• How to think in terms of projects
• File and folder organisation tips
• Git installation (brew install git)
• Git configuration
  • git config --global user.name "Your Name"
  • git config --global user.email your@email.com
• Creating and init(ialising) repositories
• How to add and commit changes
• Viewing commit history with git log
• How to use git checkout to go back in time
• Checking repository status with git status

Today we will cover

• How to push and pull changes to and from remote repositories
• How to use .gitignore to avoid tracking certain files
• Creating and managing branches
• How to clone and fork repositories on GitHub
• Syncing forked repositories on GitHub
• How to create issues and pull requests on GitHub
• Other cool GitHub features, such as Gists, Pages, Actions, and CLI
• If time allows, we will also see what GitHub Copilot does

• Last class, we learned how to add and commit changes
• But what if we want to share our changes with others? 🤔
• There are two main ways to do this:
  • push changes to a remote repository (upload)
  • pull changes from a remote repository (download)
• To push changes to a remote repository, use the command git push
• And to pull changes, use the command git pull

• Why do we need to add a remote repository?
• Because we need to tell Git where to push our changes!
• git remote add origin https://github.com/danilofreire/my-project.git:
  • remote: tells Git we are adding a remote repository
  • add: adds a new remote repository
  • origin: the name of the remote repository
  • https://github.com/danilofreire/my-project.git is the URL of the remote repository
• git branch -M master: renames the branch to master
• git push -u origin master: pushes the changes to the remote repository

• To push further changes to the remote repository, you just repeat the process:
  • git add file-name
  • git commit -m "Message"
  • git push (no need to add the remote repository again)
• If you work by yourself on your computer only, you already know everything you need to know about Git and you can go home now 😂
• Just kidding! There is still a lot to learn!
• If you work with others, or if you use different computers, you need to know how to pull changes from GitHub

• To pull changes from a remote repository, use (you’ve guessed it) the command git pull
• git pull is the equivalent of git fetch + git merge
  • git fetch downloads the changes from the remote repository
  • git merge merges the changes with your local repository
• Let’s see an example where I add a commit directly on GitHub
• I will add a .gitignore file to ignore certain files and directories

• I will go to my repository on GitHub and click on Add file > Create new file

• After adding the file, I will commit the changes

• About .gitignore:

  • It is a file that tells Git which files to ignore
  • You can use wildcards, such as *.csv, to ignore all CSV files
  • You can also ignore entire directories, such as data/
  • You can also ignore files by name, such as secrets.txt

• What if both my coauthors and I change the same line of code?
• If you change different files or lines in the same file, Git will merge the changes automatically 👍
• But if you change the same line of code, Git will not know what to do and will ask you to resolve the conflict
• You can use a tool like git mergetool to help you resolve the conflict
• Or you can open the file in a text editor and resolve the conflict manually

• Let me change the .gitignore file both in my computer and on GitHub, and commit the changes (do not push yet)

• I’ve changed the same line of code on GitHub

• Let’s see what happens if I try to pull the changes to my local computer

• Oh no! 😱

• To resolve the conflict, you need to open the file in a text editor

• You will see the changes from both you and your coauthor (or yourself)

• You can choose which changes to keep, or you can keep both changes

• After resolving the conflict, you need to add the file and commit the changes

• Then you can push the changes to GitHub

• The line that starts with <<<<<<< is your changes

• ======= indicates the end of your changes and the start of your coauthor’s changes

• The line that starts with >>>>>>> is the end of the changes from your coauthor and the commit hash

• I will delete some lines and keep the changes from my computer

• Now the conflict is resolved! 🥳

• There are other ways to resolve conflicts, such as using git mergetool
• You can also use a graphical tool, such as Sourcetree or GitHub Desktop
• But it is good to know how to resolve conflicts manually 😊

• Branches are a way to work on different features or versions of your project
• The master (or main) branch is the default branch in Git on your computer and on GitHub
• However, you can create new branches to work on new features or versions without affecting the master branch
• You can create a new branch with the command git branch branch-name
• And you can switch to the new branch with the command git checkout branch-name
  • Or you can use git switch branch-name if you have Git 2.23 or later
• You can also create a new branch and switch to it with the command git checkout -b branch-name

• Branches may or may not be merged back to the master branch
• You can also delete branches after merging them

