Cook garlic and red pepper flakes in oil in a deep 12-inch heavy skillet over moderate heat, stirring, until fragrant but not browned, about 2 minutes. Add tomatoes with puree, tomato paste, herbs, capers, olives, and wine and simmer, uncovered, stirring occasionally and breaking up tomatoes, until sauce is thick, about 15 minutes.
Cook linguine in a 6 to 8-quart pot of boiling salted water until al dente, then drain in a colander.
While pasta cooks, increase heat under sauce to moderately high and add mussels, then cook, covered, until mussels just open wide, checking frequently after 3 minutes and transferring to a bowl. (Discard any mussels that remain unopened after 6 minutes.)
Serve linguine with mussels and sauce and garnish with chives.
Cooks' Note: Just before cooking, clean mussels by scrubbing them well with a brush under cold water and scraping off any barnacles with a knife. If beard is still attached, remove it by pulling it from tip to hinge or by pulling and cutting it off with knife. The tomato sauce, without mussels, can be made 2 days ahead and chilled, covered.