Notes for Git¶

约 897 个字预计阅读时间 3 分钟

一个自底向上的学习过程，最后附上了常用指令，暂无操作演示，可以参考原课程网站

Terminology¶

定义

blob: 一个文件被称作blob.
tree: 一个文件夹被称作tree.
commit: 整个仓库的快照被称作commit.
history: commit 的有向无环图构成history.
object: 一个object是 blob、tree 或者 commit，每个对象都有自己对应的 hash.
reference: 一个reference是一个对象的别名，除了别名，我们还可以通过 hash 来引用一个对象。
main/master: main/master 作为一个特殊的 reference 总是指向开发中的最新稳定版本。
HEAD: HEAD 作为一个特殊引用指向我们目前在历史中的位置。
Git repository: 一个 Git repository* 是 object 和 reference 的集合。
Staging area: Staging area 是一种机制来让我们指定哪些对象要被 commit，而非整个仓库。

Git Data Model¶

首先定义数据对象

// a file is a bunch of bytes
type blob = array<byte>

// a directory contains named files and directories
type tree = map<string， tree | blob>

// a commit has parents， metadata， and the top-level tree
type commit = struct {
    parents: array<commit>
    author: string
    message: string
    snapshot: tree
}

//An object is a blob，tree，or commit
type object = blob | tree | commit

在 Git 存储结构中，每个对象对应一个 hash

objects = map<string， object>

def store(object):
    id = sha1(object)
    objects[id] = object

def load(id):
    return objects[id]

Commands¶

Basic

git help <command> : get help for a git command
git init : creates a new git repo， with data stored in the .git directory
git status : tells you what’s going on
git add <filename> : adds files to staging area
git commit : creates a new commit
git log : shows a flattened log of history
git log --all --graph --decorate : visualizes history as a DAG
git diff <filename> : show the differences between current file and HEAD version file
git diff <revision> <filename> : shows differences between current file and specified snapshot
git diff <reversin> <reversion> <filename> shows the differences between two specified version of file
git checkout <revision> : updates HEAD and current branch
git checkout <filename> : erase all the changes we made after the HEAD version for this file
git cat-file -p <hash> : The instruction to catch a tree or blob

Branching and Merging

git branch: shows branches
git branch <name>: creates a branch
git checkout -b <name>: creates a branch and switches to it
same as git branch <name>; git checkout <name>
git merge <revision> : merges into current branch;wait for latter adjustments when conflictions occur(But the file has been changed already)
git merge --abort : erase the changes git try to make when an merge conflict occurs
git merge --continue : continue to merge after you fix the merge confliction
git mergetool: use a fancy tool to help resolve merge conflicts
git rebase: rebase set of patches onto a new base

Notes for Git¶

Terminology¶

Git Data Model¶

Commands¶

Comments