Week 4: Version control system

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# Version Control System
Eslam Adel

`eslam.a.mahmoud@eng.cu.edu.eg`

---

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## Outlines

* Overview & Problem definition
* Git version control system 
* Getting started with git 
    * Installation (local)
    * github.com 
* Work flow
    *  configuration
    * Initialize or clone repository 
    * Track files
    * Commit 
    * Update remote repository 
* Branches
    * Idea 
    * Create Branch 
    * merge branches
    * conflicts
---

## Overview & Problem definition

* Project Backup strategy  
    * Disk crash
    * Professional Work Archiving
        
        final, final1, final2, ... etc.
        
        What is the working file ?? 
    
    * Team work collaboration
        * Work on same source
        * Auto merging work
    
    * Record all changes
    * View all history of the project

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## Git Version Control System

* The most popular version control system 
* Supports parallel simultaneous development
* Handle huge number of users
* Branch development and easy merging 
* Others: SVN , Mercurial

![](../../images/w4/git.jpeg)

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## Getting Started 
* Installation
    * For linux 
    ```bash
    sudo apt-get install git
    ```
    * For windows install from [here](https://git-scm.com/downloads)

![](../../images/w4/install-win1.png)
    
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## Open the bash

![](../../images/w4/opengit.png)
    
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![](../../images/w4/bash-here.png)

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## Git and github

* create an account on [github](github.com) 
* github : remote server 
* git : local development
* Allow code sharing and team contribution

![](../../images/w4/github.png)

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## The work flow

![](../../images/w4/git-github.png)

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## Basic Illustration

![](../../images/w4/version-control-fig3.png)

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## Git cycle
* Configuration : one time after installation

```bash
git config --global user.email "example@mail.com"
git config --global user.mail "Name"
```

### Create or clone repository

* Repository is the source code of the project 
* Create empty repository 
```bash 
git init
```
* Clone existing one
```bash
git clone URL
```

* Showing repository status 
```bash
git status 
```
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## Tracking and Commit

* Tracking file content
```bash
git add filename
```
* ignore changes

```bash
git stash
```

### Commit

* Recording change in the repository 
* Snapshot of project at this state
* Records 
    * How was the change 
    * Who did it and when
    * The purpose of that change
```bash
git commit -m "Your message"
```

---

## Project Monitoring 
* Show history 
    ```bash 
    git log 
    ```
![](../../images/w4/commits.png)

```bash
    git show commitId
    ```

---

## Transition between states (commits)

Switch to a certain commit

```bash
git checkout commitId
```

Back to last commit

```bash
git checkout master
```

![](../../images/w4/checkout1.png)

---

## Publishing and sharing

* Updating local repository from master branch

```bash
git pull origin master 
```

* Publishing your commits on master branch

```bash
git push origin master
```

* Auto-merge is enabled

---

## Branches
* Separate line of development
* Used for 
    * Parallel development
    * Bug isolation and fix
    * Trying new idea 
* Finally branch is merged or deleted
![](../../images/w4/branch2.png)

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## Branched cont, 
* Create branch
```bash 
git checkout -b branch_name
```
* Show branches
```bash 
git show-branch
```
* Merge branch to master

```bash
git checkout master
git merge branch_name
```
![](../../images/w4/Branch-2.png)

---
 
## Merge Conflict

* Merging in case of same line is modified by through commits
* Example

![](../../images/w4/conflict.png)

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## Resources
    
* [Git Cheat Sheet](https://services.github.com/on-demand/downloads/github-git-cheat-sheet.pdf)

![](../../images/w4/cheatsheet1.png)
    
* interactive [learning git](https://learngitbranching.js.org/)