#   handle unexpected exceptions (default bahaviour), RSA key
# + fingerprint not found and authentication password request
#
expect {

          default { 
             send_user "unable to connect to host $host\r\n"
             exit $ec_exception
          }

          -re ".*Are.*.*yes.*no.*" {
             send -s "yes\r"
             exp_continue
             #look for the password prompt
          }

          "assword:" {
             send -s "$password\r"
             #the expect command will now return
          }

}

#   handle the chance that the password is not valid or access is denied
expect { 

         default {
            send_user "unable to connect to host $host\r\n"
            exit $ec_exception
         }

         -re "denied|failed|invalid|incorrect" {
            send_user "invalid password or account for host $host\r\n"
            exit $ec_failedauth
         }

         "$shell_prompt"

}

            exit $ec_exception

            exit $ec_failedauth

for ip in `cat iplist.txt`
do
   /home/user1/script/change.sh $ip
   RETVAL=$?
   if [ $RETVAL -ne 0 ] ; then
      #perform some action based on intercepted exit code (i.e. log a message, send an email, etc.)...
      [...]
   fi
done