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# Automated Version Control
What is version control and why should I use it?
Note:
- Git all set up?
- SSH working?
- Otherwise: breakout room
===
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<img style="height: 70vh;" src="https://swcarpentry.github.io/git-novice/fig/phd101212s.png"/>
<span style="font-size: small;">“Piled Higher and Deeper” by Jorge Cham, http://www.phdcomics.com </span>
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## Documents are...
<div class="fragment">
a series of changes
<img style="height: 30vh; margin: 0; padding: 0;" src="https://swcarpentry.github.io/git-novice/fig/play-changes.svg"/>
</div>
===
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## Collaboration
<div style="float: left; width: 49%;">
independent changes
<img style="height: 350px;" src="./media/versions.svg"/>
</div>
<div class="fragment" style="float: right; width: 49%;">
can be merged
<img style="height: 350px;" src="./media/merge.svg"/>
</div>
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## Version Control: Key Points
- Version control is track changes on steroids.
- Version control is like an unlimited **undo**.
- Version control also allows many people to work in parallel.
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## The Holy Realms of Git
<img src="https://swcarpentry.github.io/git-novice/fig/git-staging-area.svg">
<ul>
<li><b>workspace</b> 📂</li>
<ul>
<li>Your filesystem</li>
</ul>
<li class="fragment"><b>index</b> 🕒
<ul>
<li>Staging area</li>
<li>Files wait patiently to be committed</li>
</ul>
</li>
<li class="fragment"><b>local repository</b> 🗂️
<ul>
<li>Contains branches, commits, history, etc.</li>
</ul>
</li>
<ul>
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## Crowded Staging Area / Index
<img src="https://swcarpentry.github.io/git-novice/fig/git-committing.svg">
The Staging Area / Index can hold many files and folders.
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## Quiz 1/2
<blockquote style="text-align: left;">
Which commit message should I choose?
<ol>
<li>“Changes”</li>
<li>“Added line ‘This project started as a joke’ to myfile.txt”</li>
<li>“Discuss origin of the project”</li>
</ol>
</code></pre>
</blockquote>
<blockquote class="fragment" style="text-align: right;">
Make it short, descriptive, and imperative <span style="font-style: normal;">🐺</span>
</blockquote>
<blockquote class="fragment" style="text-align: right;">
So yeah, the last one is good! <span style="font-style: normal;">🐺</span>
</blockquote>
===
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## Quiz 2/2
<blockquote style="text-align: left;">
Which command saves <b>myfile.txt</b> to my Git repo?<br>
<ol>
<li>
<pre style="width: 100%; font-style: normal;" data-id="code-animation"><code data-trim class="bash">
$ git commit -m "my recent changes"
</code></pre>
</li>
<li>
<pre style="width: 100%; font-style: normal;" data-id="code-animation"><code data-trim class="bash">
$ git init myfile.txt
$ git commit -m "my recent changes"
</code></pre>
</li>
<li>
<pre style="width: 100%; font-style: normal;" data-id="code-animation"><code data-trim class="bash">
$ git add myfile.txt
$ git commit -m "my recent changes"
</code></pre>
</li>
<li>
<pre style="width: 100%; font-style: normal;" data-id="code-animation"><code data-trim class="bash">
$ git commit -m myfile.txt "my recent changes"
</code></pre>
</li>
</ol>
</code></pre>
</blockquote>
<blockquote class="fragment" style="text-align: right;">
3. adds your file to the index, and then commits it. That's the one.
<span style="font-style: normal;">🐺</span>
</blockquote>
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## Tracking Changes: Key Points
- Files can be stored in
- **working directory**: the files you can see
- **staging area / index**: files about to be committed
- **local repository**: the permanent record
- **git status** shows the status of a repository
- **git add** puts files in the staging area
- **git commit** saves the staged content as a new commit in the local repository
- Write short, descriptive, and imperative commit messages
===
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## Exploring history
<img src="https://esciencecenter-digital-skills.github.io/git-lesson/fig/git-restore.svg">
Use `git restore` with the `-s` option to retrieve a specific state.
Note:
In this example we restore to the state before the most recent commit,
which is `HEAD~1` or `f22b25e`
