How to Set Up .git 관련

A Visual Guide to Git Internals — Objects, Branches, and How to Create a Repo From Scratch

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Many of us use git on a daily basis. But how many of us know what goes on under the hood? For example, what happens when we use git commit? What is stored between commits? Is it just a diff between the current and previous commit? If so, how

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A Visual Guide to Git Internals — Objects, Branches, and How to Create a Repo From Scratch

Many of us use git on a daily basis. But how many of us know what goes on under the hood? For example, what happens when we use git commit? What is stored between commits? Is it just a diff between the current and previous commit? If so, how

Let’s create a new directory, and run git status within it:

Alright, so git seems unhappy as we don’t have a .git folder. The natural thing to do would be to simply create that directory:

Apparently, creating a .git directory is just not enough. We need to add some content to that directory.

A git repository has two main components:

1. A collection of objects — blobs, trees, and commits.
2. A system of naming those objects — called references.

A repository may also contain other things, such as git hooks, but at the very least — it must include objects and references.

Let’s create a directory for the objects at .git\objects and a directory for the references (in short: refs) at .git\refs (on UNIX -based systems — .git/objects and .git/refs, respectively).

One type of reference is branches. Internally, git calls branches by the name heads. So we will create a directory for them — .git\refs\heads.

This still doesn’t change our git status

How does git know where to start when looking for a commit in the repository? As I explained earlier, it looks for HEAD, which points to the current active branch (or commit, in some cases).

So, we need to create the HEAD, which is just a file residing at .git\HEAD. We can apply the following:

ECHO ref: refs/heads/master > .git\HEAD`

echo "ref: refs/heads/master" > .git/HEAD

⭐ So we now know how HEAD is implemented — it’s simply a file, and its contents describe what it points to.

Following the command above, git status seems to change its mind:

Notice that git believes we are on a branch called master, even though we haven’t created this branch. As mentioned before, master is just a name. We could also make git believe we are on a branch called banana if we wanted to:

🍌

We will switch back to master for the rest of this post, just to adhere to the normal convention.

Now that we have our .git directory ready, can we work our way to make a commit (again, without using git add or git commit).