Discard any clams that do not close to the touch. In a large sauté pan, combine the clams and white wine. Place over high heat, cover and steam, shaking the pan occasionally, until the clams open, 3 to 4 minutes for Manila clams or 5 to 7 minutes for larger clams. Using a slotted spoon, transfer the clams to a shallow bowl. Discard any clams that failed to open. Line a fine-mesh sieve with cheesecloth, place over a bowl and strain the pan juices. If using small clams, you may leave them in their shells or remove them, but leave them whole. If the clams are large, let them cool until they can be handled, then remove the meat from the shells, capturing any juices. Chop the clams into bite-size pieces, place in a bowl and pour the strained juices over them. Then, pour any captured juices through the lined sieve held over the bowl containing the clams.
Bring a large pot three-fourths full of salted water to a boil over high heat. Add the pasta, stir well and cook until al dente (tender but firm to the bite), about 10 minutes or according to the package instructions.
Meanwhile, in the same sauté pan over low heat, warm the olive oil. Add the garlic, oregano and red pepper flakes and sauté until warmed through, 1 to 2 minutes.
Add the clams and their juices and heat through gently. Do not overcook or the clams will toughen. Add the parsley and a generous amount of black pepper. Season with salt if the clams are not salty enough, then swirl in the butter.
Drain the linguine and transfer to a warmed serving bowl. Add the clam sauce and toss well.