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<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
<title><![CDATA[DY.Feng's Blog 叶毅锋的博客]]></title>
<link href="http://www.dyfeng.org/atom.xml" rel="self"/>
<link href="http://www.dyfeng.org/"/>
<updated>2012-09-01T10:18:53+08:00</updated>
<id>http://www.dyfeng.org/</id>
<author>
<name><![CDATA[(≧▼≦) 喵喵]]></name>
<email><![CDATA[yyfeng88625@gmail.com]]></email>
</author>
<generator uri="http://octopress.org/">Octopress</generator>
<entry>
<title type="html"><![CDATA[在Linux下做一个简单的秒表]]></title>
<link href="http://www.dyfeng.org/2012/09/01/stopwatch-in-linux/"/>
<updated>2012-09-01T10:00:00+08:00</updated>
<id>http://www.dyfeng.org/2012/09/01/stopwatch-in-linux</id>
<content type="html"><![CDATA[<p>因为要比较<code>clang</code>和<code>gcc</code>哪个编译效率更高，我把我的一个项目分别用这两种编译器编译，还比较了添加<code>-j4</code>后的编译时间。可我的<code>apt-get</code>仓库下没发现有什么好的<code>秒表</code>或者<code>计时器</code>，有的计时器是用来定时执行任务的。不过山人自有妙计，我用一行命令也做了一个秒表，Linux下没有不可能的事情。</p>
<figure class='code'><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
</pre></td><td class='code'><pre><code class=''><span class='line'>$ time read -n1</span></code></pre></td></tr></table></div></figure>
<p>结束后按回车，就能看到运行时间了，而且还精确到0.002秒哦亲。话说回来，clang比gcc没快多少，差不多的样子而已。加了<code>j4</code>，效率也没有提高4倍，加之前36秒，加之后25秒的样子，当然这个还得具体看项目的依赖关系。</p>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[关于nginx的一些配置]]></title>
<link href="http://www.dyfeng.org/2012/08/24/something-about-nginx-configuration/"/>
<updated>2012-08-24T01:10:00+08:00</updated>
<id>http://www.dyfeng.org/2012/08/24/something-about-nginx-configuration</id>
<content type="html"><![CDATA[<p>今天帮人配置了下nginx，主要是二级域名以对应文件夹为根目录。主要的问题是在<code>Windows</code>环境下配置的，而小生一直都是在<code>Linux</code>环境下工作的，对<code>Windows</code>不大了解，记录下今天学到的小技巧。</p>
<!-- more -->
<h1>使用lvh.me做域名调试</h1>
<p>因为我要配置二级域名，而我手头又没有域名，所以配置写起来很麻烦。其中一个方法是改<code>host</code>文件，可在我的XP里却死活不行，host文件改了跟没改一样，又没有开什么杀毒软件之类的，对Windows甚为不解。</p>
<p>好在有人免费提供了一些指向<code>127.0.0.1</code>的域名，<code>lvh.me</code>就是其中的一个。用他来调试nginx域名配置就最好不过了。</p>
<h1>nginx配置的</h1>
<ul>
<li>nginx的<code>IF</code>语句没有ELSE，判断语句里面没有&&和||，你别想多了，他就是一个<code>IF</code>而已。</li>
</ul>
<p>如果要用到多个逻辑判断怎么办？没有&&又没有||。我们来设置一个标记<code>$flag</code></p>
<figure class='code'><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
<span class='line-number'>9</span>
<span class='line-number'>10</span>
<span class='line-number'>11</span>
<span class='line-number'>12</span>
<span class='line-number'>13</span>
</pre></td><td class='code'><pre><code class=''><span class='line'>set $flag 'test';
</span><span class='line'>
</span><span class='line'>if ( 条件一 ){
</span><span class='line'>set $flag '';
</span><span class='line'>}
</span><span class='line'>
</span><span class='line'>if ( 条件二 ){
</span><span class='line'>set $flag '';
</span><span class='line'>}
</span><span class='line'>
</span><span class='line'>if ( $flag = 'test' ){
</span><span class='line'>做点什么;
</span><span class='line'>}</span></code></pre></td></tr></table></div></figure>
<p>等价于</p>
<figure class='code'><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
</pre></td><td class='code'><pre><code class=''><span class='line'>if ( !条件一 && !条件二 ){
</span><span class='line'>做点什么
</span><span class='line'>}</span></code></pre></td></tr></table></div></figure>
<p>所有的逻辑语句都可以用这种标记法来实现。</p>
<ul>
<li><p>文件和目录判断，linux下好像-f也能判断目录，我今天就栽在这个上了。</p>
<ul>
<li>-f和!-f判断是否存在文件</li>
