diff --git a/ffac-ssid-changer/gluonShellDiet.sh b/ffac-ssid-changer/gluonShellDiet.sh
index 1cb74ad6..eef7c439 100755
--- a/ffac-ssid-changer/gluonShellDiet.sh
+++ b/ffac-ssid-changer/gluonShellDiet.sh
@@ -2,4 +2,4 @@
 
 # This script requires a file as argument in which it will remove all comment lines that start with a hash '#'
 
-sed '/^\s*\#[^!].*/d; /^\s*\#$/d' $1
+sed '/^\s*\#[^!].*/d; /^\s*\#$/d' "$1"
diff --git a/ffac-ssid-changer/shsrc/ssid-changer.sh b/ffac-ssid-changer/shsrc/ssid-changer.sh
index 430b81cc..a08d0fba 100755
--- a/ffac-ssid-changer/shsrc/ssid-changer.sh
+++ b/ffac-ssid-changer/shsrc/ssid-changer.sh
@@ -18,26 +18,27 @@ SETTINGS_DEBUG_LOGGING="$(uci -q get ssid-changer.settings.debug_log_enabled)"
 
 pgrep -f autoupdater >/dev/null && safety_exit 'autoupdater running'
 UT=$(sed 's/\..*//g' /proc/uptime)
-[ $UT -gt 60 ] || safety_exit 'less than one minute'
+[ "$UT" -gt 60 ] || safety_exit 'less than one minute'
 [ "$(find /var/run -name "hostapd-phy*" | wc -l)" -gt 0 ] || safety_exit 'no hostapd-phy*'
 
 # only once every timeframe minutes the SSID will change to the Offline-SSID
 # (set to 1 minute to change immediately every time the router gets offline)
 MINUTES="$(uci -q get ssid-changer.settings.switch_timeframe)"
-: ${MINUTES:=30}
+: "${MINUTES:=30}"
 
 # the first few minutes directly after reboot within which an Offline-SSID always may be activated
 # (must be <= switch_timeframe)
 FIRST="$(uci -q get ssid-changer.settings.first)"
-: ${FIRST:=5}
+: "${FIRST:=5}"
 
 # the Offline-SSID will start with this prefix use something short to leave space for the nodename
 # (no '~' allowed!)
+
 PREFIX="$(uci -q get ssid-changer.settings.prefix)"
-: ${PREFIX:='FF_Offline_'}
+: "${PREFIX:=FF_Offline_}"
 
 PREFIX_OWE="$(uci -q get ssid-changer.settings.prefix_owe)"
-: ${PREFIX_OWE:='FF_Off_OWE'}
+: "${PREFIX_OWE:=FF_Off_OWE}"
 
 if [ "$(uci -q get ssid-changer.settings.enabled)" = '0' ]; then
 	DISABLED='1'
@@ -47,20 +48,20 @@ fi
 
 # generate the ssid with either 'nodename', 'mac' or to use only the prefix set to 'none'
 SETTINGS_SUFFIX="$(uci -q get ssid-changer.settings.suffix)"
-: ${SETTINGS_SUFFIX:='nodename'}
+: "${SETTINGS_SUFFIX:=nodename}"
 
-if [ $SETTINGS_SUFFIX = 'nodename' ]; then
+if [ "$SETTINGS_SUFFIX" = 'nodename' ]; then
 	SUFFIX="$(uname -n)"
 	# 32 would be possible as well
 	if [ ${#SUFFIX} -gt $((30 - ${#PREFIX})) ]; then
 		# calculate the length of the first part of the node identifier in the offline-ssid
 		HALF=$(( (28 - ${#PREFIX} ) / 2 ))
 		# jump to this charakter for the last part of the name
-		SKIP=$(( ${#SUFFIX} - $HALF ))
+		SKIP=$(( ${#SUFFIX} - HALF ))
 		# use the first and last part of the nodename for nodes with long name
 		SUFFIX=${SUFFIX:0:$HALF}...${SUFFIX:$SKIP:${#SUFFIX}}
 	fi
-elif [ $SETTINGS_SUFFIX = 'mac' ]; then
+elif [ "$SETTINGS_SUFFIX" = 'mac' ]; then
 	SUFFIX="$(uci -q get network.bat0.macaddr | /bin/sed 's/://g')"
 else
 	# 'none'
@@ -76,7 +77,7 @@ ONLINE_SSID_OWE="$(uci -q get wireless.owe_radio0.ssid)"
 # get all SSIDs (replace \' with TICX and back to keep a possible tic in an SSID)
 ONLINE_SSIDs="$(uci show | grep "wireless.client_radio[0-9]\." | grep ssid  | awk -F '='  '{print $2}' | sed "s/\\\'/TICX/g" | tr \' \~ | sed "s/TICX/\\\'/g" ) "
 # if for whatever reason ONLINE_SSIDs is NULL:
-: ${ONLINE_SSIDs:="~FREIFUNK~"}
+: "${ONLINE_SSIDs:=~FREIFUNK~}"
 
