OverviewTeaching: 25 min
Exercises: 0 minQuestions
How can I use version control to collaborate with other people?Objectives
Clone a remote repository.
Collaborate pushing to a common repository.
Describe the basic collaborative workflow.
For the next step, get into pairs. One person will be the “Owner” and the other will be the “Collaborator”. The goal is that the Collaborator add changes into the Owner’s repository. We will switch roles at the end, so both persons will play Owner and Collaborator.
Practicing By Yourself
If you’re working through this lesson on your own, you can carry on by opening a second terminal window. This window will represent your partner, working on another computer. You won’t need to give anyone access on GitHub, because both ‘partners’ are you.
The Owner needs to give the Collaborator access. On GitHub, click the settings button on the right, then select Collaborators, and enter your partner’s username.
To accept access to the Owner’s repo, the Collaborator needs to go to https://github.com/notifications. Once there she can accept access to the Owner’s repo.
Next, the Collaborator needs to download a copy of the Owner’s repository to her
machine. This is called “cloning a repo”. To clone the Owner’s repo into
Desktop folder, the Collaborator enters:
$ git clone https://github.com/mhamilton/planets.git ~/Desktop/mhamilton-planets
Replace ‘mhamilton’ with the Owner’s username.
The Collaborator can now make a change in her clone of the Owner’s repository, exactly the same way as we’ve been doing before:
$ cd ~/Desktop/mhamilton-planets $ nano pluto.txt $ cat pluto.txt
It is so a planet!
$ git add pluto.txt $ git commit -m "Add notes about Pluto"
1 file changed, 1 insertion(+) create mode 100644 pluto.txt
Then push the change to the Owner’s repository on GitHub:
$ git push origin master
Counting objects: 4, done. Delta compression using up to 4 threads. Compressing objects: 100% (2/2), done. Writing objects: 100% (3/3), 306 bytes, done. Total 3 (delta 0), reused 0 (delta 0) To https://github.com/mhamilton/planets.git 9272da5..29aba7c master -> master
Note that we didn’t have to create a remote called
origin: Git uses this
name by default when we clone a repository. (This is why
origin was a
sensible choice earlier when we were setting up remotes by hand.)
Some more about remotes
In this episode and the previous one, our local repository has had a single “remote”, called
origin. A remote is a copy of the repository that is hosted somewhere else, that we can push to and pull from, and there’s no reason that you have to work with only one. For example, on some large projects you might have your own copy in your own GitHub account (you’d probably call this
origin) and also the main “upstream” project repository (let’s call this
upstreamfor the sake of examples). You would pull from
upstreamfrom time to time to get the latest updates that other people have committed.
Remember that the name you give to a remote only exists locally. It’s an alias that you choose - whether
fred- and not something intrinstic to the remote repository.
git remotefamily of commands is used to set up and alter the remotes associated with a repository. Here are some of the most useful ones:
git remote -vlists all the remotes that are configured (we already used this in the last episode)
git remote add [name] [url]is used to add a new remote
git remote remove [name]removes a remote. Note that it doesn’t affect the remote repository at all - it just removes the link to it from the local repo.
git remote set-url [name] [newurl]changes the URL that is associated with the remote. This is useful if it has moved, e.g. to a different GitHub account, or from GitHub to a different hosting service. Or, if we made a typo when adding it!
git remote rename [oldname] [newname]changes the local alias by which a remote is known - its name. For example, one could use this to change
Take a look to the Owner’s repository on its GitHub website now (maybe you need to refresh your browser.) You should be able to see the new commit made by the Collaborator.
To download the Collaborator’s changes from GitHub, the Owner now enters:
$ git pull origin master
remote: Counting objects: 4, done. remote: Compressing objects: 100% (2/2), done. remote: Total 3 (delta 0), reused 3 (delta 0) Unpacking objects: 100% (3/3), done. From https://github.com/mhamilton/planets * branch master -> FETCH_HEAD Updating 9272da5..29aba7c Fast-forward pluto.txt | 1 + 1 file changed, 1 insertion(+) create mode 100644 pluto.txt
Now the three repositories (Owner’s local, Collaborator’s local, and Owner’s on GitHub) are back in sync.
A Basic Collaborative Workflow
In practice, it is good to be sure that you have an updated version of the repository you are collaborating on, so you should
git pullbefore making our changes. The basic collaborative workflow would be:
- update your local repo with
git pull origin master,
- make your changes and stage them with
- commit your changes with
git commit -m, and
- upload the changes to GitHub with
git push origin master
It is better to make many commits with smaller changes rather than of one commit with massive changes: small commits are easier to read and review.
Switch Roles and Repeat
Switch roles and repeat the whole process.
The Owner pushed commits to the repository without giving any information to the Collaborator. How can the Collaborator find out what has changed with command line? And on GitHub?
On the command line, the Collaborator can use
git fetch origin masterto get the remote changes into the local repository, but without merging them. Then by running
git diff master origin/masterthe Collaborator will see the changes output in the terminal.
On GitHub, the Collaborator can go to their own fork of the repository and look right above the light blue latest commit bar for a gray bar saying “This branch is 1 commit behind Our-Repository:master.” On the far right of that gray bar is a Compare icon and link. On the Compare page the Collaborator should change the base fork to their own repository, then click the link in the paragraph above to “compare across forks”, and finally change the head fork to the main repository. This will show all the commits that are different.
Comment Changes in GitHub
The Collaborator has some questions about one line change made by the Owner and has some suggestions to propose.
With GitHub, it is possible to comment the diff of a commit. Over the line of code to comment, a blue comment icon appears to open a comment window.
The Collaborator posts its comments and suggestions using GitHub interface.
Version History, Backup, and Version Control
Some backup software can keep a history of the versions of your files. They also allows you to recover specific versions. How is this functionality different from version control? What are some of the benefits of using version control, Git and GitHub?
git clonecopies a remote repository to create a local repository with a remote called
originautomatically set up.