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

Heres a copy-paste solution which works inside the repository.

origin_head=$(git ls-remote --heads $(git config --get remote.origin.url) | grep "refs/heads/master" | cut -f 1)
if [ $origin_head != "$(git rev-parse HEAD)" ]; then
    echo >&2 "HEAD and origin/master differ."
    exit 1
fi