CNAME (alias) Check for Domain/-s via Bash Script

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#!/bin/bash
#set -x

print_usage() {
  printf "Usage: aliastest.sh -a alis-domain.tld -d domain.tld domain2.tld" 
}

# Get the options
while getopts ":h:a:d:" option; do
   case $option in
      h) # display Help
         print_usage
         exit;;
      a) # The alias hostname for check
         hostname=$OPTARG
         ;;
      d) # Domain or domains
         domains=$OPTARG
         ;;
   esac
done

for domain in $domains
do
        echo "Check for $domain:" 
        echo "-------------------" 
        CNAME=$(dig +short CNAME $domain)
        if [ "${CNAME}" == "${hostname}." ]; then
                echo "$domain is alias for $hostname" 
        else
                echo "$domain is NOT alias for $hostname" 

        fi
done