1-2: Git Repositories

We've used the term "repo" or "repository" a number of times already. But what is a Git repo?

Simply, it's a folder with a hidden .git folder inside of it that manages versions and changes of the contents.

More nerdily, it's a folder turned into a TARDIS: it contains more than it looks like, and it can travel in time and between possible realities.

Creating Git Repos

Let's start from the assumption that you have Git installed. On the command line, run git --version to make sure.

While we're at it, let's configure Git for our usage. We need to tell Git who we are, so our changes (commits) can be labeled. We do so by providing a username and an email address.

git config --global user.name=username
git config --global user.email=user@domain.com

The username and email don't have to match your GitHub account, but it's not a bad idea.

With that out of the way, let's make a new folder outside of this repository. We'll use this folder as a sort of laboratory for Git experiments. Then we can take what we've learned and apply it to the Checks for Understanding in this repo.

mkdir gitdemo
cd gitdemo
git init -b main

Note: The -b main isn't strictly necessary, but we do it to make the name of our default branch "main" instead of the built-in "master." Lots of folks are uncomfortable with that language, and it's easy to fix.

git init initializes a Git repo in the current folders. It won't seem like much occurred after you run this command, but just under the surface, quite a bit has taken place. Run ls -al and you'll see a hidden .git folder. Listing those contents will result in something like this:

total 40
drwxrwxr-x 7 user user 4096 Feb 26 15:03 .
drwxrwxr-x 3 user user 4096 Feb 26 15:03 ..
drwxrwxr-x 2 user user 4096 Feb 26 15:03 branches
-rw-rw-r-- 1 user user   92 Feb 26 15:03 config
-rw-rw-r-- 1 user user   73 Feb 26 15:03 description
-rw-rw-r-- 1 user user   21 Feb 26 15:03 HEAD
drwxrwxr-x 2 user user 4096 Feb 26 15:03 hooks
drwxrwxr-x 2 user user 4096 Feb 26 15:03 info
drwxrwxr-x 4 user user 4096 Feb 26 15:03 objects
drwxrwxr-x 4 user user 4096 Feb 26 15:03 refs

You're looking at what makes a Git repo a Git repo. You do not have to understand what each file and directory in .git does, but it helps to understand that this folder contains the Git magic. In fact, if you deleted all the files in a repo except for the .git folder, you'd still be able to reconstruct the files from the last commit!

Before we move on to make our first commit, let's quickly look at the contents of the .git/config file.

[core]
    repositoryformatversion = 0
    filemode = true
    bare = false
    logallrefupdates = true

Now for comparison, check this repo's .git/config file. You may be able to see why this file is so important.

Let's move on to the basic workflow in Git, or the "core loop."