adds rudimentary command checks + documents packages to install for alpine

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"