Understanding Git (part 1) — Explain it Like I’m Five

Kevin Cooper
· 9 min read
A confusing mess of branches. Photo by Brandon Green.

Understanding Git (part 1) — Explain it Like I’m Five
Understanding Git (part 2) — Contributing to a Team
Understanding Git (part 3) — Resolving Conflicts (stay tuned!)

Git is a powerful tool, but it has a reputation of baffling newcomers. It doesn’t help that most people are simply thrown in at the deep end and expected to swim.

With the right knowledge, anyone can master git. Once you start to understand it, the terminology will make more sense and you’ll (eventually) learn to love it. Stay strong 🙏

Why another guide?

There are plenty of “git tutorials” out there already, but most of them simply tell you to copy/paste specific things to do one-off tasks. Anyone with a keyboard can copy/paste; to really understand how git works and what it can do for you, you need a slightly deeper understanding.

They also tend to throw vocabulary at you without explaining what the words really mean.

This guide aims to give you a workable understanding of the basic phrases and commands you’ll use frequently. It’s impossible to learn such a powerful and complex tool in just one sitting, so I encourage you to take your time and enjoy the journey.

What is git?

First of all, GitHub is not git. Many people understandably confuse the two. GitHub is a website for hosting projects that use git.

Git is a type of version control system (VCS) that makes it easier to track changes to files. For example, when you edit a file, git can help you determine exactly what changed, who changed it, and why.

It’s useful for coordinating work among multiple people on a project, and for tracking progress over time by saving “checkpoints”. You could use it while writing an essay, or to track changes to artwork and design files.

Git isn’t the only version control system out there, but it’s by far the most popular. Many software developers use git daily, and understanding how to use it can give a major boost to your resume.

In complex projects, where multiple people might be making changes to the same files simultaneously, it’s easy to get into a weird state. Anyone who’s dealt with “merge conflicts” and those baffling >>>>>>> ======= <<<<<<< symbols can attest to this.

If you start to understand how git works, you’ll see why conflicts occur and how to recover from these situations easily.

How to get git

Git comes installed by default on many systems. If you don’t already have it:

  • You can download git’s command-line interface (CLI) here. I recommended this for both beginners and advanced users.
  • If you prefer to use a fancy graphical user interface (GUI) instead, try GitHub Desktop (for Windows and Mac). This will be simpler to use, but will make it more difficult to really see what’s going on.

The examples below all assume you’re using the CLI.

ℹ️ You use the command-line interface by typing in a terminal. If you’re not familiar with terminals, that’s okay — try this first (or search Google for help).

Common commands

Below is a series of basic commands with descriptions of what they each do. This section is intended to be interactive. As you read, feel free to try out the commands yourself before moving on. At the end there will also be a “real life” example with a list commands you can try all at once.

Notes:

  • Any jargon will be highlighted in bold the first time it’s described. Feel free to look up those terms in the official git glossary or reference guide for more details.
  • This is a simplified guide. It attempts to be as accurate as possible while avoiding some of the messier details. There are links at the end for more depth.
  • ✨ There will be some new insights in the descriptions, so make sure to keep reading.

Here are some of the most common commands, roughly in the order you will encounter them:

Start your own repository from scratch (in any existing folder on your computer):

git init

This will create a hidden .git folder inside your current folder — this is the "repository" (or repo) where git stores all of its internal tracking data. Any changes you make to any files within the original folder will now be possible to track.

✨ The original folder is now referred to as your working directory, as opposed to the repository (the .git folder) that tracks your changes. You work in the working directory. Simple!

Clone an existing repo:

git clone https://github.com/cooperka/emoji-commit-messages.git

This will download a .git repository from the internet (GitHub) to your computer and extract the latest snapshot of the repo (all the files) to your working directory. By default it will all be saved in a folder with the same name as the repo (in this case emoji-commit-messages).

✨ The URL you specify here is called the remote origin (the place where the files were originally downloaded from). This term will be used later on.

View the current status of your project:

git status

This will print some basic information, such as which files have recently been modified.

You should check your status anytime you’re confused. Git will print additional information depending on what’s currently going on in order to help you out.

Create a new branch name:

git branch <new-branch-name>

You can think of this like creating a local “checkpoint” (technically called a reference) and giving it a name. It’s similar to doing File > Save as… in a text editor; the new branch that gets created is a reference to the current state of your repo. The branch name can then be used in various other commands as you’ll soon see.

Similar to branching, more commonly you will save each checkpoint as you go along in the form of commits (see git commit below soon).

Commits are a particular type of checkpoint called a revision. The name will be a random-looking hash of numbers and letters such as e093542. This hash can then be used in various other commands just like branch names.

✨ That’s really the core function of git: To save checkpoints (revisions) and share them with other people. Everything revolves around this concept.

If you’ve ever created a checkpoint to something, you’ll be able to get back to it later as long as your .git folder is intact. It’s magical. See git reflog if you’re interested in learning more.

Branching is a huge and complex topic. I’ll write more about it soon; for now you can read more here if you want to.

Check out a particular branch:

git checkout <existing-branch-name>

You can think of this like “resuming” from an existing checkpoint. All your files will be reset to whatever state they were in on that particular branch.

⚠️ Keep in mind that any changes in your working directory will be kept around. See git stash if you’re interested in a simple way to avoid headaches.

