Cook the pasta in 3-4 l boiling salted water (1 teaspoon salt per litre) according to the instructions on the packet. Peel and finely chop onion and garlic. Fry sausage in hot oil, remove. Sauté onion and garlic in frying fat.
Add the tomatoes, season with salt, pepper and sugar. Bring to the boil and simmer for about 5 minutes.
Chop the olives finely. Wash the basil, remove the leaves. Stir both into the sauce with sausage. Drain the pasta, mix with the sauce and serve.