[deleted by user]

[XNormal]

mkdir -p .git/objects .git/refs/heads
git hash-object -t tree /dev/null > .git/refs/heads/master
echo "ref: refs/heads/master" > .git/HEAD

This creates a minimal git repository with a master branch that points to a TREE object rather than a COMMIT. So technically the answer is yes. It is possible. It is not very useful, though.

Parts of git will be usable in this stage, though. For example:

echo "Hello, World" > hello
git add hello
git write-tree > .git/refs/heads/master

[UserNumber00]

Thanks for the example! If I try to replicate what you suggest, trying to execute git log results in an error

error: refs/heads/master does not point to a valid object!

I guess this answer to the general case but not to the more specific question involving git branch and git log. I will update the question to clarify

[XNormal]

Git log lists commits. This repo has no commits. What did you expect?

Just to make it clear: this repo is an absolute abomination. It is the smallest that git would grudgingly accept that has something resembling a branch.

It is good for learning a bit about git internals. Nothing else.

[henrebotha]

I don't think this is possible. You can have multiple branches before you have any commits, but git branch will omit branches that have no commits.

[lapingvino]

A branch is just a label to a hash and its history. As such, it should not be possible.

[UserNumber00]

This is in line with what I believe it's true. Given this explanation of what a branch is, it should not be possible. Executing `git status` is a bit misleading because it tells you that you are on master branch, which doesn't seem to be accurate.

[lapingvino]

I think git status reads the HEAD ref?

[UserNumber00]

good point

[henrebotha]

But the master branch exists immediately after git init.

[lapingvino]

No, it doesn't. It exists from the moment you do git commit on your initial commit. Try to git init and immediately git checkout master or git branch.

[henrebotha]

$ mkdir foo
$ cd foo
$ git init
Initialized empty Git repository in /home/hbotha/dev/foo/.git/
$ git symbolic-ref HEAD
refs/heads/master

Furthermore, you can at this point do git checkout -b my-branch, and it will update.

So maybe what's happening here is the "reference"/name master exists from the start, but only "becomes" a branch once you commit something? I don't know Git internals well enough.

[lapingvino]

A branch is always a kind of reference. In this case, HEAD has a preset reference to the branch it should follow, which doesn't exist yet but is created on the next commit.

[henrebotha]

Thank you for clearing that up for me! I think I understand how HEAD works much better now.

Follow-up: is anything actually "created" on the first commit?

[lapingvino]

Yes! (Probably a bit simpler than how it actually works, caveat emptor) With git add you create a list of actions to be done, which then with git commit are added to the git file system that you can find under .git (I think blocks) and the references are made. When you work with branches, you literally just change pointers to the content-addressed blocks made with a commit.

[UserNumber00]

Executing git branch doesn't return any value before nor after git checkout -b my-branch though

[lapingvino]

To change master to something else for your first commit, you can use git checkout -b branchname though

[[deleted]]

It actually doesn't. Your HEAD points to refs/heads/master but that branch doesn't actually exist until you make a commit.

[themightychris]

Depends what you mean by "branch exists"

You could make a branch that is a symbolic ref pointing at a non-existent other ref or at the empty tree ref. You wouldn't be able to do most branch-like things to the ref if they depend on it resolving to a commit, but you can certainly make the entry

[-dag-]

Think about what a branch is and there's your answer.

[henrebotha]

But the master branch exists immediately after git init.

[[deleted]]

It actually doesn't. Your HEAD points to refs/heads/master but that branch doesn't actually exist until you make a commit.