😎 You can use the -b flag as a shortcut to create a new branch and then check it out all in one step. This is quite common:

git checkout -b <new-branch-name>

View the differences between checkpoints:

git diff <branch-name> <other-branch-name>

After editing some files, you can simply type git diff to view a list of the changes you’ve made. This is a good way to double-check your work before committing it.

For each group of changes, you’ll see what the file used to look like (prefixed with - and colored red), followed by what it looks like now (prefixed with + and colored green).

See further down for more advanced examples of this command.

Stage your changes to prepare for committing them:

git add <files>

After editing some files, this command will mark any changes you’ve made as “staged” (or “ready to be committed”).

⚠️ If you then go and make more changes, those new changes will not automatically be staged, even if you’ve changed the same files as before. This is useful for controlling exactly what you commit, but also a major source of confusion for newcomers.

If you’re ever unsure, just type git status again to see what’s going on. You’ll see “Changes to be committed:” followed by file names in green. Below that you’ll see “Changes not staged for commit:” followed by file names in red. These are not yet staged.

😎 As a shortcut, you can use wildcards just like with any other terminal command. For example:

git add README.md app/*.txt

This will add the file README.md, as well as every file in the app folder that ends in .txt. Typically you can just type git add --all to add everything that’s changed.

Commit your staged changes:

git commit

This will open your default command-line text editor and ask you to type in a commit message. As soon as you save and quit, your commit will be saved locally.

The commit message is important to help other people understand what was changed and why you changed it. There’s a brief guide here explaining how to write useful commit messages.

😎 You can use the -m flag as a shortcut to write a message. For example:

git commit -m “Add a new feature”

Push your branch to upload it somewhere else:

git push origin <branch-name>

This will upload your branch to the remote named origin (remember, that’s the URL defined initially during clone).

After a successful push, your teammates will then be able to pull your branch to view your commits (see git pull below).

😎 As a shortcut, you can type the word HEAD instead of branch-name to automatically use the branch you’re currently on. HEAD always refers to your latest checkpoint, that is, the latest commit on your current branch.

✨ As mentioned earlier, everything in git can be thought of as a checkpoint. Here’s a list of the types of checkpoint you know about now (again, these are technically called “references” and “revisions”):

  • HEAD
  • <branch-name>, e.g. master
  • <commit-hash>, e.g. e093542d01d11c917c316bfaffd6c4e5633aba58 (or e093542 for short)

There’s also:

  • <tag-name>, e.g. v1.0.0
  • stash

Finally, special characters like ^, ~, and @{} can be used to modify references. They're quite useful; learn more here.

Fetch the latest info about a repo:

git fetch

This will download the latest info about the repo from origin (such as all the different branches stored on GitHub).

It doesn’t change any of your local files — just updates the tracking data stored in the .git folder.

Merge in changes from somebody else:

git merge <other-branch-name>

This will take all commits that exist on the other-branch-name branch and integrate them into your own current branch.

⚠️ This uses whatever branch data is stored locally, so make sure you’ve run git fetch first to download the latest info.

For example, if someone else adds a few commits to the master branch of origin, you can do the following to download their changes and update your own local master branch:

git checkout master      # Make sure you're on the right branch.
git fetch # Download any new info from origin.
git merge origin/master # Merge the 'origin/master' branch
into your current branch.

✨ The name origin/master here literally means the origin/master checkpoint on your computer. Git uses this notation to differentiate branches of the same name (e.g. master) located in different places (e.g. your own branches vs. origin's branches).

😎 As a shortcut, you can use the pull command to both fetch and merge all in one step. This is more common than merging manually like above:

git pull origin master

Here we separate the words origin and master (without a slash like above). We don't want to use the origin/master checkpoint on our own computer, because that's stored offline and is probably out of date. We instead want to fetch directly from the master branch of the remote endpoint called origin. Keep an eye out; the difference is important!

For a deeper understanding of how merging works and how conflicts are resolved (with fun pictures and graphs), see the official merge docs. This will also be covered extensively in part 3 of this series.

Real life example

Here’s a series of commands that could hypothetically be executed while developing a real feature. See if you can figure out what they would each do, then try it out yourself and check.

git clone https://github.com/cooperka/emoji-commit-messages.git
cd emoji-commit-messages
git status
git checkout -b my-new-feature
echo “This is a cool new file” > my-file.txt
git status
git add --all
git status
git diff HEAD
git commit -m “Add my-file.txt”
git status
git log
git push origin HEAD
git checkout master
git pull

Most of these commands have additional parameters you can pass to customize them, and shorthand versions for brevity, all of which make everything more interesting (read: confusing). There’s usually more than one way to accomplish a given task.

Now what?

Now you know everything there is to know about git!

…just kidding, this is only the tip of the iceberg. There’s a lot more you need to understand before you can claim to be an expert, but for now, you at least have the basics to be able to work with a team and understand the lingo.

Once you understand these basic commands, you can and should continue to learn more from git’s website or this more advanced guide.

If you found this useful, please help by tapping the 👏 button as many times as you’d like so others can find it too.

Thank you, and stay tuned for part 2. Let me know in the comments if there are any specific topics you’re interested in.

HackerNoon.com

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Kevin Cooper

Written by

Freelance software developer. Interested in social justice and ethical technology.

HackerNoon.com

how hackers start their afternoons.

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