Check if domain name is subdomain

bash

# Check if domain is subdomain
if [[ -n $domain ]]; then
	count=1
	while true; do
		tld=$(echo "${domain}" | rev | cut -d'.' -f -$count -s | rev)
		if ! grep -Fxq "$tld" /opt/webinoly/lib/public_suffix_list.dat; then
			break
		fi
		count=$[$count+1]
	done
	[[ -n $(echo "$(echo "${domain}" | rev | cut -d'.' -f $count- -s | rev)" | cut -d'.' -f 2 -s) || $count == 1 ]] && echo "Is subdomain" || echo "Not subdomain"
fi

public_suffix_list.dat

# Obtain the full list from here: https://publicsuffix.org - needed to recognize only valid TLD's.
com
com.mx
mx
gov
org
net
edu