while true; do
  xev -root -event property | grep DESKTOP 1&>/dev/null
  DESKTOP=$(xprop -root | grep CURRENT | head -1 | sed -e 's/.*= //')
  echo -e "desktop\t$DESKTOP" >> /tmp/dzen2_events
done &
PID_XEV=$!

while true; do
  ip monitor link | grep 'status' 1&>/dev/null
  echo -e "network" >> /tmp/dzen2_events
done &
PID_IP=$!


[ ... ]

kill -TERM -- -$PID_TAIL
kill -TERM -- -$PID_XEV
kill -TERM -- -$PID_IP
kill -TERM -- -$$

exit 0