• Let’s create a new branch called feature-1
  • git checkout -b feature-1
• I will add a new file called feature-1.txt to the new branch
  • echo "This is feature 1" > feature-1.txt
• Then, I will add, commit, and push the changes to GitHub
  • git add feature-1.txt && git commit -m "Add feature 1"
  • git push origin feature-1 (you need to push the new branch to GitHub)

• Now the branch is already on GitHub

• Let’s merge the changes to the master branch

  • git checkout master
  • git merge feature-1
  • git push

• Done! 🎉 Let’s see what happened

• You can delete the branch with git branch -d feature-1

• To delete the branch on GitHub, use git push origin --delete feature-1

• Cloning is the process of downloading a repository from GitHub to your computer
• You can clone your own repositories or other people’s repositories
• To clone a repository, use the command git clone https://github.com/username/repository-name.git
  • For instance, git clone https://github.com/danilofreire/my-project.git
• Cloning a repository will create a new folder with the repository name
• Your copy will be directly connected to the original repository
• Which means that, if the repository is not yours, you cannot push changes to it
• Mostly used when you have push rights and want to work on a project locally

• Cloning the my-project repository to a different folder

• Forking is the process of creating your copy of a repository on GitHub
• You can fork your own repositories or other people’s repositories
• Different from cloning, forking will create a new repository on your GitHub account
• This is very useful, as you can push changes to your forked repository
• The fork maintains a connection to the original repository, often called the “upstream” repository
• Forks can be used to create entirely new projects based on the original codebase
• You can also create a pull request to the original repository to suggest changes

• After forking a repository, you may want to keep your forked repository up to date with the original repository
• This is pretty easy too
• Just go on GitHub and click on the “Sync fork” button and confirm the merge
  • Save your changes before doing this!
• This is surely the easiest way, but you can do it from the command line too
  • Add the original repository as a remote repository
    • git remote add upstream https://github.com/original-username/original-repository.git
    • git fetch upstream
    • git merge upstream/main (or upstream/master)
    • git push
    • Done! 🎉

• More about syncing a forked repository here.

• Issues are a way to track bugs, enhancements, or other tasks in a repository
• You can create an issue by clicking on the Issues tab on GitHub and then on the New issue button

• Gists are a great way to share code snippets, notes, or other text
• You can create a Gist by clicking on the + sign on the top right corner of GitHub and then on New gist
• Paste any text or code and save it
• You can also create secret Gists that are not indexed by search engines
• Gists also benefit from version control, so you can see the history of changes and revert to previous versions

• This is one of the nicest features of GitHub
• GitHub Pages allows you to create a website for your project, portfolio, or blog
• As you can see, I use GitHub Pages for this course and for my personal website
• You can create a website by creating a new repository with the name your-username.github.io
• Then, you can upload your .html, .css, and .js files to the repository
• Your website will be available at https://your-username.github.io
• You can also use custom domains and Jekyll themes, which are pre-designed templates
• Available themes here

• GitHub Actions is a way to automate your workflow
• Actions are workflows that run on GitHub when you push changes to your repository
• You can use them to build, test, package, release, and deploy your code
• They are a relatively new feature of GitHub and are very powerful
• Basically, you can create a .yml file with the steps you want to run
• Then, every time you push a new commit, GitHub will run the steps in the .yml file
  • For instance, you can update your website every time you change the text
  • Or you can test your code/run a model every time you push changes
  • I have one that automatically creates a list of my starred repositories every day

• GitHub CLI is a command-line tool that brings GitHub to your terminal
• You can install it with brew install gh
• GitHub CLI creates repositories, issues, pull requests, and more
• I use it both to create repositories and clone/fork them
  • gh repo create my-project
  • gh repo clone danilofreire/my-project
• Have a look at the GitHub CLI manual for more information

• Okay, I have the feeling that you are already tired of me talking about GitHub 😂
• But I’ve left the coolest feature for last: GitHub Copilot
• This is really cool! GitHub Copilot is an AI pair programmer that helps you write code
• Think about ChatGPT but for code
• It is based on OpenAI’s Codex and is available as a Visual Studio Code extension
• You can use it to write entire functions, classes, or even entire programs
• Like ChatGPT, it is not perfect, but it is really good and can save you a lot of time