#!/bin/bash

dialog --inputbox "Enter your name:n" 8 40 2>/var/lib/bla/name;
dialog --inputbox "Enter your email address:n" 8 40 2>/var/lib/bla/email;

if [ -s /var/lib/bla/name ] && [ -s /var/lib/bla/email ]; then
    echo "Awesome."
    exit 0

else
    /etc/profile.d/credentials.sh
fi