Shell Programming and Scripting

I am trying to set up prompts when you don't enter the right information or dont enter the information at all, when executing a script. Below is the question that i am asking and i am not sure how to set up the if statements to make sure that the user enters the name, cpu's, memory and ip. I was told that getopts with a cease statement might be usefull, but im not sure how to apply it. Any help would be greatly appreciated...

NAME=$1
NCPUS=$2
MEMORY=$3
IP=$4
MACHINENAME=`hostname`
MASTERHOST=svvnyc702

echo "Do you wish to proceed with the creation of UAT ZONE zone-${NAME}, CPU's ${NCPUS}, MEMORY ${MEMORY}, IP ${IP}
<y or n> ? \c"
read WISH
echo
if [ $WISH = "n" ] ; then
echo "You chose no, good bye"
exit
fi
if [ ! $WISH = "y" ] ; then
echo in vaild optin g - exiting
exit
fi

here is how you do it,

a,b,c are the command line options

Code:

while
      getopts a:b:c: OPT 2>/dev/null
   do
      case $OPT in
         a)
            VarA=$OPTARG
         ;;
         b)
            VarB=$OPTARG
         ;;
         c) 
            VarC=$OPTARG
         ;;
         *)
            help #Call help function
         ;;
      esac
   done

Please put code inside [code] tags.

Code:

while [ -z "$name" ] ## I recommend using lowercase variable names
do
  printf "Enter NAME: "
  read name
done

while [ -z "$ncpus" ]
do
  printf "Enter number of CPUs: "
  read ncpus
done

while [ -z "$memory" ]
do
  printf "Enter memory: "
  read memory
done

Code:

read wish
case $wish in
   n) echo "You chose no, good bye"
      exit ;;
esac

thanx for the help...