Cutting Nails During Shiva

Is it permitted for a mourner to cut nails during the shiva?

A mourner is prohibited from cutting nails with a tool during the seven and thirty days. However, it is permitted to cut them with one's teeth or mouth.

Gemara Moed Katan, page 17b: "The Rabbis taught: Just as it is forbidden to shave during the festival, so it is forbidden to cut nails during the festival, according to Rabbi Yehuda. Rabbi Yossi permits it. And just as it is said: A mourner is forbidden to shave during the days of mourning, so it is forbidden to cut nails during the days of mourning, according to Rabbi Yehuda. Rabbi Yossi permits it. Ulla said: The law is according to Rabbi Yehuda in mourning, Shmuel said, the law is according to Rabbi Yossi in the festival and in mourning. As Shmuel said: The law follows the lenient opinion in mourning. Pinchas, the brother of Mar Shmuel, had a misfortune (a relative passed away), Shmuel came to ask him the reason. He saw his nails were long, he said to him: Why didn't you cut them? - He said to him: If it were you, would you neglect it so much? It was like a mistake that came from the ruler, and a misfortune happened to Shmuel (a relative of Shmuel passed away). Pinchas, the brother, came to ask him the reason, he cut his nails and threw them in his face, he said to him: Do you not have a covenant made with the lips? As Rabbi Yochanan said: From where do we know that a covenant is made with the lips - as it is said, and Abraham said to his young men: Stay here with the donkey, and I and the lad will go yonder and worship and return to you, and the matter was successful, and both returned. They thought: by hand - yes, by foot - no. Rav Anan bar Tachlifa said: It was explained to me by Shmuel: there is no difference, by hand or by foot. Rav Chiya bar Ashi said in the name of Rav: And in a gnustra it is forbidden. Rav Shimon bar Abba said: I was standing before Rabbi Yochanan in the study house during the intermediate days of the festival, and he cut his nails with his teeth and threw them. Tosafot wrote there that it is permitted to cut nails by change with teeth or with hands one against the other, and from the case of Shmuel it is implied that even during the days of shiva it is permitted to cut nails by change, since Shmuel asked Pinchas about his long nails, and presumably it was during shiva, and it is also likely that Pinchas came to Shmuel during shiva. And so ruled the Shulchan Aruch, Siman 390, paragraph 7: "Just as it is forbidden to shave all thirty days, so it is forbidden to cut nails with a tool; but with hands or teeth, it is permitted, even during the seven days."