GitHub Tutorial

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# Hands-on GitHub Tutorial

### Introduction to Git and GitHub

<br><br><br><br><br><br>
.h4[Javed Ali]

Graduate Research Assistant & PhD Student

Dept. of Civil, Environmental & Construction Engineering

University of Central Florida, USA

<br><br>
.h5[(31 July 2022)]

.pull-right[
<br><br><br>
.footnote[Slides:
<a href="https://tinyurl.com/intro-git-slides"><i class="fa fa-github fa-fw"></i>&nbsp; https://tinyurl.com/intro-git-slides</a>

]
]

---
# Has this happened to you?

---

# This tutorial is for you

<br>

.pull-left[
.h4[If you want to get started with Git **now**.]

Here, we will focus on the tools you _actually_ need to start working collaboratively and putting your work under version control.

Git is extremely powerful and there are myriad sophisticated things you can do with it. As a result, the [<svg aria-hidden="true" role="img" viewBox="0 0 448 512" style="height:1em;width:0.88em;vertical-align:-0.125em;margin-left:auto;margin-right:auto;font-size:inherit;fill:#d49a89;overflow:visible;position:relative;"><path d="M448 360V24c0-13.3-10.7-24-24-24H96C43 0 0 43 0 96v320c0 53 43 96 96 96h328c13.3 0 24-10.7 24-24v-16c0-7.5-3.5-14.3-8.9-18.7-4.2-15.4-4.2-59.3 0-74.7 5.4-4.3 8.9-11.1 8.9-18.6zM128 134c0-3.3 2.7-6 6-6h212c3.3 0 6 2.7 6 6v20c0 3.3-2.7 6-6 6H134c-3.3 0-6-2.7-6-6v-20zm0 64c0-3.3 2.7-6 6-6h212c3.3 0 6 2.7 6 6v20c0 3.3-2.7 6-6 6H134c-3.3 0-6-2.7-6-6v-20zm253.4 250H96c-17.7 0-32-14.3-32-32 0-17.6 14.4-32 32-32h285.4c-1.9 17.1-1.9 46.9 0 64z"/></svg> documentation](https://git-scm.com/book/en/v2) is very thorough, but can often be overwhelming 🤯 if you are just starting.
]

.pull-right[
<img src="https://octodex.github.com/images/Professortocat_v2.png">
]

---
# Why you should use Git

.h4[To be kind to yourself]

.h4[To be kind to your collaborators]

.h4[To ensure your work is reproducible]

<br>

--
### Spillover benefits

👨‍🔬 📐 It imposes a certain discipline to your programming.

🤓 🔥 You can be braver when you code: if your new feature breaks, you can revert back to a version that worked!

👩‍💻 🗳 Keeps multiple (older and newer) versions of everything (not just source code)

---
## Revert back to the last working stage

---
# Git and GitHub

.h4[Git]

- the software that allows us to do version control.

- like the “Track Changes” feature from Microsoft Word, but more rigorous, powerful, and scaled up to multiple files.

.h4[GitHub]

- hosting service for git projects — essentially Dropbox for git projects.

- You can host **remote** repositories on https://github.com/. You edit and work on your content in your **local** repository on your computer, and then you send your changes to the remote.

You can interact with Git using the **Graphical User Interface (GUI)** provided by GitHub Desktop, or through the **Command Line Interface (CLI)**.

.h4[In this tutorial, we will use both.]

---
background-image: url(assets/remote-local.png)
background-size: contain

---
## [GitHub](https://github.com/) Walkthrough

---
# Installation (GUI)

Install GitHub Desktop from <https://desktop.github.com/>.

---
# Installation (CLI)

.pull-left[
<br>

.h4[Git for Windows]

https://gitforwindows.org/

<br>

.h4[MacOS]
	 
https://tinyurl.com/git-mac

(Alternate: `brew install git`)

]

<br>

.pull-right[
<div class="card">
	<img src="https://gitforwindows.org/img/gwindows_logo.png" alt="Card Back">
    <img src="https://gitforwindows.org/img/git_logo.png" class="img-top" alt="Card Front">
</div>
]

---
# Setting up git environment

<br>

.h4[As a first-time set up, you need to tell Git who you are.]

Enter these lines (with appropriate changes):

```bash
git config --global user.name "Javed Ali"
git config --global user.email "javedali@knights.ucf.edu"
```

- Make sure that you include here the same email you used for signing up on GitHub.

Test if this worked by typing

```bash
git config --list
```

.h4[You only need to do this once.]

---
# SSH key generation & setup

--
**Step 1.** Check if your computer is already connected to GitHub

```bash
ssh -T git@github.com
```
- If it gives an error, then you're not connected.

<br>

**Step 2.** Check what key pairs already exist on your computer.

```bash
ls -al ~/.ssh
```
- If SSH has been set up on the computer you’re using, the public and private key pairs will be listed. The file names are either `id_ed25519`/`id_ed25519.pub` or `id_rsa`/`id_rsa.pub` depending on how the key pairs were set up.

