| ⬅ 5. Working with branches | Table of Contents | 7. Collaborating ➡ |
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Version control really comes into its own when we begin to collaborate with other people. We already have most of the machinery we need to do this; the only thing missing is to copy changes from one repository to another.
Systems like Git allow us to move work between any two repositories. In practice, though, it's easiest to use one copy as a central hub, and to keep it on the web rather than on someone's laptop. In fact, by using a central hub you can easily store your work done on one machine (say, at home) and load it onto another machine (say, in a computer lab) in exactly the state you left it. Most programmers use hosting services like GitHub, BitBucket or GitLab to hold those master copies; we will use GitHub.
Let's start by sharing the changes we've made to our current project with the
world. Log in to GitHub, then click on the icon in the top right corner to
create a new repository called planets:
Name your repository "planets" and then click "Create Repository". DON'T check the "Initialize this..." box:
As soon as the repository is created, GitHub displays a page with a URL and some information on how to configure your local repository (you can ignore this for now):
The last step effectively did the following on GitHub's servers:
$ mkdir planets
$ cd planets
$ git init
Our local repository still contains our earlier work on mars.txt, but the
remote repository on GitHub doesn't contain any files yet:
The next step is to connect the two repositories. We do this by making the GitHub repository a remote for the local repository. The home page of the repository on GitHub includes the string we need to identify it:
Click on the 'HTTPS' link to change the protocol from SSH to HTTPS.
Copy that URL from the browser, go into the local planets repository, and run
this command:
$ git remote add origin https://github.com/vlad/planets.git
Make sure to use the URL for your repository rather than Vlad's: the only
difference should be your username instead of vlad.
We can check that the command has worked by running git remote -v:
$ git remote -v
origin https://github.com/vlad/planets.git (push)
origin https://github.com/vlad/planets.git (fetch)
The name origin is a local nickname for your remote repository: we could use
something else if we wanted to, but origin is by far the most common choice.
Once the nickname origin is set up, git push origin master will push the changes from
our local repository to the repository on GitHub (but don't type it yet)
You can now push to the respository on github. Note we omit the -u in the github instructions because using -u assumes you won't change the branches you are pushing/pulling. In fact you will want to use branches to get the full power of git. If you have a MAC then you may get an authentification failed error. Windows users should have this already taken care of during the install git instructions for windows where the credential manager core is also included. Follow the steps here if you get an error trying to do the next step: https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/creating-a-personal-access-token
$ git push origin master
Counting objects: 9, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (6/6), done.
Writing objects: 100% (9/9), 821 bytes, done.
Total 9 (delta 2), reused 0 (delta 0)
To https://github.com/vlad/planets
* [new branch] master -> master
Branch master set up to track remote branch master from origin.
Our local and remote repositories are now in this state:
We can pull changes from the remote repository to the local one as well:
$ git pull origin master
From https://github.com/vlad/planets
* branch master -FETCH_HEAD
Already up-to-date.
Pulling has no effect in this case because the two repositories are already synchronized. If someone else had pushed some changes to the repository on GitHub, though, this command would download them to our local repository.
Browse to your planets repository on GitHub.
Under the Code tab, find and click on the text that says "XX commits" (where "XX" is some number).
Hover over, and click on, the three buttons to the right of each commit.
What information can you gather/explore from these buttons?
How would you get that same information in the shell?
Make changes to your local planets/ repository (add a file called mercury.txt or so) and push these changes. Go to the repo you just created on Github and check the timestamps of the files. How does GitHub record times, and why?
In this lesson, we introduced the "git push" command. How is "git push" different from "git commit"?
In this section we learned about creating a remote repository on GitHub, but when you initialized your GitHub repo, you didn't add a README.md or a license file. If you had, what do you think would have happened when you tried to link your local and remote repositories?