113 lines
4.0 KiB
HTML
113 lines
4.0 KiB
HTML
---
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layout: reference
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---
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<div class="box">
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<h2>Introduction to the Git Reference</h2>
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<div class="block">
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<p>
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This is the Git reference site. This is meant to be a quick
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reference for learning and remembering the most important and
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commonly used Git commands. The commands are organized into
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sections of the type of operation you may be trying to do, and
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will present the common options and commands needed to accomplish
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these common tasks.
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</p>
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<p>
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Each section will link to the next section, so it can be used
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as a tutorial. Every page will also link to more in-depth
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Git documentation such as the official manual pages and relevant
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sections in the <a href="http://progit.org">Pro Git book</a>,
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so you can learn more about any of
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the commands. First, we'll start with thinking about source code
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management like Git does.
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</p>
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</div>
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</div>
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<div class="box">
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<h2>How to Think Like Git</h2>
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<div class="block">
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<p>
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The first thing that is important to understand about Git is
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that it thinks about version control very differently than
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Subversion or Perforce or whatever SCM you may be used to. It
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is often easier to learn Git by trying to forget your assumptions
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about how version control works and try to think about it in the
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Git way.
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</p>
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<p>
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Let's start from scratch. Assume you are designing a new source
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code management system. How did you do basic version control before
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you used a tool for it? Chances are that you simply copied your
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project directory to save what it looked like at that point.
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</p>
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<pre> $ cp -R project project.bak </pre>
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<p>
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That way, you can easily revert files that get messed up later, or
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see what you have changed by comparing what the project looks like
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now to what it looked like when you copied it.
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</p>
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<p>
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If you are really paranoid, you may do this often, maybe putting the
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date in the name of the backup:
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</p>
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<pre> $ cp -R project project.2010-06-01.bak </pre>
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<p>
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In that case, you may have a bunch of snapshots of your project that
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you can compare and inspect from. You can even use this model to
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fairly effectively share changes with someone. If you zip up your
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project at a known state and put it on your website, other developers
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can download that, change it and send you a patch pretty easily.
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</p>
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<pre>
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$ wget http://sample.com/project.2010-06-01.zip
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$ unzip project.2010-06-01.zip
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$ cp -R project.2010-06-01 project-my-copy
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$ cd project-my-copy
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$ (change something)
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$ diff project-my-copy project.2010-06-01 > change.patch
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$ (email change.patch)</pre>
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<p>
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Now the original developer can apply that patch to their copy of the
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project and they have your changes. This is how many open source
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projects have been collaborated on for several years.
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</p>
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<p>
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This actually works fairly well, so let's say we want to write a tool
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to make this basic process faster and easier. Instead of writing a tool
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that versions each file individually, like Subversion, we would probably
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write one that makes it easier to store snapshots of our project without
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having to copy the whole directory each time.
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</p>
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<p>
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This is essentially what Git is. You tell Git you want to save a snapshot
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of your project with the <code>git commit</code> command and it basically
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records a manifest of what all of the files in your project look like at
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that point. Then most of the commands work with those manifests to see
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how they differ or pull content out of them, etc.
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</p>
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<center><img src="./images/snapshots.png"/></center>
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<p>
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If you think about Git
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as a tool for storing and comparing and merging snapshots of your project,
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it may be easier to understand what is going on and how to do things
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properly.
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</p>
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</div>
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</div>
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<p><a href="/creating">On to Getting and Creating Projects »</a></p>
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