Keep a github/gitlab fork up-to-date

Manage your forks

If you forked a github or gitlab repository to propose pull/merge requests, you may need to work on the last updated version of the original repository. The graphical interfaces do not allow you to stay up-to-date with the exact same commits. If you already tried graphically, you probably had to include different merge commits.
Hence, to be able to continue participate in the development, or get your own fork updated with the last modifications of the original repository, you will have to manage this locally with a few command lines. All command lines below are to be run in a Terminal. Remember that you have a “Terminal” interface in your Rstudio IDE to manage your system using command lines.

Figure 1: From https://happygitwithr.com

# List distant connections
git remote -v
# Add upstream
git remote add upstream https://github.com/ThinkR-open/attachment.git
# List distant connections to verify upstream has been added
git remote -v
# Retrieve commits of the upstream
git fetch upstream

# Create a branch named upstream_master and open it
git checkout -b upstream_master upstream/master
# Update its content
git pull

# old git version
# git branch --set-upstream=upstream/master upstream_master
# new git version
git branch --set-upstream-to=upstream/master upstream_master

git checkout my-branch
git pull
git rebase upstream_master
# or directly from (local) distant
git rebase upstream/master

git checkout my-branch
git pull
git merge upstream_master

Manage your branches

With multiple developers working on the same project, you can adopt a similar behaviour with your main branch (being master or dev depending on your git architecture choices).

My personnal behaviour is:

• Work locally

• rebase each time the repository manager informs me that the main branch has been updated, in order to reduce conflicts resolutions

  # be sure to be on your branch
  git checkout my-branch
  # update the local-distant server part
  git fetch
  # Stash your current work
  git stash
  # Rebase if you know what your are doing
  git rebase origin/dev
  # Un-stash your current work and solve potential conflicts
  git stash apply

• Send to the server only when I want my work to be merged to the main branch:

  # git add your-files
  # git commit your changes
  # Push to distant server
  git push

• Open a pull/merge request to inform other developers and the manager of your modifications

I know that this behaviour is not viable for all git projects, but if it can give you ideas, it will already be that of shared. Then you can compare to other git projects management.

This short blog post is more a reminder to me, so that I know where to find the information quickly. If you want to know more on git, in particular when developing in R, I would recommend https://happygitwithr.com. In fact, there is also a chapter on forking: https://happygitwithr.com/upstream-changes.html