diff --git a/back/update_vendors.sh b/back/update_vendors.sh
index ec6aa5c5..7ce6c4f1 100755
--- a/back/update_vendors.sh
+++ b/back/update_vendors.sh
@@ -20,15 +20,15 @@ echo "---------------------------------------------------------"
 
 # ----------------------------------------------------------------------
 echo Updating... /usr/share/ieee-data/
-cd /usr/share/ieee-data/
+cd /usr/share/ieee-data/ || { echo "could not enter /usr/share/ieee-data directory"; exit 1; }
 
 sudo mkdir -p 2_backup
-sudo cp *.txt 2_backup
-sudo cp *.csv 2_backup
+sudo cp -- *.txt 2_backup
+sudo cp -- *.csv 2_backup
 echo ""
 echo Download Start
 echo ""
-sudo curl $1  -LO https://standards-oui.ieee.org/iab/iab.csv \
+sudo curl "$1"  -LO https://standards-oui.ieee.org/iab/iab.csv \
               -LO https://standards-oui.ieee.org/iab/iab.txt \
               -LO https://standards-oui.ieee.org/oui28/mam.csv \
               -LO https://standards-oui.ieee.org/iab/iab.txt \
@@ -44,10 +44,10 @@ echo Download Finished
 # ----------------------------------------------------------------------
 echo ""
 echo Updating... /usr/share/arp-scan/
-cd /usr/share/arp-scan
+cd /usr/share/arp-scan || { echo "could not enter /usr/share/arp-scan directory"; exit 1; }
 
 sudo mkdir -p 2_backup
-sudo cp *.txt 2_backup
+sudo cp -- *.txt 2_backup
 
 # Update from /usb/lib/ieee-data
 sudo get-iab -v
diff --git a/dockerfiles/start.sh b/dockerfiles/start.sh
index 252e6ff5..1c5bc001 100755
--- a/dockerfiles/start.sh
+++ b/dockerfiles/start.sh
@@ -31,7 +31,7 @@ echo "[INSTALL] Run setup scripts"
 
 # Change port number if set
 if [ -n "${PORT}" ]; then  
-  sed -ie 's/listen 20211/listen '${PORT}'/g' /etc/nginx/sites-available/default
+  sed -ie 's/listen 20211/listen '"${PORT}"'/g' /etc/nginx/sites-available/default
 fi 
 
 echo "[INSTALL] Setup NGINX"
@@ -60,7 +60,7 @@ fi
 
 # Change web interface address if set
 if [ -n "${LISTEN_ADDR}" ]; then  
-  sed -ie 's/listen /listen '${LISTEN_ADDR}:'/g' /etc/nginx/conf.d/pialert.conf
+  sed -ie 's/listen /listen '"${LISTEN_ADDR}":'/g' /etc/nginx/conf.d/pialert.conf
 fi
 
 # Run the hardware vendors update at least once
diff --git a/dockerfiles/user-mapping.sh b/dockerfiles/user-mapping.sh
index 40dd4ec2..eeff48bd 100755
--- a/dockerfiles/user-mapping.sh
+++ b/dockerfiles/user-mapping.sh
@@ -9,7 +9,7 @@ if [ -z "${USER}" ]; then
 fi
 
 # if both not set we do not need to do anything
-if [ -z "${HOST_USER_ID}" -a -z "${HOST_USER_GID}" ]; then
+if [ -z "${HOST_USER_ID}" ] && [ -z "${HOST_USER_GID}" ]; then
     echo "Nothing to do here." ; exit 0
 fi
 
@@ -20,20 +20,20 @@ USER_GID=${HOST_USER_GID:=$USER_GID}
 
 LINE=$(grep -F "${USER}" /etc/passwd)
 # replace all ':' with a space and create array
-array=( ${LINE//:/ } )
+array=( "${LINE//:/ }" )
 
 # home is 5th element
 USER_HOME=${array[4]}
 
 # print debug output
-echo  USER_ID  : ${USER_ID};
-echo  USER_GID : ${USER_GID};
-echo  USER_HOME: ${USER_HOME};
-echo  TZ       : ${TZ};
+echo  USER_ID"  ": "${USER_ID}";
+echo  USER_GID : "${USER_GID}";
+echo  USER_HOME: "${USER_HOME}";
+echo  TZ"       ": "${TZ}";
 
 sed -i -e "s/^${USER}:\([^:]*\):[0-9]*:[0-9]*/${USER}:\1:${USER_ID}:${USER_GID}/"  /etc/passwd
 sed -i -e "s/^${USER}:\([^:]*\):[0-9]*/${USER}:\1:${USER_GID}/"  /etc/group
 
-chown -R ${USER_ID}:${USER_GID} ${USER_HOME}
+chown -R "${USER_ID}:${USER_GID} ${USER_HOME}"
 
-exec su - "${USER}"
\ No newline at end of file
+exec su - "${USER}"
diff --git a/install/install.sh b/install/install.sh
index 1e9ccca6..05900535 100755
--- a/install/install.sh
+++ b/install/install.sh
@@ -26,6 +26,10 @@ rm -R $INSTALL_DIR/pialert
 # Clone the application repository
 git clone https://github.com/jokob-sk/Pi.Alert "$INSTALL_DIR/pialert"
 
+# Check for buildtimestamp.txt existence, otherwise create it
+if [ ! -f /home/pi/pialert/front/buildtimestamp.txt ]; then
+  date +%s > /home/pi/pialert/front/buildtimestamp.txt
+fi
 
 # Start PiAlert
 "$INSTALL_DIR/pialert/dockerfiles/start.sh"