/etc/hosts Auto Update BASH Script Based on Dynamic DNS

#!/bin/bash
NEWHOST=`nslookup nuwira.dyndns.org | grep Address | sed '$!d' | sed 's/Address: //'` # getting new IP address
if [[ $NEWHOST != "" ]]; then # check if there's IP address
sed 's/^(.*)apihostname$//' /etc/hosts > /tmp/hosts # delete old entry
sed '$d' /tmp/hosts > /tmp/hosts2 # delete new line, copy to temporary file /tmp/hosts
echo "$NEWHOST apihostname" >> /tmp/hosts2 # write it to temporary file /tmp/hosts2
cp /tmp/hosts2 /etc/hosts # done, copy back to /etc/hosts
rm /tmp/hosts # deleting temporary files
rm /tmp/hosts2
echo "IP address: $NEWHOST" # show the new IP address
fi