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Git-related tips

This file contains various tips and tricks for using the git CLI (and GitHub too!)

Glossary

Some helpful git and GitHub related terms.

Name Abbreviation Description
repository repo A repository is like a folder that holds a project's files, but unlike other folders, a repository is tracked for changes by git
commit - A commit holds the specific changes to files that were made since the last commit
pull request PR Short for "Pull Request", this is a request to merge the changes made on one repository or branch into another repository or branch
branch - A branch is like a new workspace for the same project, allowing you to work on changes, commit them, and push them to a repository without affecting the original branch
fork - A forked repository is a "copy" of a repository that has references to the original. GitHub will track differences between a fork and a source for you, and show the number of different commits
clone - Cloning a repository is the process of bringing the files and configuration from the online/external location to your local machine
remote - A remote repository is a repository stored outside your local computer (so, on GitHub or GitLab for example)
stash - Save the uncommitted work locally

Rebasing a Fork

You'll likely run in to situations where your forked version of a project "falls behind" the state of the source version. GitHub will allow you to make a pull request to bring the changes from the source into your fork, which does work, but creates a merge commit that will show up every time you create a PR back to the source.

Instead, to keep the commit history clean, you can rebase your fork against the source. Here are the steps to do so:

  • Step one: Make sure you are on your primary branch with git checkout <branchname>. Most commonly, this will be git checkout main.
  • Step two: Get the current state of the source repository with git fetch upstream. If it throws an error that there is no upstream, you'll need to set it ↓
    • Step two.five: To set the upstream, you'll use git remote add upstream <url>, where the URL is the clone URL for the source repository.
  • Step three: Reset the state of your local repository to match the source with git reset --hard upstream/<branchname>, where branchname is the name of the primary branch. So, most likely git reset --hard upstream/main.
  • Step four: Force your fork repo to match this new state with git push -f.
  • Step five: Celebrate your success!

Rebasing a PR

Sometimes you end up with merge conflicts in your pull request, because the target repository has had changes that do not mesh with your changes. GitHub offers a handy GUI for fixing merge conflicts, but this is only available for "non-complex" merge conflicts. If this GUI is not available, you can follow these steps to rebase your PR against the base branch of the fork and resolve the merge conflicts.

  • Step one: Make sure you are on the branch you used for that pull request with git checkout <branchname>.
  • Step two: Get the current state of the source repository with git fetch upstream.If it throws an error that there is no upstream, you'll need to set it ↓
    • Step two.five: To set the upstream, you'll use git remote add upstream <url>, where the URL is the clone URL for the source repository.
  • Step three: Trigger the interactive rebase flow with git rebase -i upstream/branchname where "branchname" is the name of the default/primary branch (most likely main.)
  • Step four: Using the file that your editor opens up, ensure that all commits are marked as pick (they should be, by default.) Save and close the file.
  • Step five: Your editor and git will now walk you through each commit that generates a merge conflict. Adjust the files, choosing which version of changes you want to keep. Make sure you remove the <<<<<, >>>>>, and ===== that git adds to show the conflicts!
  • Step six: As you fix each file, you will need to git add <filename> and git commit to commit the resolved changes.
  • Step seven: Once all conflicts are resolved, git will allow you to git push those changes. Your PR should automatically update and reflect the new state, with no merge conflicts!
  • Step eight: Celebrate your success! Merge conflicts can definitely be tricky!

Squashing Your Commits

A maintainer might have a contributing requirement that PRs have only one commit, or they might ask you to squash your PR's commits into one. These steps will help you do so!

  • Step one: Make sure you are on the branch you used for that pull request with git checkout <branchname>.
  • Step two: Using git's interactive rebasing feature, we are going to rebase against your current default branch with git rebase -i origin/<branchname> (the branch name is most likely main).
  • Step three: Using the file that opens in your editor, set the commit at the top of the list to pick and the rest of the commits to squash. Save and close the file.
  • Step four: Force your remote branch to accept this new commit history with git push -f.
  • Step five: Celebrate your success! 🎉

Note: Force-pushing a branch can have unintended side effects, so be very careful when force-pushing.

Squashing the latest commit

If you want to squash the latest commit only, you can run one single command which is much shorter.

  1. Be sure to verify that you're on the correct branch.
  2. Stage all your changes by using git add . or git add <filename> for certain file.
  3. Run the following command. This command will squash the current staged changes with the other commit's changes.
git commit --amend -m "commit message" -m "commit description (optional)"
  1. Force-push your changes to the desired branch.
git push -f
  1. You're done now! 🎉 The latest commit has been successfully changed.