Working with Git and GitHub

Collin Paschall

Working with Git and GitHub

• What? Git/GH are tools for file versioning.
• Why? Git/GH are very popular with tech folks.

Recognition

• This presentation draws very heavily on Karl Broman’s Git tutorial - kbroman.org/github_tutorial.

How Does Git work?

• Loosely, Git adds some “hidden files” in a directory/folder on your computer.
• These files help track changes to files in the folder.
• This folder is called a “repository.”

Git vs. GitHub

• Git is command line software. GitHub is an online web service for maintaining copies of repos. GitHub Desktop is a GUI wrapper for using Git on your computer.
• If you know Git, GitHub Desktop is a piece of cake. Nerd out, learn the command line.

Git Commands

• There are lots of ways to use Git commands. We are only doing the basics.
• git init: create a repository using an existing folder.
• git add: tell git you are done working with a file and the file is ready to “commit” to your repository. This is staging the file.
  • counterintuitively, this is also how you tell git that you want to remove a file you delete.
• git commit: make the modifications to the repository and keep track of them.
• git push: put your new files on GitHub

What we are going to do

• Set up Git on your computer
• Create a repository and connect it to GitHub
• Fork and suggest changes to a repository

Prereq - Linux/Bash command line

• Navigate using cd, cd .., and ls

Get started

• We can move faster if you set up SSH (secure shell) login for Git.
• Open your Terminal or Git Bash
• ssh-keygen -t rsa -C “[the mail address you use for GitHub]”
  • No need for passphrase, just “yes” at next
• Go to your user folder. Cmd+shift+. for Mac or “View Hidden Files” on Windows.
• Go to the ssh folder.
• Open the .pub file in a text editor. Copy that key.
• Go and add that to GitHub account settings (follow along).

Name and Email to Git

• git config --global user.name “[Your name]”
• git config --global user.email “[your email]”

Make a repository

• On the command line, navigate to a folder.
• Make a new folder in that directory (mkdir).
• Go into that directory (cd).
• Create a Hello World R file in that directory (cat > hello.r, print(“Hello World”), Ctrl-d)
• Initialize Git for that directory (git init)
• Check the status (git status)
• Add file we created (git add)
• Commit the change (git commit -m “First Commit”)

Push our repo to GitHub

• Click the new repository button in the top-right of your GH account.
• Create the repository
• Back in your terminal, set your remote connection
  • git remote add origin git@github.com:username/[the name of your repo]
• Rename your “master” branch”
  • git branch -M main
• Push your commit to the main branch
  • git push -u origin main

Collaborate Pt 1

• Fork github.com/collinpaschall.
• Open terminal/bash and navigate to the folder in which you want the local copy for the project
• Clone (download) a local copy: git clone git@github.com:[your username]/[the repo name]
• Go into that local folder (cd)
• Add a connection to the original repository -git remote add collinpaschall https://github.com/collinpaschall/teaching_repo
• Check that the remote is set up: git remote -v

Collaborate Pt 2

• Make some changes to this file using R Studio. Add a line with print(“[your name]”). Save.
• git add the file
• git commit -m “[your name] added”
• git push

Collaborate Pt 3

• Go to your own version of the forked repository.
• Click “pull request”.
• The owner of the original repo is notified.
• The owner will merge in your changes if s/he likes them.