Add a timeframe under that that the SSID will not change

This adds a configuration MINUTES, so it cannot happen more often than those minutes that the SSID is changed to offline

files/lib/gluon/ssid-changer/ssid-changer.sh

 #!/bin/sh
 
 # at first some Definitions:
+MINUTES=1440 # only once every this timeframe the SSID will change to OFFLINE
+OFFLINE_PREFIX='FF_OFFLINE_' # use something short to leave space for the nodename (no '~' allowed!)
+
 ONLINE_SSID=$(uci get wireless.client_radio0.ssid -q)
 : ${ONLINE_SSID:="FREIFUNK"} # if for whatever reason ONLINE_SSID is NULL
-OFFLINE_PREFIX='FF_OFFLINE_' # use something short to leave space for the nodename (no '~' allowed!)
 
 # Generate an Offline SSID with the first and last part of the nodename to allow owner to recognise wich node is down
 NODENAME=`uname -n`
@@ -18,14 +20,22 @@ fi
 CHECK=$(batctl gwl -H|grep -v "gateways in range"|wc -l)
 
 if [ $CHECK -eq 0 ] ; then
-  if [ "$(uci get wireless.client_radio0.ssid)" == "$OFFLINE_SSID" ] ; then echo "$0 - still on $OFFLINE_SSID" ; exit 0 ; fi
-  echo "$0 change ssid to $OFFLINE_SSID" | logger
-  uci set wireless.client_radio0.ssid="$OFFLINE_SSID"
-  sed -i s~^ssid=$ONLINE_SSID~ssid=$OFFLINE_SSID~ /var/run/hostapd-phy0.conf
-  killall -HUP hostapd
+  if [ $(expr $(date "+%s") / 60 % $MINUTES) -eq 0 ]; then
+    if [ "$(uci get wireless.client_radio0.ssid)" == "$OFFLINE_SSID" ]; then
+      echo "$0 - still on $OFFLINE_SSID"
+      exit 0
+    fi
+    echo "$0 change ssid to $OFFLINE_SSID" | logger
+    uci set wireless.client_radio0.ssid="$OFFLINE_SSID"
+    sed -i s~^ssid=$ONLINE_SSID~ssid=$OFFLINE_SSID~ /var/run/hostapd-phy0.conf
+    killall -HUP hostapd
+  fi
 fi
 if [ $CHECK -gt 0 ] ; then
-  if [ "$(uci get wireless.client_radio0.ssid)" == "$ONLINE_SSID" ] ; then echo "$0 - still on $ONLINE_SSID" ; exit 0 ; fi
+  if [ "$(uci get wireless.client_radio0.ssid)" == "$ONLINE_SSID" ]; then
+    echo "$0 - still on $ONLINE_SSID"
+    exit 0
+  fi
   echo "$0 change ssid to $ONLINE_SSID"| logger
   uci set wireless.client_radio0.ssid="$ONLINE_SSID"
   sed -i s~^ssid=$OFFLINE_SSID~ssid=$ONLINE_SSID~ /var/run/hostapd-phy0.conf