# The Basics of Git
## Craig Reeder
---

# Who am I?

Craig Reeder

Senior Cloud Engineer @ *Uturn Data Solutions*

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# I love tooling

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# I *really* love tooling

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# Git is one of my favorite tools

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# What is Git?

Distributed Version Control Software

---
# History

Created by Linus Torvalds in 2005

*(To manage Linux source code)*

Note:
Though it's been largely developed by others since

---
# Quick Note: GitHub

GitHub is just a hosted platform for Git repositories

---

![](assets/burger-king.svg)

Git is to GitHub as Burgers are to BurgerKing

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# What does git *do*?

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# Tracks changes

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# Keeps history

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# Enables collaboration

Everyone has a full copy

Note:
This has proved useful for recovery purposes

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# Why use git?

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# Ever done this?

```
project/
    config-4.3.20
    config-1.5.21
    config-7.8.21
    config-live
```

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# Never do that again!

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# Git has history

All changes
*(since the beginning of time)*

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# Easily reversable

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# Who broke it?

```
$ git log

Author: Travis Langhals <tlanghals@example.com>
Date:   Fri Sep 3 12:13:57 2021 -0400

Remove the Fizz from the Buzz, it's not needed
```

*(spoiler alert: it was needed)*

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# Great! How do I use it?

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# Creating a new repository

```bash
$ git init
```

Note:
This creates a new repository in the current directory

---
# Time to make some changes

![](assets/cat.gif)

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# Staging Changes

To save your changes, you need to tell git you want to include them

Note:
This feels silly, but this means that you can select which changes to actually save, or break them into smaller chunks

---
# Stage your changes

```bash
$ git add foo.html bar.js
```

---
# Commit your changes

```bash
$ git commit
```

This will prompt you in an editor for a message.

*(It is possible to change which editor it uses.)*

---

![](assets/vim.png)

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# Don't have commitment issues

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# Commit early and often

![](assets/easy.jpg)

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# It's not that easy! I got lost!

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# Check status

```bash
$ git status
```

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# Status Output

```
On branch main
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
  modified:   index.html
  modified:   themes/dark.css
```

---
# Working locally
## A cheat sheet

```bash
$ git init # once, for a new repo

# make changes to files
$ git add file.txt
$ git commit
```

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# Now let's work as a team

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# Getting an existing repository

```bash
$ git clone git@github.com:torvalds/linux.git
```

---
# Quick Note: Auth

SSH:
```bash
$ git clone git@github.com:torvalds/linux.git
```

HTTPS:
```bash
$ git clone https://github.com/torvalds/linux.git
```

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# Clone URL Selection

![](assets/clone-url.png)

Select it here on GitHub

---
# SSH vs HTTPS

- SSH relies on the key you already created
- HTTPS will prompt you for credentials every time
  *(Unless you set up a credential manager)*
- SSH works better with most automation

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# Back to the commands

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# Getting updates

Someone made a change to a repository you cloned

*Oh no! What do I do? 😢*

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# Pull changes from remote

```bash
$ git pull
```

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# Now you're up to date!

![](assets/cat.gif)

---
# Stage your changes

```bash
$ git add foo.html bar.js
```

---
# Commit your changes

```bash
$ git commit
```

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# Commiting is local only

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# Share your changes

```bash
$ git push
```

Note:
The first time you do this in a branch, you'll get an error message with an additional flag. Follow the instructions.

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# One more important concept

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# Git is a tree

![](assets/git-tree.png)

*(sometimes displayed sideways)*

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# Trees have branches

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# Git has branches!

![](assets/git-tree.png)

*(and a trunk)*

Note:
You'll hear tree terminology used a lot around git

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# Default branch

The default branch is usually *main*

*(Sometimes it's called "master")*

Note:
It'll be master if you init on your machine. This is a simple configuration option.

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# Create a new branch

```bash
$ git branch widget-fix
```

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# Change to a branch

```bash
$ git checkout widget-fix
```

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# Merging

Merging is the act of combining branches

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# We're not going to cover manually merging

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# Pull Requests

With most hosted Git platforms, you can create a pull request

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# What's that?

This is a request to merge your branch into another

*(Typically main)*

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# Review!

Best practice with a pull request is to have someone else review your code

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# GitHub has useful commenting and approval tools

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# Let's talk about flows

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# Github Flow

1. Make a feature branch
2. Make your changes
3. Commit your changes
4. Push your changes
5. Make a Pull Request
6. Fix any feedback from review (repeat 2-4)
7. Merge the PR

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# Step 1: Make a feature branch

```bash
$ git branch widget-fix
$ git checkout widget-fix
```

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# Step 2: Make your changes

![](assets/cat.gif)

---
# Step 3: Commit your changes

```bash
$ git add fixed-files.txt
$ git commit
```

---
# Step 4: Push your changes

```bash
$ git push
```

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# Step 5: Make a PR

![](assets/pr.png)

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# Step 6: Fix feedback

Fix any feedback from reviews

*(And repeat steps 2-4: make changes, commit, push)*

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# Step 7: Merge the PR

![](assets/merge-pr.png)

*(The final reviewer will likely do this step)*

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# GitHub Flow Summary

1. Make a feature branch
2. Make your changes
3. Commit your changes
4. Push your changes
5. Make a Pull Request
6. Fix any feedback from review (repeat 2-4)
7. Merge the PR

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# Some final thoughts

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# VSCode is git aware

Note:
It will show you what has changed since your last commit

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# VSCode Integration

All of the git commands can be done in VSCode with context menus

*(Look for the "source control" icon on the left)*

Note:
While I prefer the commandline, this is an easy way to get started.

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# .gitignore

*.gitignore* is a special file that tells git which files to ignore.

Those files won't ever be staged or commited

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# Questions?

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# Now for some hands on!

Try these commands (or do the following in VSCode):

```bash
$ git init # once, for a new repo
$ git add file.txt # create file.txt first
$ git commit
$ git status
$ git branch widget-fix
$ git checkout widget-fix

$ git clone <url> # new repo! get this from github
$ git branch your-username
$ git checkout your-username
$ git add file.txt # create file.txt first
$ git commit
$ git push # follow the instructions
```

---
# Thank you!