Log dynamic dns records

log_dynamic_dns.sh

#!/bin/bash

# first A record, second authoritive DNS
RECORDS=(example.com ns.example.com mustermann.de ns.google.de)
LOGPATH="/var/log/iplog"
COUNTER=1

for RECORD in ${RECORDS[@]}; do
	if [[ ! $(($COUNTER % 2)) -eq 0 ]]; then
		DOMAIN=$RECORD
	else
		NS=$RECORD
		IP=$(dig +noall +answer @$NS $DOMAIN | awk '{print $NF}')
		if [[ ! $IP =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
			continue
		fi
		DOMAINLOG=$(echo $DOMAIN | tr '.' '-')
		LOG="$LOGPATH/$DOMAINLOG.log"
		LASTENTRY=$(tail -n1 $LOG | grep $IP)
		if [[ $? -eq 0 ]]; then
			echo "$DOMAIN didn't change"
		else
			if [[ ! -d $LOGPATH ]]; then
				mkdir $LOGPATH
			fi
			echo "$(date +%F-%T) $DOMAIN $IP" | tee -a $LOG
		fi
	fi

	COUNTER=$(($COUNTER + 1))
done