 # temp file to count the offline incidents during switch_timeframe
 TMP=/tmp/ssid-changer-count
@@ -87,15 +88,15 @@ TQ_LIMIT_ENABLED="$(uci -q get ssid-changer.settings.tq_limit_enabled)"
 # if true, the offline ssid will only be set if there is no gateway reacheable
 # upper and lower limit to turn the offline_ssid on and off
 # in-between these two values the SSID will never be changed to preven it from toggeling every Minute.
-: ${TQ_LIMIT_ENABLED:='0'}
+: "${TQ_LIMIT_ENABLED:=0}"
 
-if [ $TQ_LIMIT_ENABLED = 1 ]; then
+if [ "$TQ_LIMIT_ENABLED" = 1 ]; then
 	TQ_LIMIT_MAX="$(uci -q get ssid-changer.settings.tq_limit_max)"
 	#  upper limit, above that the online SSID will be used
-	: ${TQ_LIMIT_MAX:='45'}
+	: "${TQ_LIMIT_MAX:=45}"
 	TQ_LIMIT_MIN="$(uci -q get ssid-changer.settings.tq_limit_min)"
 	#  lower limit, below that the offline SSID will be used
-	: ${TQ_LIMIT_MIN:='35'}
+	: "${TQ_LIMIT_MIN:=35}"
 	# grep the connection quality of the currently used gateway
 	GATEWAY_TQ=0
 	if [ -f /var/gluon/state/has_default_gw4 ]; then
@@ -104,9 +105,9 @@ if [ $TQ_LIMIT_ENABLED = 1 ]; then
 
 	MSG="TQ is $GATEWAY_TQ, "
 
-	if [ $GATEWAY_TQ -ge $TQ_LIMIT_MAX ]; then
+	if [ "$GATEWAY_TQ" -ge "$TQ_LIMIT_MAX" ]; then
 		CHECK=1
-	elif [ $GATEWAY_TQ -lt $TQ_LIMIT_MIN ]; then
+	elif [ "$GATEWAY_TQ" -lt "$TQ_LIMIT_MIN" ]; then
 		CHECK=0
 	else
 		# this is just get a clean run if we are in-between the grace periode
@@ -122,8 +123,8 @@ else
 	fi
 fi
 
-UP=$(($UT / 60))
-M=$(($UP % $MINUTES))
+UP=$((UT / 60))
+M=$((UP % MINUTES))
 
