From Zero to your first PR with Git and Github

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# From Zero to your first PR with Git and Github

### Cesar Aguirre

_Software engineer, lifelong learner_

---

## Why?

_Have you ever done something like this?_

```bash
> ls

Project-2020-04-01/
Project-2020-04-02/
Project-2020-04-03/
Project-Final/
Project-Final-Revised/
Project-Final-Final/
Project-Final-Final-Final/
Project-ThisIsNOTTheFinal/
Project-ThisIsTheFinal/
```

You’re doing it wrong!

---

## Version Control System

From the book [Pro Git](https://git-scm.com/book/en/v2/Getting-Started-About-Version-Control):

_Version control is a system that records changes to a file or set of files over time so that you can recall specific versions later._

It allows to

* revert a file or an entire project to a previous state
* compare changes of a file over time
* see who modified something

---

## Version Control System: Analogy

![](https://upload.wikimedia.org/wikipedia/en/d/d2/Back_to_the_Future.jpg)

.footnote[Source: [Wikipedia](https://en.wikipedia.org/wiki/Back_to_the_Future)]

---

## Centralized vs distributed

### Centralized

.footnote[Source: [Pro Git](https://git-scm.com/book/en/v2/Getting-Started-About-Version-Control)]

---

## Centralized vs distributed

### Distributed

.footnote[Source: [Pro Git](https://git-scm.com/book/en/v2/Getting-Started-About-Version-Control)]

---

## Git: what is it?

* distributed version control system
* fast and lightweight
* free and open source
* flexible branch model
* developed by Linus Torvalds for the Linux kernel
* the most commonly used version control system today

.footnote[Sources: [Wikipedia](https://en.wikipedia.org/wiki/Git), [About Git](https://git-scm.com/about/branching-and-merging), [What is Git](https://docs.microsoft.com/en-us/azure/devops/learn/git/what-is-git)]

---

## How to install

Head to [Installing Git](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git)

On MacOs

```bash
$ brew install git
```

On Windows with [Chocolatey](https://chocolatey.org/)

```powershell
> choco install git.install
```

On Ubuntu

```bash
$ sudo apt-get update
$ sudo apt-get install git
```

---

## First-time setup

### Your identity

```bash
$ git config --global user.name "John Doe"
$ git config --global user.email johndoe@example.com
```

.footnote[Source: [First-Time Git Setup](https://git-scm.com/book/en/v2/Getting-Started-First-Time-Git-Setup)]

---

## How to start

### Create a new repo locally

```bash
$ git init
```

### Clone an existing repo

```bash
$ git clone <url>
```

For example, `$ git clone https://github.com/canro91/BaseXml`

---

## Saving changes

1. Create a file
```bash
$ echo 'This is a demo of Git basic concepts' >> README.md
```

2. Save your changes
```bash
$ git add README.md
$ git commit -m 'Add README file'
```

---

## Working dir/staging area/commit

.footnote[Source: [Pro Git](https://git-scm.com/about/staging-area)]

---

## Ignore files

There are files you don't want to track. For example: log files, files generated after building, folders generated by your IDE

Create a `.gitignore` file

```bash
[Bb]in/
[Oo]bj/
[Ll]og/
[Ll]ogs/
```

.footnote[[A collection of templates](https://github.com/github/gitignore), [More Ignore patterns](https://www.atlassian.com/git/tutorials/saving-changes/gitignore#ignoring-a-previously-committed)]

---

## Commit message style guide

_Are you commiting with messages like "Uploading changes"?_

A commit message should answer:

* Why is this change necessary?
* How does it address the issue?
* What side effects does this change have?

.footnote[Source: [5 Useful Tips For A Better Commit Message](https://thoughtbot.com/blog/5-useful-tips-for-a-better-commit-message)]

---

## Branches

_Create an alternate timeline to work without messing with the main line_

The default branch name is `master`

1. Create a branch
```bash
$ git branch testing
```

2. Move to the new branch
```bash
$ git checkout testing
```

Alternatively, you can combine these two commands into a single one

```bash
$ git checkout -b testing
```

---

## Merging

1. Move to the desired branch
```bash
$ git checkout master
```

2. Merge a branch
```bash
$ git merge testing
```

3. Delete a merged branch
```bash
$ git branch -d testing
```

---

## Merge and conflicts

If you modified the same parts of a file in different branches, Git won't be able to merge them cleanly. *Now you have a conflict.*

Git uses markers to delimit conflicted areas.

```bash
<<<<<<< HEAD
Some content
=======
Another content
>>>>>>> branch 
```

---

## Gitflow

.footnote[Source: [A successful Git branching model](https://nvie.com/posts/a-successful-git-branching-model/)]

---

## Sync

_What if you want your code to have a home outside your computer?_

You need a "remote". For example: GitHub, Gitlab and Bitbucket.

1. Add a remote
```bash
$ git remote add <name> <url>
```

2. Upload your changes
```bash
$ git push <branch> <remote>
```

For example, `$ git remote add origin https://github.com/canro91/GitDemo.git`

---

## Github

![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/95/Font_Awesome_5_brands_github.svg/54px-Font_Awesome_5_brands_github.svg.png)

Github is a hosting solution for Git, recently acquired by Microsoft. It's kind of a social network

* Unlimited private repositories
* Bug tracking
* Task management
* Wikis
* Follow developers
* Star projects
* Be part of communities

_Some people use their Github profile as CV_

.footnote[Sources: [Wikipedia](https://en.wikipedia.org/wiki/GitHub), [Your new resume](http://blog.gainlo.co/index.php/2015/11/13/how-to-make-github-as-your-new-resume/)]

---

## Pull Request

* A pull request is a request to include some changes from my fork into the original repo

* Fork means create an identical copy of a repo and become the owner

---

## Cheatsheet

* `git init`
* `git clone <url>`
* `git status`
* `git add <file>`
* `git commit -m 'A commit message'`
* `git log --oneline --graph`
* `git branch <branch-name>`
* `git checkout <branch-name>`
* `git merge <branch-name>`
* `git remote add <name> <url>`
* `git push origin <branch-name>`
* `git pull origin <branch-name>`

.footnote[More cheatsheets: [here](https://www.git-tower.com/blog/git-cheat-sheet/) and [here](https://education.github.com/git-cheat-sheet-education.pdf)]

---

## Let's Practice

* Install Git locally
* Create a Github account
* Open your first PR

Head to [firstcontributions/first-contributions](https://github.com/firstcontributions/first-contributions) and follow the instructions to open your first PR using either the command line or your favorite IDE.

---

## Want to know more?

* [C# Definitive Guide](https://canro91.github.io/2018/11/17/TheC-DefinitiveGuide/) Section about Git and Github
* [Git Guide for TFS Users](https://canro91.github.io/2019/11/11/GitGuideForTfsUsers/) If it happens you know TFS
* [Flight rules for Git](https://github.com/k88hudson/git-flight-rules) In case of panic
* [Pro Git](https://git-scm.com/book/en/v2) An entire book on the subject

---

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# That's all folks!

## Cesar Aguirre

https://canro91.github.io/

https://github.com/canro91