diff --git a/README.md b/README.md
index 6ce55d5..5376f53 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,11 @@
 
 Dynamic DNS updates for UnitedDomains and Vodafone EasyBox
 
+## Prerequisites
+```
+apk add bash bind-tools wget curl libxml2-utils jq
+```
+
 
 ## Credits
 
diff --git a/ddns.sh b/ddns.sh
index 5a72849..d31b1ef 100755
--- a/ddns.sh
+++ b/ddns.sh
@@ -7,6 +7,19 @@ NAMESERVER="1.1.1.1"
 
 # ----- END CONFIG -------------------------------
 
+
+COMMANDS="dirname cat dig"
+for COMMAND in $COMMANDS; do
+  if ! command -v $COMMAND &> /dev/null
+  then
+    echo "$COMMAND could not be found!"
+    exit 1
+  fi
+done
+
+set -e
+
+
 SCRIPTPATH="$( cd "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
 
 DOMAIN="$1"
diff --git a/easyBoxCtrl.sh b/easyBoxCtrl.sh
index d0bd8fc..88cf215 100755
--- a/easyBoxCtrl.sh
+++ b/easyBoxCtrl.sh
@@ -31,6 +31,16 @@ WGET="/usr/bin/wget ${WGET_OPTS[@]}"
 
 # * * * NO MORE CHANGES DOWN HERE * * * 
 
+COMMANDS="wget curl grep awk sed"
+for COMMAND in $COMMANDS; do
+  if ! command -v $COMMAND &> /dev/null
+  then
+    echo "$COMMAND could not be found!"
+    exit 1
+  fi
+done
+
+
 RETVAL=""
 touch $COOKIEFILE
 
diff --git a/unitedDomainsCtrl.sh b/unitedDomainsCtrl.sh
index 79a721c..fe864a4 100755
--- a/unitedDomainsCtrl.sh
+++ b/unitedDomainsCtrl.sh
@@ -16,6 +16,14 @@ UA="Mozilla/5.0 (X11; Ubuntu; Linux x86_64) Gecko/20100101 Firefox"
 
 # * * * NO MORE CHANGES DOWN HERE * * * 
 
+COMMANDS="sed wget grep jq"
+for COMMAND in $COMMANDS; do
+  if ! command -v $COMMAND &> /dev/null
+  then
+    echo "$COMMAND could not be found!"
+    exit 1
+  fi
+done
 
 # parse parameters
 DOMAIN=$(echo $1 | sed -r 's/^.*\.(.+\..+)$/\1/')
@@ -39,11 +47,11 @@ OUT=$(wget -U "$UA" \
 	--keep-session-cookies \
 	-qO- "https://www.united-domains.de/login/")
 
-CSRF=$(echo "$OUT" | /bin/grep -oP -m 2 "(?<=<input type=\"hidden\" name=\"csrf\" value=\")[^\"]*(?=\"( /)?>)" | tail -1)
+CSRF=$(echo "$OUT" | grep -oP -m 2 "(?<=<input type=\"hidden\" name=\"csrf\" value=\")[^\"]*(?=\"( /)?>)" | tail -1)
 echo "CSRF=${CSRF}"
-CSRFMETA=$(echo "$OUT" | /bin/grep -oP -m 1 "(?<=<meta name=\"csrf\" content=\")[^\"]*(?=\"( /)?>)")
+CSRFMETA=$(echo "$OUT" | grep -oP -m 1 "(?<=<meta name=\"csrf\" content=\")[^\"]*(?=\"( /)?>)")
 echo "CSRFMETA=${CSRFMETA}"
-CSRFSCRIPT=$(echo "$OUT" | /bin/grep -oP -m 1 "(?<=\"CSRF_TOKEN\":\")[^\"]*(?=\")")
+CSRFSCRIPT=$(echo "$OUT" | grep -oP -m 1 "(?<=\"CSRF_TOKEN\":\")[^\"]*(?=\")")
 echo "CSRFSCRIPT=${CSRFSCRIPT}"
 
 wget -U "$UA" \
@@ -120,7 +128,7 @@ echo "NEW: $record"
 #    --keep-session-cookies \
 #    -qO- "https://www.united-domains.de/portfolio/a/domain-admin/dns/$DOMAIN_ID")
 
-#csrfscript=$(echo "$loginpage" | /bin/grep -oP -m 1 "(?<=\"CSRF_TOKEN\":\")[^\"]*(?=\")")
+#csrfscript=$(echo "$loginpage" | grep -oP -m 1 "(?<=\"CSRF_TOKEN\":\")[^\"]*(?=\")")
 #echo "csrfscript=${csrfscript}"
 
 
@@ -145,7 +153,7 @@ OUT=$(wget -U " $UA" \
     -O- "https://www.united-domains.de/pfapi/dns/domain/$DOMAIN_ID/records" 2>&1)
 #echo "UD answered: $OUT"
 
-#echo $OUT | /bin/grep "$IPV4" >/dev/null 2>&1
+#echo $OUT | grep "$IPV4" >/dev/null 2>&1
 
 SUCCESS=$?
 echo "Retval: $SUCCESS"