# Basics
# .git目录
$ git init
Initialized empty Git repository in D:/yiki/git-test/.git/
$ ls -al
total 8
drwxr-xr-x 1 xinbao 197121 0 Nov 2 13:59 ./
drwxr-xr-x 1 xinbao 197121 0 Nov 2 13:59 ../
drwxr-xr-x 1 xinbao 197121 0 Nov 2 13:59 .git/
$ cd .git
$ ls
config hooks/ info/ objects/ HEAD description index logs/ refs/
------------------------
./git
├── HEAD points to the branch you currently have checked out
├── index Git stores your staging area information
├── branches
├── config project-specific configuration options /邮箱/用户名 --- git cofig...
├── description used only by the GitWeb program
├── hooks hook scripts, which are discussed in detail in Git Hooks. --- pre-push
│ ├── pre-commit.sample
│ ├── pre-push.sample
│ └── ...
├── info
│ └── exclude global exclude file for ignored patterns --- .gitignore
├── objects core
│ ├── info
│ └── pack
└── refs pointers into commit objects in that data (branches, tags, remotes and more)
├── heads
└── tags
└── remotes
- file
config
$ cat config
[core]
repositoryformatversion = 0
filemode = false
bare = false
logallrefupdates = true
symlinks = false
ignorecase = true
# objects
TIP
Git is a content-addressable(内容寻址) filesystem. It means that at the core of Git is a simple key-value data store. What this means is that you can insert any kind of content into a Git repository, for which Git will hand you back a unique key you can use later to retrieve that content.
- 每次你创建一个文件，并追踪它，git 都将把文件进行压缩并存储在自己的数据结构中。
- 被压缩的对象将具有唯一的名称和 hash 值，并将存储到对象 (object) 目录中，此目录中每个文件都是
SNAPSHOT（快照） - git中每一个实体以一个
40字符长度的十六进制字符串来唯一标识
MINGW64 /d/yiki/git-test/.git
$ ls objects
info/ pack/
MINGW64 /d/yiki/git-test/.git
$ cd ..
MINGW64 /d/yiki/git-test (master)
$ touch 1.text
MINGW64 /d/yiki/git-test (master)
$ git add .
MINGW64 /d/yiki/git-test (master)
$ git commit -m 'add1'
[master (root-commit) cd1aeaf] add1
1 file changed, 0 insertions(+), 0 deletions(-)
create mode 100644 1.text
MINGW64 /d/yiki/git-test (master)
$ ls .git/objects
a5/ cd/ e6/ info/ pack/ // 多了a5-tree/ cd-commit log/ e6-file/
...
MINGW64 /d/yiki/git-test
$ find .git/objects -type f
.git/objects/70/30efb5d07c73bd6e4885c9686760eb6e6edc9c
.git/objects/a5/6bcbd1b3681262c1b2023d3cbf765c37d8a4d8 // a5-tree
.git/objects/cd/1aeaf5a4f969673aeb385d211e2615c4f6e280 // cd-commit log
.git/objects/e3/6dc774e5546c8ea5bf9687447a3b95d14caa12
.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391 // blob SHA1
git cat-file -pOnce you have content in your object database, you can examine that content with the git cat-file command，-pfigure out the type of content,- after ur commit
MINGW64 /d/yiki/git-test (master)
$ git log
commit cd1aeaf5a4f969673aeb385d211e2615c4f6e280 (HEAD -> master)
Author: liyiki <liyiqi@xinpayroll.com>
Date: Tue Nov 2 14:14:48 2021 +0800
add1
MINGW64 /d/yiki/git-test (master)
$ git cat-file -p cd1aeaf5a4f969673aeb385d211e2615c4f6e280
// 得到以下内容
tree a56bcbd1b3681262c1b2023d3cbf765c37d8a4d8 //快照的哈希值
author liyiki <liyiqi@xinpayroll.com> 1635833688 +0800 //作者信息和提交的注释
committer liyiki <liyiqi@xinpayroll.com> 1635833688 +0800
add1
// 查看快照 是我们添加的文件
MINGW64 /d/yiki/git-test (master)
$ git cat-file -p a56bcbd1b3681262c1b2023d3cbf765c37d8a4d8
100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 1.text
# HEAD
- 指向你正在使用的分支的顶端的指针
- Git有一种特殊的引用，称为
符号引用（Symbolic References） HEAD就是一个符号引用
$ cat HEAD
ref: refs/heads/master
- 分支 ( branch) 和标签 (tag) 只不过是一个指向提交的指针。这就意味着，即使你删掉了你要删除的分支和标签，他们指向的提交依然还在那里，只不过删除后难获取这些提交更困难一些
# ref
TIP
it would be easier if you had a file in which you could store that SHA-1 value under a simple name so you could use that simple name rather than the raw SHA-1 value.
# summary
- 每个commit都是git仓库的一个
快照- commit是对象关系图的入口
- tree对象用于描述目录结构，每个目录节点都会用一个tree对象表示。目录间、目录文件间的层次关系会在tree对象的内容中体现
- 每个commit都会有一个root tree对象
- blob对象为tree的叶子节点，它的内容即为文件的内容
- when you run the
git addandgit commitcommands, it...- stores blobs for the files that have changed
- updates the index(for staging area)
- writes out trees
- writes commit objects that reference the top-level trees