<li>-d和!-d判断是否存在目录</li>
<li>-e和!-e判断是否存在文件或目录</li>
<li>-x和!-x判断文件是否可执行</li>
</ul>
</li>
<li><p>nginx配置文件的字符串比较。要注意一点，nginx的字符串都是按正则使用的。</p>
<ul>
<li>匹配
<ul>
<li>区分大小写 <code>~</code></li>
<li>不区分大小写 <code>~*</code></li>
<li>精确匹配 <code>=</code></li>
</ul>
</li>
<li>不匹配。前面加<code>!</code>
<ul>
<li>区分大小写 <code>!~</code></li>
<li>不区分大小写 <code>!~*</code></li>
<li>精确匹配 <code>!=</code></li>
</ul>
</li>
</ul>
</li>
</ul>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[解决Firefox菜单不弹出和右键失效的问题]]></title>
<link href="http://www.dyfeng.org/2012/08/23/menu-does-not-popup-and-right-click-does-not-work-in-firefox/"/>
<updated>2012-08-23T13:19:00+08:00</updated>
<id>http://www.dyfeng.org/2012/08/23/menu-does-not-popup-and-right-click-does-not-work-in-firefox</id>
<content type="html"><![CDATA[<p>最近一次kubuntu升级后，我发现一个很奇怪的现象，我的Firefox某些时候菜单栏不能弹出，右键也失灵了。准确来说，是弹出了，又很快地焦点转移，导致他又关闭了。Google下发现遇到这个问题的童鞋还真不少，而且解决的方法各有不同，看来这个问题是Firefox一直存在的。</p>
<!-- more -->
<p>网上的解决方法：</p>
<ul>
<li>升级你的Firefox到14+。</li>
<li>重装你的Firefox</li>
<li>插件冲突</li>
</ul>
<p>后来我发现他有个规律，一开始Firefox是好的，后来我在里面搜索打中文的时候，灵异的事情发生了，右键和菜单又能用了。这时候我才发现是我的输入法<code>fcitx</code>的问题。</p>
<p>解决的方法是安装<code>fcitx-frontend-gtk2</code>和<code>fcitx-frontend-gtk3</code>，因为<code>fcitx-frontend-qt4</code>我是一直有装的，所以就不重复了。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">sudo</span> apt-get install fcitx-frontend-gtk2 fcitx-frontend-gtk3
</span></code></pre></td></tr></table></div></figure>
<p>想起我这个ubuntu是先装了<code>Unity</code>界面，后来我卸载了<code>Unity</code>，重新回到我<code>KDE</code>的怀抱。可能就是在清理软件的时候，多手删了，善哉善哉。</p>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[修改octopress的pygment语法]]></title>
<link href="http://www.dyfeng.org/2012/08/18/change-the-pygment-lexer-of-octopress/"/>
<updated>2012-08-18T18:43:00+08:00</updated>
<id>http://www.dyfeng.org/2012/08/18/change-the-pygment-lexer-of-octopress</id>
<content type="html"><![CDATA[<p>最近我在写一篇关于Git使用的文章，里面贴了大量<code>bash</code>命令。我的语法高亮是用Octopress自带的<code>pygements.rb</code>，用起来总觉得不大爽，因为他高亮的地方实在是太少了，只有少量的命令有高亮。自己动手丰衣足食，下面记录我修改的过程：</p>
<!-- more -->
<h1>Octopress语法高亮原理</h1>
<p>我要修改Octopress的语法高亮，当然得搞清楚他的来龙去脉。</p>
<p>首先在<code>plugins</code>目录下你会看到<code>pygments_code.rb</code>插件，这个插件的功能就是调用<code>pygements.rb</code>库，把代码转换成html，还在你项目的<code>.pygements-cache</code>目录下缓存代码块。代码样式他其实是通过css调节的，他生成的只是一个堆html标签。</p>
<p><code>pygements.rb</code>库其实是ruby封装了python的<code>pygements</code>库，而且<code>pygements.rb</code>里面已经自带了一个<code>pygements</code>库（这真不是一个好主意，系统讲究的应该是低耦合）。</p>
<p>就这样…</p>
<ol>
<li>Octopress调用pygments_code.rb插件。</li>
<li>pygments_code.rb插件调用pygements.rb库。</li>
<li>pygements.rb库调用python的pygements库。</li>
</ol>
<p>完成了对代码的语法高亮。</p>
<h1>修改Octopress语法高亮规则</h1>
<p>你先要确保你的电脑上其他地方没有安装python的<code>pygements</code>。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">sudo</span> apt-get remove python-pygments
</span></code></pre></td></tr></table></div></figure>
<p>，我们先找出你<code>pygments.rb</code>的安装目录：</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">bundle</span> show pygments.rb
</span><span class='line'>/var/lib/gems/1.9.1/gems/pygments.rb-0.2.13
</span></code></pre></td></tr></table></div></figure>
<p>修改<code>pygements.rb</code>自带python<code>pygments</code>库的语法文件。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">cd</span> YOUR_PYGEMENTS.RB_PATH/vendor/pygments-main/
</span><span class='line'><span class="nv">$ </span><span class="nb">vim</span> pygments/lexers/shell.py
