Git introduction

for beginners

Aaron Wang

What's git

A distributed version control system
A content-addressable file system
A stupid content tracker
Write code
Write book: https://www.gitbook.io/
Started by Linus Torvalds for Linux kernel development @ 2005

Git characteristics

Distributed & Decentralized, client == server
Fast Branching & Merging
Efficient In Storage & Network
Toolkit Based Design

Over a hundred commands, countless options...

Flexible Workflow

Local operations

Git Directory
Working Directory
Index(Stage/Cache)

get started

git help <command>
git config --global user.name <name>
git config --global user.email <email>
.git/config > ~/.gitconfig > /etc/gitconfig
git init/git clone <url>
git status, git diff
git add, git diff --cached
git commit -m <message>
.gitignore: https://github.com/github/gitignore
git log

What's a good commit

http://dev.solita.fi/2013/07/04/whats-in-a-good-commit.html
Small & Complete
Commit message:
<scope>: <short summary>
\n
<detail>
Take it seriously, form a good habit
Commit Often & Commit Early

Revert changes

uncached: git checkout <paths>
cached: git reset <tree-ish> -- <paths>
committed:

git reset <tree-ish> -- <paths>; git checkout <paths>
git reset <commit> --hard
git revert <commit>

Remote Operations

git clone <url>

https://github.com/git/git.git
ssh

scp style: git@github.com:git/git.git
ssh://git@github.com/git/git.git

/home/git/git.git
git://github.com/home/git/git.git

git remote
git pull == git fetch + git merge
git pull --rebase == git fetch + git rebase
git push

Understanding branch

git checkout -b <name>
git branch
git checkout -t <remote>/<branch>
git merge <name>[, solve conflicts, git commit]
Branch is just a ref to a commit
It moves
X --- Y --- Z
/ \
A --- B --- C --- D --- H
git push <remote> <src>:<dst>
git push <remote> :<dst>

Data Model

Directed Acyclic Graph

glossary

https://www.kernel.org/pub/software/scm/git/docs/gitglossary.html
object: the unit of storage
blob: file content
tree: like directory
commit: ref to a tree with metadata
branch: active line of development
tag: static, ref to a particular point
HEAD: the current branch, .git/HEAD

GLOSSARY

dangling: unreachable
detached: arbitrary commit in HEAD, not a particular branch
dirty: uncommitted modifications
fast-forward: no merge commit is needed
hash: object name
ref: SHA1 or name, .git/refs/
tree-ish: a ref pointed to either a commit object, a tree object, or a tag object
......

Centralized workflow

Like the other VCSs
"Better not use git as svn!"

Feature Branch

Develop features in separated branch
pull/merge requests

gitflow

http://nvie.com/posts/a-successful-git-branching-model/

gitflow

apt-get install git-flow
git flow init
git flow feature start/finish <name>
git flow release start/finish <name>
git flow hotfix start/finish <name>

tuisongbao dev process

git fetch
git checkout -t origin/develop -b whatsThisBranchFor
# Coding...
# Fetch new code on origin/develop in the middle
git stash
git pull --rebase
git stash pop
# Coding...
git add && git commit
git pull --rebase
git push origin whatsThisBranchFor -f

Quick tips

Conquer Git

Read The Output & RTFM
Read books, systematic learning
Practice

git stash: anonymous commit
committed/stashed changes are recoverable

git reflog
git cherry-pick

apt-get install gitk git-extras
Display git status in your command prompt

Customize PS1
Use oh-my-zsh plugin

References

https://github.com/inetfuture/technote/blob/master/git.md

HOMEWORK

merge vs rebase

git rebase -i

merge algorithom (optional)

What's gitlab

An open source copy of GitHub
Self hosted git management application

Users / Groups / Projects
Access Control
Merge Request / Code Review
Web Hooks
GitLab Flavored Markdown
Simple Issue Tracker
Simple Wiki System

How gitlab works

Tuisongbao code review process

Committer rebase feature branch onto to newest develop branch & push it to GitLab
Open a merge request to develop branch & assign to code reviewer
Reviewer do the code reivew

Point out issues: inconsistent coding style/convention, incorrect logic, missed edge case check, code smell, etc
Learn good parts from it
Knowing what the committer is working on, how is it going

Committer fix issues until reviewer is satisfied
Reviewer reassign the MR to develop branch maintainer
Maintainer merge it in

Markdown

A lightweight markup language
Textile/BBCode/MediaWiki => HTML
Created by John Gruber and Aaron Swartz
Flavors:

PHP Extra
StackOverflow
GitHub
GitLab
http://git.augmentum.com.cn/help/markdown

Thanks

Git introduction for beginners Aaron Wang

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