原文：https://robots.thoughtbot.com/keeping-a-github-fork-updated
I forked a GitHub repo thoughtbot/dotfiles to croaky/dotfiles and want to keep it updated.
After I forked the repo to your Github account, I did this one time:
git clone git@github.com:croaky/dotfiles.git
cd dotfiles
git remote add upstream git@github.com:thoughtbot/dotfiles.git
Each time I want to update, from my local master branch:
git fetch upstream
git rebase upstream/master
The goal of the rebase is to have a cleaner history if I have local changes or commits on the repo. It’s the difference between the the left and the right in the image below.
If I also have commit rights to the upstream repo, I can create a local upstream branch and do work that will go upstream there.
git checkout -b upstream upstream/master
原文：http://www.cnblogs.com/wuyahuang/p/4512960.html