How to get SHA of the latest commit from remote git repository?

Question

Does anyone know how to get the latest SHA of a given branch from outside a git repository?

If you are inside a git repository, you can do:

Answer 1

Using a git URL:

$ git ls-remote  | head -1 | sed "s/HEAD//"

Using a directory on an accessible system:

$ git --git-dir=/path/to/repo/.git rev-parse origin/