**Step 3.** If they don’t exist on your computer, use this command to create them.

```bash
ssh-keygen -t ed25519 -C "your email address"
```

---
<br><br><br>

**Step 4.** Now that we have generated the SSH keys, we will find the SSH files when we check.

```bash
ls -al ~/.ssh
```
<br>
--

**Step 5.** Copy the public key to GitHub

```bash
cat ~/.ssh/id_ed25519.pub
```
<br>
--

**Step 6.**  Now that we’ve set that up, let’s check our authentication again from the command line.

```bash
ssh -T git@github.com
```

It should say,

```bash
Hi <Your Name>! You have successfully authenticated, but GitHub does not provide shell access.
```

---
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# Using GitHub Desktop

---
# The basic workflow

### First time
1. **Clone** the repository that you want to work on from GitHub onto your local machine

2. Work on the files/scripts

3. Next, you will **commit** your changes and include an informative message, e.g. "Plot distribution of precipitation"

4. Then, you will **push** your changes to the remote repository

### Subsequent times
1. **Pull** any changes from the remote repository that your collaborators might have made

2. Repeat steps 2-4 above

---

# Working with GitHub

<br>

There are two ways to work with GitHub projects.

**Type 1:**

- Create the repository on GitHub, clone it to your PC, and work on it. **(Recommended)**

<br>

**Type 2:**

- Work on your project locally then create the repository on GitHub and push it to remote.

---
# Create a repo on GitHub

---
# Cloning

---
# Work on local repo

---
# Commit your changes

---
# Commit your changes

.h4[Use an informative commit message]
  - (Not great) "Analyze data" 😞
  - (Better) "Estimate logistic regression" 🎉

.h4[Have a consistent style]
  - Start with an action verb
  - Capitalize message

.h4[Commits are _cheap_, use them often!]

---
# Tracking files

---
# Push your changes

---
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# Using the command line (CLI)

---

# Working on local machine

.h4[Clone the repository]

```bash
git clone URL
```

```bash
git clone https://github.com/javedali99/git-tutorial.git
```

.h4[Stage your files]
```bash
git add .
```

.h4[Commit your changes]
```bash
git commit -m "Add example code"
```

.h4[Push your changes]
```bash
git push
```

---
# Adding your files to git repository

---
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# More command line tips

---
# git status

.h4[Use this to check at what stage of the workflow you are at.]

_This happens when you have modified the script, but haven't staged your changes yet._

```bash
git status
```

```bash
*Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)
*        modified:   file.py
no changes added to commit (use "git add" and/or "git commit -a")
```

---
# git status

_After you stage the `file.py` file, but before you commit the changes._

```bash
git add file.py
git status
```

```bash
*Changes to be committed:
  (use "git reset HEAD <file>..." to unstage)
        modified:   file.py
```

.h4[When your local repository is in sync with the remote.]

```bash
git status
```

```bash
On branch master
Your branch is up to date with 'origin/main'.
*nothing to commit, working tree clean
```

---
# git pull

Your collaborators have been adding some awesome content to the repository, and you want to fetch their changes from the remote and update your local repository.

.h4[Use this to fetch changes from the remote and to merge them in to your local repository.]

```bash
git pull
```
What this is doing under-the-hood is running a `git fetch` and then `git merge`.

---
# Adding and ignoring files

To stage specific files in your repository, you can name them directly

```bash
git add file.py other-script.py
```
or you can add all of them at once

```bash
git add .
```

You might want to _not_ track certain files in your local repository, e.g., sensitive files such as credentials. But it might get tedious to type out each file that you _do_ want to include by name.

.h4[Use a .gitignore file to specify files to always ignore.]

Create a file called `.gitignore` and place it in your repo. The content of the file should include the names of the files that you want Git to **not track**.

---
# git log

.h4[Use this to look at the history of your repository.]

Each commit has a specific **hash** that identifies it.

```bash
git log
```

```bash
*commit af58f79bfa4301643025dd6c8767e65349cf407a
Author: Name <Email address>
Date:   DD-MM-YYYY
    Add file script
```

You can also find this on GitHub, by going to [github.com/user-name/repo-name/commits](https://github.com/javedali99/git-tutorial/commits).

.h4[You can go back in time to a specific commit, if you know its reference.]

---
# Undoing mistakes

Imagine you did some work, **committed** the changes, and **pushed** them to the remote repo. But you'd like to undo those changes.

.h4[Running `git revert` is a "soft undo".]

Say you added some plain text by mistake to `file.py`. Running `git revert` will do the opposite of what you just did (i.e., remove the plain text) and create a new commit. You can then `git push` this to the remote.

```bash
git revert <hash-of-the-commit-you-want-to-undo>
git push
```

---
# Undoing mistakes

`git revert` is the safest option to use.

.h4[It will preserve the history of your commits.]

```bash
git log
```

```bash
commit 6634a076212fb7bac16f9525feae1e83e0f200ca
Author: Name <Email address>
Date:   DD-MM-YYYY
*    Revert "Add plain text to code by mistake"
*    This reverts commit a8cf7c2592273ef6a28920222a92847794275868.
commit a8cf7c2592273ef6a28920222a92847794275868
Author: Name <Email address>
Date:   DD-MM-YYYY
    Add plain text to code by mistake
```

---
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# Other resources

---
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# Other Git resources

#### [Version Control with Git](http://swcarpentry.github.io/git-novice/)
#### [GitHub Git Cheatsheet](https://github.github.com/training-kit/downloads/github-git-cheat-sheet/)
#### [Learn Git Branching in Visual and Interactive Way](https://learngitbranching.js.org/)
#### [Pro Git book](https://git-scm.com/book/en/v2)
#### [Happy Git and GitHub for the useR](https://happygitwithr.com/)
#### [Git Cheatsheet](https://ndpsoftware.com/git-cheatsheet.html)
#### [W3School Git Tutorial](https://www.w3schools.com/git/)

---
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## .white[Links]

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.h4[.accent[<i class="fa fa-envelope"></i>]<a href="mailto:javedali@knights.ucf.edu">.accent[&nbsp;&nbsp;javedali@knights.ucf.edu]</a>]

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