'Shall' in the Bible

So they said to him, "What shall we do to you so that the sea may quiet down for us?" because the sea {was growing more and more tempestuous}.

And he had a proclamation made, and said, "In Nineveh, by a decree of the king and his nobles: "No human being or animal, no herd or flock, shall taste anything! They must not eat, and they must not drink water!