SHELL

rebase my fork branch

git checkout master # Make sure you are in master
git remote add author original_repo_that_you_forked_from
    # Note: This is in the format git@github.com:authors_name/repo_name.git
    #       Only needs definition once, future fetches then use it. 
git fetch author
git status # make sure you are in the master branch for the following merge
git merge author/master  # i.e. 'into' your master branch
git checkout your-branch
git rebase master        # Now get those changes into your branch.
git push origin your_branch # You can also use `-f` if necessary and `--all`

rebase forked branch with master

# Add the remote, call it "upstream":

git remote add upstream https://github.com/whoever/whatever.git

# Fetch all the branches of that remote into remote-tracking branches

git fetch upstream

# Make sure that you're on your master branch:

git checkout master

# Rewrite your master branch so that any commits of yours that
# aren't already in upstream/master are replayed on top of that
# other branch:

git rebase upstream/master