 HUP_NEEDED=0
 if [ "$CHECK" -gt 0 ] || [ "$DISABLED" = '1' ]; then
@@ -132,29 +133,29 @@ if [ "$CHECK" -gt 0 ] || [ "$DISABLED" = '1' ]; then
 	# check status for all physical devices
 	for HOSTAPD in /var/run/hostapd-phy*; do
 		[ -e "$HOSTAPD" ] || break  # handle the case of no hostapd-phy* files
-		ONLINE_SSID="$(echo $ONLINE_SSIDs | awk -F '~' -v l=$((LOOP*2)) '{print $l}')"
+		ONLINE_SSID="$(echo "$ONLINE_SSIDs" | awk -F '~' -v l=$((LOOP*2)) '{print $l}')"
 		LOOP=$((LOOP+1))
-		CURRENT_SSID="$(grep "^ssid=$ONLINE_SSID" $HOSTAPD | cut -d"=" -f2)"
+		CURRENT_SSID="$(grep "^ssid=$ONLINE_SSID" "$HOSTAPD" | cut -d"=" -f2)"
 		if [ "$CURRENT_SSID" = "$ONLINE_SSID" ]; then
 			log_debug "SSID $CURRENT_SSID is correct, nothing to do"
 			break
 		fi
-		CURRENT_SSID="$(grep "^ssid=$OFFLINE_SSID" $HOSTAPD | cut -d"=" -f2)"
+		CURRENT_SSID="$(grep "^ssid=$OFFLINE_SSID" "$HOSTAPD" | cut -d"=" -f2)"
 		if [ "$CURRENT_SSID" = "$OFFLINE_SSID" ]; then
 			# set online
-			logger -s -t "ffac-ssid-changer" -p 5 $MSG"SSID is $CURRENT_SSID, change to $ONLINE_SSID"
-			sed -i "s~^ssid=$CURRENT_SSID~ssid=$ONLINE_SSID~" $HOSTAPD
+			logger -s -t "ffac-ssid-changer" -p 5 "$MSG""SSID is $CURRENT_SSID, change to $ONLINE_SSID"
+			sed -i "s~^ssid=$CURRENT_SSID~ssid=$ONLINE_SSID~" "$HOSTAPD"
 			# HUP here would be to early for dualband devices
 			HUP_NEEDED=1
 		else
 			logger -s -t "ffac-ssid-changer" -p 5 "could not set to online state: did neither find SSID '$ONLINE_SSID' nor '$OFFLINE_SSID'. Please reboot"
 		fi
 		if [ "$OWE" = true ]; then
-			CURRENT_SSID_OWE="$(grep "^ssid=$OFFLINE_SSID_OWE" $HOSTAPD | cut -d"=" -f2)"
+			CURRENT_SSID_OWE="$(grep "^ssid=$OFFLINE_SSID_OWE" "$HOSTAPD" | cut -d"=" -f2)"
 			if [ "$CURRENT_SSID_OWE" = "$OFFLINE_SSID_OWE" ]; then
 				# set online
-				logger -s -t "ffac-ssid-changer" -p 5 $MSG"OWE SSID is $CURRENT_SSID_OWE, change to $ONLINE_SSID_OWE"
-				sed -i "s~^ssid=$CURRENT_SSID_OWE~ssid=$ONLINE_SSID_OWE~" $HOSTAPD
+				logger -s -t "ffac-ssid-changer" -p 5 "$MSG""OWE SSID is $CURRENT_SSID_OWE, change to $ONLINE_SSID_OWE"
+				sed -i "s~^ssid=$CURRENT_SSID_OWE~ssid=$ONLINE_SSID_OWE~" "$HOSTAPD"
 				# HUP here would be to early for dualband devices
 				HUP_NEEDED=1
 			else
@@ -164,41 +165,41 @@ if [ "$CHECK" -gt 0 ] || [ "$DISABLED" = '1' ]; then
 	done
 elif [ "$CHECK" -eq 0 ]; then
 	log_debug "node is considered offline"
-	if [ $UP -lt $FIRST ] || [ $M -eq 0 ]; then
+	if [ $UP -lt "$FIRST" ] || [ $M -eq 0 ]; then
 		# set SSID offline, only if uptime is less than FIRST or exactly a multiplicative of switch_timeframe
-		if [ $UP -lt $FIRST ]; then
+		if [ $UP -lt "$FIRST" ]; then
 			T=$FIRST
 		else
 			T=$MINUTES
 		fi
 		#echo minute $M, check if $OFF_COUNT is more than half of $T
-		if [ $OFF_COUNT -ge $(($T / 2)) ]; then
+		if [ "$OFF_COUNT" -ge $((T / 2)) ]; then
