script to detect if beamer is on or off

currently logs to syslog
could make the screen go up/down automatically
e.g. down on beamer on, up on hackerspace closed

scripts/beamerdetect.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+prevstatus="unknown"
+while true
+do
+  projip=$(arp -an|awk -F'[()]' '/00:50:41:79:d1:34/{print $2}')
+  # from the acer webpage we read that bytes 30-31 contain 00 if poer off and 01 if power on
+  # we only test if 01, because if off, it can also give no response
+  # but seems to be bytes 32-33 more accurate
+  statusbyte="$(wget -qO - 'http://10.2.113.104/tgi/return.tgi?query=info'|awk -F'[<>]' '/<info>/{print substr($3,31,2)}')"  
+  if [ "$statusbyte" = "01" ]
+  then
+    if [ "$prevstatus" != "on" ]
+    then
+      logger -t $(basename $0) "$$ Projector is on"
+      prevstatus="on"
+    fi
+  else
+    if [ "$prevstatus" != "off" ]
+    then
+      logger -t $(basename $0) "$$ Projector is off"
+      prevstatus="off"
+    fi
+  fi
+  sleep 10
+done