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Lab 6: Git and GitHub Basics

Gaston Sanchez

Learning Objectives

  • Create a GitHub repository
  • Create a local Git repository
  • Practice adding, and committing changes to your (local) Git repo
  • Practice pushing committed changes to a remote repo

General Instructions

  • This lab involves 2 parts:
    1. GitHub workshop
    2. Git and GitHub Practice
  • We assume that you have installed Git in your computer, and that you created a GitHub account.
  • Write your descriptions, explanations, and code for the first two parts in an Rmd (R markdown) file.
  • Name this file as lab06-first-last.Rmd, where first and last are your first and last names (e.g. lab06-gaston-sanchez.Rmd).
  • Knit your Rmd file as an html document (default option).
  • Submit your Rmd and html files to bCourses, in the corresponding lab assignment.

Part 1) Git Workshop

The first part of the lab involves working on the workshop Version Control with Git by Software Carpentry, especifically parts 3 to 7 (I’m assuming that you have Git installed in your machine).

Introduce Yourself to Git

The first step involves introducing yourself to Git by running a couple of configuration commands. Basically, you need to tell Git who you are, and what your email is. Run the following commands using your own user name and you own email.

# use your own user name
git config --global user.name "Gaston Sanchez"

# use your own email
git config --global user.email "[email protected]"

# colors
git config --global color.ui "auto"

Your turn*

Write your bash commands inside one or more code chunks that are NOT evaluated. One way to do this is to add the option eval = FALSE inside the curly braces of the chunk (see image below)

  1. Setting Up Git
  2. Creating a Repository
  3. Tracking Changes
  4. Exploring History
  5. Ignoring Things
  6. Remotes in GitHub

Part 2) Git and GitHub Practice

The second part of the lab involves working on a baby project with Git. Here are some resources that you may find useful:

  • Chapters 1 Getting Started, and sections 2.1 to 2.5 in chapter 2 Git Basics, of the Pro Git by Scott Chacon and Ben Straub.

  • Github Git Cheat Sheet

Your Turn*: 1) Create a New GitHub Repository

  • Open your browser and Sign in to your github account.
  • Locate the + button (next to your avatar).
  • Select the New repository option.
  • Choose a name for your repository: e.g. demo-repo.
  • In the Description field add a brief description: e.g. “this is a demo repo”
  • Use the default settings, and click the green button Create repository.
  • You should see some content similar (but not identical) to the one below:
echo "# Demo Repo" >> README.md
git init
git add README.md
git commit -m "first commit"
git remote add origin https://github.com/gastonstat/demo-repo.git
git push -u origin master

Your Turn*: 2) Create a local Git Repository

  • Open the terminal (Mac Terminal, or Git-Bash for Windows users).
  • Optional: change directory to your preferred location e.g. your Desktop
cd Desktop
  • Create a directory with the name of your github repo
mkdir demo-repo
  • Change to the directory you just created
cd demo-repo
  • Initialize the directory as a git repository
git init

The command git init will set-up your directory demo-repo as a Git repository (NOT to confuse with your GitHub repository). This is basically your local repository.

NOTE: It’s possible that you encounter some error message, e.g. Mac users may get a message related with a missing component for CommandLineTools. If this is your case, then type in the terminal console:

# Mac users may need to run this command
xcode-select --install

Your Turn*: 3) Adding a README file

  • It is customary to add a README.md file at the top level. This file must contain (at least) a description of what the repository is about. The following command will create a README.md file with some minimalist content:
echo "# Demo Repo" >> README.md
  • So far you have a “new” file in your local repo, but this change has not been recorded by Git. You can confirm this by checking the status of the repo:
git status
  • Notice that Git knows that README.md is untracked. So let’s add the changes to Git’s database:
git add README.md
  • Check the status of the repo again:
git status
  • Now Git is tracking the file README.md.
  • Next thing consists of committing the changes. It’s always a good practice to include a meaningful message for your commit.
git commit -m "first commit"

Your Turn*: 4) Adding a remote

Right now you have a (local) Git repository in your computer. And you also have a (remote) GitHub repository in your GitHub account. Both repositories should have the same name, and the goal is to link them. To do this, you need to tell Git that a remote repository (i.e. the one in GitHub) will be added:

  • To add a remote repository use the command below with your own username:
git remote add origin https://github.com/username/demo-repo.git
  • Verify your new remote
git remote -v
  • If everything is okay, you should be able to see a message (with your own username) like this:
# Verify new remote
origin  https://github.com/username/demo-repo.git (fetch)
origin  https://github.com/username/demo-repo.git (push)

Your Turn*: 5) Pushing changes to a remote repo

  • Now that you have linked your local repo with your remote repo, you can start pushing (i.e. uploading) commits to GitHub.
  • As part of the basic workflow with git and github, you want to constantly check the status of your repo
git status
  • Now let’s push your recent commit to the remote branch (origin) from the local branch (master):
git push origin master
  • Go to your Github repository and refresh the browser. If everything went fine, you should be able to see the contents of your customized README.md file.
  • Keep modifying the content of README.md file, add the modifications to the git repository, display the status, commit the modifications, and push them to github repo.