Peel and halve the onion and cut into fine strips. Peel off the garlic clove and cut into fine slices. Halve the cherry tomatoes. Chop the parsley. Salt the boiling pasta water and cook the linguine al dente in it. In the meantime, heat the olive oil in a saucepan. Sauté the onions and garlic in it over a medium heat for 2 minutes. Add tomatoes, sugar and 3 tablespoons of pasta boiling water and cook for 5 minutes. Mix the olives, capers and parsley into the tomatoes. Season with a little salt and pepper. Drain the pasta and mix immediately with the tomato sauce. Serve sprinkled with finely grated Italian hard cheese.