- List the current configured remote repository for your fork.
git remote -v
- Specify a new remote upstream repository that will be synced with the fork.
git remote add upstream https://github.com/P2PSP/p2psp.git
- Verify the new upstream repository you've specified for your fork.
git remote -v
- Fetch the branches and their respective commits from the upstream repository. Commits to master will be stored in a local branch, upstream/master.
git fetch upstream
- Check out your fork's local master branch.
git checkout master
Or
git checkout -b gui origin/gui
- Merge the changes from upstream/master into your local master branch. This brings your fork's master branch into sync with the upstream repository, without losing your local changes.
git merge upstream/master
Or
git merge upstream/gui
Reference: https://help.github.com/articles/syncing-a-fork/
git push -u origin gui