# Git Tutorial!
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Distributed Version Control System
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## Why a Version Control System like Git is needed
- Real life projects generally have multiple developers working in parallel. So a version control system like Git is needed to ensure there are no code conflicts between the developers.
- projects which are being run in parallel involve the same codebase
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### More than 70% of developers use Git. Developers :heart: Git.
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### commit
----
----
```shell=
git commit
```
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---
### branch
> 早點建立branch
> 經常建立bracnh
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----
```shell=
git branch newImage
# newImage - branch name
```
----
----
```shell=
git commit
# 現在還是在master上
```
----
```shell=
git checkout newImage #切換到newImage了
git commit #現在在newImage上
```
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補充
```shell=
git checkout -b bugFix #建立分支同時跳過去該分支
```
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### merge
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----
```shell=
git merge bugFix #現在我們在master上，所以是站在master上面去把bugFix "合併過來" 英文可以想成 merge from
```
----
```shell=
git checkout bugFix
git merge master
#猜猜看會發生什麼？
```
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### Q:
----
----
wait for 3 min.
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Answer
```shell=
git checkout -b bugFix # or git branch bugFix; git checkout bugFix
git commit #現在我們在bugFix上 [C2]
git checkout master #回到master [C1]
git commit #[C3]
git merge bugFix #merge from bugFix
```
Q: 請問bugFix有C3的內容嗎？
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### rebase (少使用)
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> 優點：讓repository tree較為美觀，但專案使用以merge為主
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----
```shell=
git rebase master #我們在bugFix上，把自己貼到master現在的點上面
```
----
```shell=
git checkout master
git rebase bugFix
```
> [C3]並沒有消失！
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### about remote
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---
### clone
----
----
```shell=
git clone repositoryURL
```
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## 關於 remote 命名
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### fetch (更新remote)
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----
> 左邊的tree代表local | 右邊的tree代表remote端
```shell=
git fetch
```
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> git fetch 通常是透過網路來跟 remote 溝通（透過一個 protocol （協定），例如 http:// 或者是 git://）
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`fetch` 會下載同步所需的資料，但是不會更新任何的檔案
可以把 `git fetch` 想成是在下載資料
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### pull
----
----
```shell=
git fetch
git merge o/master
```
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同等於執行
```shell=
git pull
```
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### push
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與 pull 相反。git push 負責上傳你的 commit 到特定 remote 上面並且做出相對應的更新，只要做完了 git push，所有你的team member都可以從 remote 上面下載你所送出去的 commit。
你可以把 git push 當作是一個"發佈"你的工作進度的指令
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```shell=
git push
```
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----
`git push` 僅針對於現在的分支＆remote的分支
若需要對其他branch push 除了checkout 到該分支以外 還有以下做法
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### 關於 diverged & conflict
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----
圖例
remote C2 -> 別的同事的push code
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solution 1:
```shell=
git fetch
git rebase o/master
git push
#同等於
git pull --rebase
git push
```
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solution 2:
----
solution 2:
```shell=
git fetch
git merge o/master
git push
#同等於
git pull
git push
```
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### 實務範例
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類型1
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branch side1 / side2 / side3 都想要推code到 remote master，且remote master已經領先一個commit [C8]
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```shell=
git checkout master
git pull
git rebase master side1
git rebase side1 side2
git rebase side2 side3
git rebase side3 master
git push
```
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----
類型2
----
```shell=
git checkout master
git pull
git merge side1
git merge side2
git merge side3
git push
```
----
----
> gitlab github 使用MR (merge request) 較為常見
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# :bulb: source tree
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---
### Thank you! :sheep:
By Kaya
- source: self & [gitplayground](https://learngitbranching.js.org/)
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