v grep | awk ' { print ( $(NF-2) ) }' FS='-'`     # get the user names
      screens=`ps xaf | grep x2goagent | grep -v grep | awk ' { print ( $(NF-1) ) }' FS='-'`       # get the user displays
      USERCOUNT="$(echo $benutzer | wc -w)"                                                                         # number of users / loops

   # start loop / action for every logged in x2go-user
    START=1
    i=$START
    while [[ $i -le $USERCOUNT ]]
    do
      user=`echo  $benutzer | awk -v a=$i '{print $a}'`                    # transfer contents (word 1,2,3...) of $benutzer to $user
      display=":"`echo  $screens | awk -v a=$i '{print $a}'`".0"        # compose $display (word 1,2,3... from $screens)) ":" & number from $screens & ".0"

   # send message to each x2go-user
      sudo -u $user -S -H sh -c "zenity --text-info --html --display=$display --filename=/usr/local/bin/eam01.txt" </usr/local/bin/pw.txt &

          ((i = i + 1))
    done

## Loop with one second interval to allow SIGTERM reception.
#let "n = 180"
#while [ $n -ne 0 ]
#do
#         sleep 1
#         let "n--"
#done
#echo $0: commencing shutdown | wall
#        upsmon -c fsd
#fi