git: programmatically know by how much the branch is ahead/behind a remote branch

Question

I would like to extract the information that is printed after a git status, which looks like:

# On branch master
# Your branch is ahead of \'origin/         


        

Answer 1

Why wouldn't this work:

#!/bin/sh
git diff origin/master..HEAD --quiet --exit-code
RETVAL=$?
if [ $RETVAL -gt 0 ]; then
    echo "You need to git push!"
else
    echo "No git push necessary!"
fi