Bring a large pot of water to a boil. Liberally salt the water and cook linguine to al dente.
While the pasta cooks, heat olive oil in a large skillet over medium-high heat. Once the pan is hot, add onions and cook until soft, about 2-3 minutes. Add clams, toss to combine, and cook for 2-3 minutes. Add mussels and white wine, and cover the pan to steam the clams and mussels for about 3-4 minutes, or until all the mussels and clams are open. Discard any clams and/or mussels that do not open.