Git Hello World
Open Source
You might have heard of Open Source before, as there has been an infinite amount written about the subject, but this is a good time to learn about it. In fact, this course is entirely open source!
Open source and hacking go hand in hand. You might not feel strongly about it now, but you probably will eventually.
What is Open Source? https://opensource.com/resources/what-open-source
Git
Before we get to Github we have to learn about the software it is built around, which is named 'git'. Git was developed by…. drumroll… Linus Torvalds! Basically, once he started working on Linux with a bunch of other programmers, he needed a dedicated type of software so everyone could work on different pieces without stepping on each other's toes. What was created is something now known as a “version control system” or VCS.
There are a variety out there, but Git is clearly dominant. Git is used for version control during software development, allowing collaboration and the merging of changes in a safe and easy manner. It is used by just about everyone and is amazing. If you want to build large pieces of software, especially as a group, you need to use version control. However, as you’re about to find out, git can be a bit of a beast to manage.
Github
Luckily, some helpful folks decided to add features to git that old Linus would have never agreed to, and now we have Github. Github is a website that wraps git and allows you to share your code via their website, as well as letting you download other people's code. It’s The Place for sharing the source code of your digital creations with the world, and checking out what others have written.
Repositories
The way git works is by manipulating things named “repositories” or “repos”. By keeping track of all the code, and all the changes to the code over time, git is able to show snapshots of what the code looks like at different points. Inside of each repo there can be multiple “branches” which git will also keep track of. This means that different programmers can be working on different branches inside of one repo, and then “commit” their changes to the main branch. The git software will keep verify nothing conflicts, keep track of who did what when, and then “merge” all the code together. We can host our git repos locally or somewhere in the cloud. The primary objective of Github is to be that remote location to store git repos. Github and git knowledge is basically required for any programmer job, so let’s do a quick lab to drive home how that works.
Tutorial
First, make a github account at https://github.com
Then ensure git is installed on your computer with "git status". If it is not, install git.
Once you have verified that you have git on your computer and made a Github account, it is time to 'fork' my repository https://github.com/hoppersroppers/demoHtml. Forking is the cool programmer word for making a personal copy of a repo.
There are multiple ways you can do this, but the way we will do it here, will combine the Github Web Interface and some CLI action. First, "fork" https://github.com/hoppersroppers/demoHtml via the Github website by clicking the fork button in the top right. Now you can refer to your repo as a fork of mine, which honestly sounds cool, plus it makes sense!
Now, let's clone your fork to your computer.
$ git clone https://github.com/---yourUserName---/demoHtml
This will make a local copy of your fork on your computer. Keep in mind,
this is not considered forking your fork, simply cloning. Check that the
repo downloaded with ls and then cd into it.
Files in the Git Repo
Use ls to see what is in the directory. You should see hello.html,
README.md, and a LICENSE.
README.md is the common name of the file used to understand what is going on in the repo. If you visit your repo you forked you will see that the README is displayed to you when you click in.
LICENSE is the common filename of the Open Source license the file is released under. There is a ton of complexity in this that is basically copyright law, so for now don’t worry about it, but just know that it is important to check these out before blindly taking someone else’s code and using it in your work. You can click to your Repo in Github to see what the License is in the top line.
Finally we have hello.html. It’s a regular HTML file which is the language websites are built with. We can render it in our browser by opening it and selecting our browser as the correct program. We can also edit it by selecting a text editor to open it, liked gedit or one of our command line options. If you've ever looked at "View Source" in your browser before, you were looking at HTML.
Editing Our First File
First, run git status to check out how everything is going. If you get
errors, figure them out before moving forward... as I like to say, the
best time to fix merge issues is before you find out about them.
status will tell you right now that you are in branch "main". "main" is the default branch name for a Github repo. It is possible to switch branches and have different changes in each branch, but for now, everything we will do is in main.
Git has man pages, but basically instead of flags, we have a family of commands we run as the second argument. When you’re having issues with git, basically the right move is to check out google and find a useful resource for the problem you are having. Search the error code and someone out there will have fixed it before, I promise.
After we check status, edit your hello.html file and change what the
text says in the header and body. Verify in your browser that the change
worked! Now run git status again! What changed?
You will be seeing that you have one “untracked” file now, basically meaning that git knows you made changes but isn’t going to do anything with them. So first, you have to get that file to be “tracked”.
$ git add hello.html
To be even faster, you could have run $git add *. Now check git status
again.
Verify your changes have been tracked and let’s commit them!
$ git commit -m "modified hello"
That commit -m puts your tracked changes into the local repo, and writes a message to the log with whatever you specified. If this fails, and it will if you've never set up git on your local computer before, run the commands in the error message to set your name and email. Once that has been done, run the commit again and it should work!
Check git status to ensure your commit worked. You should see now that
you are one commit ahead of the remote repo.
If you check that remote repo on Github you will see that nothing has happened there yet. To get something to happen on Remote, you need to “push”.
Before pushing, we need to know the name of remote. Most of the time we
can guess it will be origin, but if you are doing fancier things really
anything could be there. To check the name, run git remote.
After verifying the name is origin, run git push origin main.
You will get an error message here! Github has decided to no longer allow password-based authentication for pushing to repositories. You can read more about this here: https://github.blog/2020-12-15-token-authentication-requirements-for-git-operations/#what-you-need-to-do-today
Using Google and links provided to you, generate a personal access token and use that to authenticate the next time you push. Make sure to save that access token somewhere safe, and don't commit it to any of your git repos!!!!
Once git push origin mainhas succeeded, check your github repo and
verify the changes have been made. Congratulations on your first ever
push!
Pull!
Now, let’s get a pull in! Pulling is the act of taking code from somewhere else and bringing it into a repository. First, let’s make a change in your Github repository! From the website, update the name in your README.md to say your name by clicking on the edit button in the GUI and committing your changes. You can probably guess by now that your local copy of the repo will not have that change yet, but you can verify if you want.
So now, your local repo is one commit behind the remote one… time to fix that!
$ git pull origin main
Git pull combines two commands “fetch” and “merge”, which fetch the remote repo and merge the two repos together. For more complicated things, you might have to or want to fetch and merge separately, but life is easier with a one command pull on a simple repo like this.
Verify the change has been made locally and congrats! You now have more git knowledge than the average computer science graduate. Practical skills rock!
All things considered, git and Github are incredibly complicated and this simple little demo might have oversimplified things, but honestly... this is good enough to start! You'll be using plenty more git throughout the rest of the course and believe me, you will find plenty of ways to break it, and then fix it back up again. (And worst comes to worst, you can always just make a new repo!)
Assignment:
- Explain what open source is in a few sentences and what the benefits are.
- Submit a link to your first repo