If you reference User directly, your code will not work in projects where the AUTH_USER_MODEL setting has been changed to a different user model. A more generic way to create the user would be:
echo "from django.contrib.auth import get_user_model; User = get_user_model(); User.objects.create_superuser('admin', '[email protected]', 'password')" | python manage.py shell
ORIGINAL ANSWER
Here there is a simple version of the script to create a superuser:
echo "from django.contrib.auth.models import User; User.objects.create_superuser('admin', '[email protected]', 'pass')" | python manage.py shell