Updates Git. Always stay on master branch. Install Git from source. Clone git/git repository from GitHub. Install Git from cloned repo. Remove old version of Git.

git-update.sh

#!/usr/bin/env bash

prefix=~/opt

function compile {
    make clean
    make prefix=${prefix}
    make prefix=${prefix} install
}

cd master
git checkout master -q
git clean -dxfq
git pull | grep  "Already up-to-date" || compile