HEAD

HEAD is a tiny file that just contains the name of your current branch

.git/HEAD
ref: refs/heads/main

HEAD can also be a commit ID, that’s called “detached HEAD state”

branches

a branch is stored as a tiny file that just contains 1 commit ID. It’s stored in a folder called refs/heads.

7622629 - (actually 40 characters)

tags are in refs/tags, the stash is in refs/stash

commit

a commit is a small file containing its parent(s), message, tree, and author

.git/objects/7622629

tree c4e6559 
parent 037ab87 
author Julia <x@y.com> 1697682215 
committer Julia <x@y.com> 1697682215 
commit message goes here 

these are compressed, the best way to see objects is with git cat-file -p HASH

trees

trees are small files with directory listings. The files in it are called “blobs”

.git/objects/c4e6559

100644 blob e351d93 404.html 
100644 blob cab4165 hello.py
040000 tree 9de29f7 lib

the permissions here LOOK like unix permissions, but they’re actually super restricted, only 644 and 755 are allowed

blobs

blobs are the files that contain your actual code

.git/objects/cab4165
print("hello world!!!!")

reflog

the reflog stores the history of every branch, tag, and HEAD

.git/logs/refs/heads/main

2028ee0 c1f9a4c 
Julia Evans <x@y.com> 
1683751582 
commit: no ligatures in code

each line of the reflog has: - before/after commit IDs - user + - timestamp - log message

remote-tracking branches

remote-tracking branches store the most recently seen commit ID for a remote branch

.git/refs/remotes/origin/main
a9bbcae

when git status says “you’re up to date with origin/main”, it’s just looking at this

.git/config

.git/config is a config file for the repository. it’s where you configure your remotes

.git/config

[remote "origin"] 
url = git@github.com: jvns/int-exposed 
fetch = +refs/heads/*: refs/remotes/origin/* 
[branch "main"] 
remote = origin 
merge refs/heads/main

git has and local global settings, the local settings are here and the global ones are in ~/.gitconfig

hooks

hooks are optional scripts that you can set up to run (eg before a commit) to do anything you want

.git/hooks/pre-commit

#!/bin/bash 
any-commands-you-want

the staging area

the staging area stores files when you’re preparing to commit

.git/index
(binary file)