 			# node was offline more times than half of switch_timeframe (or than $FIRST)
 			LOOP=1
 			for HOSTAPD in /var/run/hostapd-phy*; do
 				[ -e "$HOSTAPD" ] || break  # handle the case of no hostapd-phy* files
-				ONLINE_SSID="$(echo $ONLINE_SSIDs | awk -F '~' -v l=$((LOOP*2)) '{print $l}')"
+				ONLINE_SSID="$(echo "$ONLINE_SSIDs" | awk -F '~' -v l=$((LOOP*2)) '{print $l}')"
 				LOOP=$((LOOP+1))
-				CURRENT_SSID="$(grep "^ssid=$OFFLINE_SSID" $HOSTAPD | cut -d"=" -f2)"
+				CURRENT_SSID="$(grep "^ssid=$OFFLINE_SSID" "$HOSTAPD" | cut -d"=" -f2)"
 				if [ "$CURRENT_SSID" = "$OFFLINE_SSID" ]; then
 					log_debug "SSID $CURRENT_SSID is correct, nothing to do"
 					break
 				fi
-				CURRENT_SSID="$(grep "^ssid=$ONLINE_SSID" $HOSTAPD | cut -d"=" -f2)"
+				CURRENT_SSID="$(grep "^ssid=$ONLINE_SSID" "$HOSTAPD" | cut -d"=" -f2)"
 				if [ "$CURRENT_SSID" = "$ONLINE_SSID" ]; then
 					# set offline
-					logger -s -t "ffac-ssid-changer" -p 5 $MSG"$OFF_COUNT times offline, SSID is $CURRENT_SSID, change to $OFFLINE_SSID"
-					sed -i "s~^ssid=$ONLINE_SSID~ssid=$OFFLINE_SSID~" $HOSTAPD
+					logger -s -t "ffac-ssid-changer" -p 5 "$MSG""$OFF_COUNT times offline, SSID is $CURRENT_SSID, change to $OFFLINE_SSID"
+					sed -i "s~^ssid=$ONLINE_SSID~ssid=$OFFLINE_SSID~" "$HOSTAPD"
 					HUP_NEEDED=1
 				else
 					logger -s -t "ffac-ssid-changer" -p 5 "could not set to offline state: did neither find SSID '$ONLINE_SSID' nor '$OFFLINE_SSID'. Please reboot"
 				fi
 				if [ "$OWE" = true ]; then
-					CURRENT_SSID_OWE="$(grep "^ssid=$OFFLINE_SSID_OWE" $HOSTAPD | cut -d"=" -f2)"
+					CURRENT_SSID_OWE="$(grep "^ssid=$OFFLINE_SSID_OWE" "$HOSTAPD" | cut -d"=" -f2)"
 					if [ "$CURRENT_SSID_OWE" = "$ONLINE_SSID_OWE" ]; then
 						# set offline
-						logger -s -t "ffac-ssid-changer" -p 5 $MSG"$OFF_COUNT times offline, SSID is $CURRENT_SSID_OWE, change to $OFFLINE_SSID_OWE"
-						sed -i "s~^ssid=$ONLINE_SSID_OWE~ssid=$OFFLINE_SSID_OWE~" $HOSTAPD
+						logger -s -t "ffac-ssid-changer" -p 5 "$MSG""$OFF_COUNT times offline, SSID is $CURRENT_SSID_OWE, change to $OFFLINE_SSID_OWE"
+						sed -i "s~^ssid=$ONLINE_SSID_OWE~ssid=$OFFLINE_SSID_OWE~" "$HOSTAPD"
 						HUP_NEEDED=1
 					else
 						logger -s -t "ffac-ssid-changer" -p 5 "could not set to offline state: did neither find SSID '$ONLINE_SSID_OWE' nor '$OFFLINE_SSID_OWE'. Please reboot"
@@ -208,7 +209,7 @@ elif [ "$CHECK" -eq 0 ]; then
 		fi
 		#else echo minute $M, just count $OFF_COUNT
 	fi
-	echo "$(($OFF_COUNT + 1))">$TMP
+	echo "$((OFF_COUNT + 1))">$TMP
 fi
 
 if [ $HUP_NEEDED = 1 ]; then
@@ -217,6 +218,7 @@ if [ $HUP_NEEDED = 1 ]; then
 	## check for nonmachting hotapd-pidfiles
 	if [ -f /lib/gluon/eulenfunk-hotfix/check_hostapd.sh ] ; then
 	   sleep 2 # settle down
+	   # shellcheck disable=SC2009
 	   ps|grep hostapd|grep .pid|xargs -n 10 /lib/gluon/eulenfunk-hotfix/check_hostapd.sh
 	fi
 	HUP_NEEDED=0