Heat oil over medium heat in a large skillet and a small saucepot. To both, add garlic and cook 1 minute. Add calamari to the skillet and cook 2 minutes. Then to both, add pasta sauce and crushed red pepper flakes and bring to a simmer. Simmer 3 to 5 minutes, until calamari is tender. Reserve tomato sauce in the saucepot for another meal.
Transfer linguine to a serving platter. Spoon all of the calamari and tomato sauce over linguine. Garnish with basil, if desired.