get_selection ()
{
count1=1
while [ $count1 = 1 ];
do
echo "enter user or service or item user|service|item :"
read entry
echo entry is $entry
#   if [ -z "$entry" ] || [ $entry != "user" ] || [ $entry != "service" ] || [ $entry!= "item" ]; then
if [ -z "$entry" ] || [ $entry != "user" ] || [  $entry != "service" ]; then
echo "blank or incorrrect entry"
else
echo "entry is correct "
count1=$(( $count1 + 1 ))
fi
done
}

get_selection ()
{
   count1=1
   while [ $count1 = 1 ]; do
      echo "enter user or service or item user|service|item :"
      read entry
      echo entry is $entry

      if [[ -z "$entry" ]] || [[ ! $entry =~ (user|service|item) ]]; then
         echo "blank or incorrrect entry"
      else
         echo "entry is correct "
         count1=$(( $count1 + 1 ))
      fi
   done
}

get_selection ()
{
   count1=1
   while [ $count1 = 1 ]; do
      echo "enter user or service or item user|service|item :"
      read entry
      echo entry is $entry

      case $entry in
         user|service|item)
               echo "entry is correct "
               count1=$(( $count1 + 1 ))
               break
               ;;
         *)
               echo "blank or incorrrect entry"
      esac

   done
}

if [ -z "$entry" ] || { [ "$entry" != "user" ] && [ "$entry" != "service" ]; }; then

get_selection () {
    while true; do
       echo "Enter user or service or item: "
       read entry
       case $entry in
           "") echo "blank entry" ;;
           user|service|item) echo "entry is correct"; break; ;;
           * ) echo "incorrect entry" ;;
       esac
    done
}

select entry in user service item; do
done

if [[ ! ($entry == "user" || $entry == "service") ]]; then
  echo "blank or incorrrect entry"
else
  echo "entry is correct "
fi