Session 4 · Initialize a repository#

The big idea#

git init turns any folder into a Git repository by creating a hidden .git folder inside it. From then on Git can watch that folder. Nothing is saved yet: a new repository is empty until you make your first commit.

Everyday example: opening a new notebook. The notebook exists and has a cover (the .git folder), but there is nothing written in it. git status is you flipping through it to see what is inside and what is not recorded yet.

Working folder, staging area, repository You edit files in the working folder, choose what goes into the next snapshot with git add, and git commit stores it in the repository. Working folder files you edit Staging area the next snapshot, being prepared Repository saved history (.git) git add git commit git restore --staged git status shows the difference between each pair of areas
You edit files in the working folder, choose what goes into the next snapshot with git add, and git commit stores it in the repository.

Create MyProject#

mkdir MyProject
cd MyProject
git init

echo '--- is it a repository now?'
git status

echo '--- what did init create?'
ls -A
ls .git

echo '--- the default branch name is a setting'
git config --global init.defaultBranch main
git init -q ../Another
git -C ../Another branch --show-current

echo '--- running git in a folder that is not a repository'
cd /
git status 2>&1 | head -1

hint: Using 'master' as the name for the initial branch. This default branch name
hint: is subject to change. To configure the initial branch name to use in all
hint: of your new repositories, which will suppress this warning, call:
hint: 
hint: 	git config --global init.defaultBranch <name>
hint: 
hint: Names commonly chosen instead of 'master' are 'main', 'trunk' and
hint: 'development'. The just-created branch can be renamed via this command:
hint: 
hint: 	git branch -m <name>
Initialized empty Git repository in ~/work/MyProject/.git/
--- is it a repository now?
On branch master

No commits yet

nothing to commit (create/copy files and use "git add" to track)
--- what did init create?
.git
branches
config
description
HEAD
hooks
info
objects
refs
--- the default branch name is a setting
main
--- running git in a folder that is not a repository
fatal: not a git repository (or any of the parent directories): .git

What happened:

  • The long hint: block appears when you have not chosen a default branch name. Git used master, as you can see in On branch master. The hint tells you how to change it. Run git config --global init.defaultBranch main once and every new repository starts on main.

  • Initialized empty Git repository confirms .git was created.

  • git status says No commits yet and nothing to commit. The repository is valid, just empty.

  • ls -A shows that the only thing init added is .git. Inside it live HEAD (which branch you are on), config (this repository’s settings), objects (the stored snapshots) and refs (branch names).

  • After the setting, the second repository’s branch is main.

  • Outside a repository, git status fails with fatal: not a git repository. That message simply means you are in the wrong folder.

What lives inside .git#

You rarely need to open .git, but knowing what is in it removes the mystery. objects holds every snapshot you will ever commit, stored compactly and addressed by hash. refs holds the names (branches and tags) that point at those snapshots. HEAD is a one-line file saying which branch you are on. config is the local settings file from Session 2. Because all of this sits in one folder, you can copy a project with its whole history just by copying the folder, and you can delete the history by deleting .git.

The files next to .git (your actual project files) are called the working folder. Git compares the working folder with what is stored in .git every time you run git status.

Where to run git init#

Run it once, in the top folder of the project, not in every subfolder and never in your whole home directory. A repository inside another repository confuses Git, and an accidental git init in ~ makes git status list everything you own.

Common mistakes#

  • git init inside an existing repository (or a subfolder of one). You create a nested repository. Check with git status first.

  • Running git init in the wrong folder, such as your home or Downloads folder. Delete the stray .git folder.

  • Forgetting the first commit. Until you commit, git log fails with “does not have any commits yet”.

  • Confusing git init with git clone. Init starts a new empty history; clone copies an existing one.

  • Ignoring the branch-name hint. master and main mixed across projects confuses scripts. Pick one default.

Hands-on exercises#

Exercise 1. Create MyProject, initialise it and confirm with git status.

Solution 
mkdir MyProject
cd MyProject
git init
git status

Expected: Initialized empty Git repository ... then On branch main (or master), No commits yet.

Exercise 2. Make a second repository Other and a project-specific identity ProjectUser just for it. Prove that MyProject is unaffected.

Solution 
git init Other && cd Other
git config user.name "ProjectUser"
git config user.email "projectuser@example.com"
cd ../MyProject
git config user.name        # prints your global name, not ProjectUser

Local settings live in each repository’s own .git/config.

Exercise 3. Find out which branch a new repository starts on and change the default for all future ones.

Solution 
git init try1 && git -C try1 branch --show-current
git config --global init.defaultBranch main
git init try2 && git -C try2 branch --show-current

Before the setting an older Git prints master (as in the output above); after it, main.

Practice#

Take the Session 4 quiz. The original Q1 Initialize a Repository and Basic Configurations page is in the reference section.