Shell Programming and Scripting

#!/bin/bash
while [ answer != "0" ]
do
clear
echo ""
echo " 1. use 10.1.1.27"
echo " 2. use 10.1.2.27"
echo " 3. show config file"
echo " 0. exit"
echo ""
read -p " -> " answer
    case $answer in
       0) break ;;
       1) echo "Domain.com smtp:10.1.1.27" > /etc/postfix/transport && 
          echo "" && echo "config file was updated!" ;;
       2) echo "Domain.com smtp:10.1.2.27" > /etc/postfix/transport &&
          echo "" && echo "config file was updated!" ;;
       3) echo "" && cat /etc/postfix/transport ;;
   esac
   echo ""
   echo "press RETURN for continue"
   read key
done
exit 0