No, a porcupine cannot shoot out its quills at other animals or human beings. But don't go too close to a porcupine. It may switch you with its tail. The tail, like the body, is covered with quills that stick when they touch anything soft.
Each quill has a sharp point. It can easily go into the mouth or tongue of a foolish bear or mountain lion. Once the quill is in, it clings with a sharp barb, like the barb on a fishhook. Often the quill keeps working its way deeper and deeper into the flesh. Although it is no bigger than a toothpick, it can kill a huge bear. A bear can't use pliers as you can to pull the quill out.
