How to update a submodule in git?

Question

git

There is project A and there is project B, which contains a submodule (project A with commit X).
Project A received a bunch of commits. In project B, in the submodule, of course, nothing was updated
How to update the submodule in project B?

Answer 1

I advise you to read Pro Git progit.org
Specifically, the chapter on submodules is progit.org/book/ru/ch5-8.html

Answer 2

The question is removed, the answer, after a long googling, is found.
cd submodule
git pull origin master
cd -