Collaborating with GitHub

Overview

Teaching: 25 min
Exercises: 0 min

Questions

• What is a remote repository?

• How can I use GitHub to work from multiple locations?

Objectives

• Understand how to set up remote repository

• Understand how to push local changes to a remote repository

• Understand how to clone a remote repository

To collaborate with your colleagues as well as your self, we will need to set up a remote destination to save our work AND our history.

GitHub

GitHub is a company which provides remote repositories for Git and a range of functionalities supporting their use. GitHub allows users to set up their private and public source code Git repositories. It provides tools for browsing, collaborating on and documenting code. GitHub, like other services such as GitLab and Bitbucket, supports a wealth of resources to support projects including:

• Browsing code from within a web browser, with syntax highlighting
• Software release management
• Issue and bug tracking
• Project management tools

GitHub for research

GitHub isn’t the only remote repositories provider. It is very popular, however, particularly within the open source communities.

Also, GitHub has functionality which is particularly useful for researchers such as making code citable!

Get a GitHub account

Sign up or sign in if you already have an account.

Create a new repository

Now, we can create a repository on GitHub,

• Log in to GitHub
• Click on the New icon to create a new repository
• Enter Repository name: “git-papers”
• For the purpose of this exercise we’ll create a public repository
• Since we’ll be importing a local repository, make sure that Initialize this repository with a README is unselected
• Click Create Repository

You’ll get a page with new information about your repository. We already have our local repository and we will be pushing it to GitHub, so we can do the following:

$ git remote add origin https://github.com/<USERNAME>/git-papers.git

This line sets up an alias origin, to correspond to the URL of our new repository on GitHub.

As of a few months ago, the wider Git community renamed the default branch from master to main. Some of our Git versions might be outdated, so by default we are still creating master default branches when we do git init. We can fix this by by moving our current master branch into main with git branch -m master main. For a more thorough explanation of the situation and some guidelines, see https://github.com/github/renaming.

Push locally tracked files to a remote repository

Now we can execute the following:

$ git push -u origin main

Counting objects: 32, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (28/28), done.
Writing objects: 100% (32/32), 3.29 KiB | 0 bytes/s, done.
Total 32 (delta 7), reused 0 (delta 0)
To https://github.com/<USERNAME>/git-papers.git
 * [new branch]      main -> main
Branch main set up to track remote branch main from origin.

This pushes our main branch to the remote repository, (named via the alias origin) and creates a new main branch in the remote repository.

Now, on GitHub, we should see our code, and if we click the Commits tab we should see our complete history of commits.

Our local repository is now available on GitHub. This means that anywhere we can access GitHub, we can access our repository!

Push other local branches to a remote repository

Let’s push each of our local branches into our remote repository:

$ git push origin branch_name

The branch should now be created in our GitHub repository.

To list all branches (local and remote):

$ git branch -a

Deleting branches (for information only)

Don’t do this now. This is just for information. To delete branches, use the following syntax:

$ git branch -d <branch_name>			# For local branches
$ git push origin --delete <branch_name>	# For remote branches

Cloning a remote repository

Now, let’s do something drastic! But before that step, make sure that you pushed all your local branches into the remote repository!

$ cd ..
$ rm -rf git-papers

Gulp! We’ve just wiped our local repository! But, because we’ve pushed to GitHub, we have still have a copy! We can just copy the repository down using git clone:

$ git clone https://github.com/<USERNAME>/git-papers.git

Cloning into 'git-papers'...
remote: Counting objects: 32, done.
remote: Compressing objects: 100% (21/21), done.
remote: Total 32 (delta 7), reused 32 (delta 7), pack-reused 0
Unpacking objects: 100% (32/32), done.
Checking connectivity... done.

Cloning creates an exact copy of the repository. By default it creates a directory with the same name as the name of the repository.

Now, if we change into git-papers we can see that we have our repository,

$ cd git-papers
$ git log

and we can see our Git configuration files too:

$ ls -A

In order to see the other branches locally, we can check them out as before:

$ git branch -r					# Show remote branches
$ git checkout paperWJohn			# Check out the paperWJohn branch

Push changes to a remote repository

We can use our cloned repository just as if it were the original, local repository ! So, let’s make some changes to our files and commit these.

$ git checkout main				# We'll continue working on the main branch
$ vim journal.md				# Add results section
$ git add journal.md				# Stage changes
$ git commit

Having done that, how do we send our changes back to the remote repository? We can do this by pushing our changes:

$ git push origin main

If we now check our GitHub page we should be able to see our new changes under the Commit tab.

To see all configured remotes for this repository (we can have multiple!), type:

$ git remote -v

Key Points

• Git is the version control system: GitHub is a remote repositories provider.

• git clone to make a local copy of a remote repository

• git push to send local changes to remote repository