ec2 rename from tag

gistfile1.sh

#!/bin/bash

REGION=$(curl -s http://169.254.169.254/latest/dynamic/instance-identity/document | grep region | awk -F\" '{print $4}')
FQDN=$(aws ec2 describe-tags --region $REGION --filters "Name=resource-id,Values=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)" "Name=key,Values=Name" --query Tags[].Value --output text)
HOSTNAME=$(echo $FQDN | cut -d. -f1)
IPADDRESS=$(curl -s http://169.254.169.254/latest/meta-data/local-ipv4)

if [ -z "$HOSTNAME" ]; then
    echo "You forgot to set Hostname in Tag Name."
    exit 0
fi

echo $HOSTNAME > /etc/hostname
hostname $HOSTNAME

cat > /etc/hosts << EOF
127.0.0.1 	localhost.localdomain localhost smtp
$IPADDRESS	$FQDN	$HOSTNAME
EOF