</span></code></pre></td></tr></table></div></figure>
<p>找到<code>BashLexer</code>下<code>tokens</code>字典，<code>basic</code>下，大概修改成这个样子。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
<span class='line-number'>9</span>
</pre></td><td class='code'><pre><code class='python'><span class='line'><span class="c"># (r'\b(alias|bg|bind|break|find|builtin|caller|cd|command|compgen|'</span>
</span><span class='line'><span class="c"># r'complete|declare|dirs|disown|echo|cat|enable|eval|exec|exit|'</span>
</span><span class='line'><span class="c"># r'export|false|fc|fg|getopts|hash|help|history|jobs|kill|let|'</span>
</span><span class='line'><span class="c"># r'local|logout|popd|printf|pushd|pwd|read|readonly|set|shift|'</span>
</span><span class='line'><span class="c"># r'shopt|source|suspend|test|time|times|trap|true|type|typeset|'</span>
</span><span class='line'><span class="c"># r'ulimit|umask|unalias|unset|wait'</span>
</span><span class='line'><span class="c"># r')\s*\b(?!\.)',</span>
</span><span class='line'><span class="c"># Name.Builtin),</span>
</span><span class='line'><span class="p">(</span><span class="s">r'(?<=\$\s)\b\w+'</span><span class="p">,</span><span class="n">Name</span><span class="o">.</span><span class="n">Builtin</span><span class="p">),</span>
</span></code></pre></td></tr></table></div></figure>
<p>一开始我是想遍历<code>PATH</code>下所有目录，把里面的命令都动态加上，但python的正则抗议太多选项了，所以我就唯有手动改规则了。现在的规则是以<code>$</code>开头的一个单词定义为命令。</p>
<p>最后一步千万不要漏了，清除<code>pygments_code.rb</code>插件的缓存，重新生成页面</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">rm</span> -rf .pygments-cache/*
</span><span class='line'><span class="nv">$ </span><span class="nb">rake</span> generate
</span><span class='line'><span class="nv">$ </span><span class="nb">rake</span> preview
</span></code></pre></td></tr></table></div></figure>
<p>现在你应该看到bash的语法高亮<code>亮</code>多了吧。</p>
<h1>参考文献</h1>
<ol>
<li><a href="http://pygments.org/docs/lexerdevelopment/">如何编写pygements的语法规则</a>，来自pygements官网</li>
<li><a href="http://docs.python.org/library/re.html">python正则表达式参考</a>，来自python官网</li>
</ol>
]]></content>
</entry>
<entry>
<title type="html"><![CDATA[Git深入浅出学习]]></title>
<link href="http://www.dyfeng.org/2012/08/12/all-about-git/"/>
<updated>2012-08-12T00:38:00+08:00</updated>
<id>http://www.dyfeng.org/2012/08/12/all-about-git</id>
<content type="html"><![CDATA[<p>在看这篇文章之前…</p>
<ul>
<li><p>如果你只是在找Git的使用命令，而不是想深入学习Git，请绕道。</p>
<p>Git和Linux一样，不是学几个命令就能理解到他的精髓的。</p></li>
<li><p>什么？你在Windows下？那你一定懂Cygwin了。不知道Cygwin？那你看这篇文章就有点吃力了。还不会用命令行？那你可以绕道了，这篇文章对你来说是天书。</p></li>
<li><p>请先忘记你之前所了解关于Git的一切，因为网络上的文章有99%都是以纰传纰的！！</p></li>
<li><p>请先忘记你所有学的其他版本管理系统。</p>
<p>请统统忘记<code>Svn</code>、<code>Cvs</code>、<code>Mercury</code>等，因为Git的思想跟实现跟他们有天大的区别！！</p></li>
<li><p>请不要急于求成，网上99%速成的教程都是有速度没质量的。</p>
<p>我不是说他们写的质量差，而是因为很多东西他都给简化掉了，让人有个错觉：这个很简单。其实这是不利于学习的。</p></li>
<li><p>请先从<code>最基础</code>的学起，而不是直接看操作命令，否则你只会只其然而不知其所以然，最后看到一头雾水。</p></li>
<li><p>我一开始将不会讲解任何关于使用Git的命令，而是先讲解Git的<code>底层原理</code>，如果你耐不住性子的请不要看。但我相信，这会是最快入门Git的方法之一。</p></li>
<li><p>你大概需要几天时间来消化和试验，所以不用急，慢慢看。反正你都误用了这么长时间了，花点时间来正确认识Git还是值得的。</p></li>
</ul>
<!-- 因为囊括的东西比较多，所以我这篇文章比较。对于一个作者来说，罗列知识点很容易，但你要把知识点组织起来，让人思路清晰，脉络通畅，那就是难点了。 -->
<!-- -->
<!-- 建议阅读方法： -->
<!-- -->
<!-- 0. 你可以先大概浏览一下`Local本地使用`和`Remote远程相关使用`这两章，感受一下Git的大概使用，这两章是讲述Git的在各种使用场景下的命令，不必精读。如果只是想查找命令的童鞋，看这章就可以了。 -->
<!-- 1. 再看看第一章`Git基础讲解`，最基本的概念和Git的运作方式会在这里讲述。 -->
<!-- 2. 当你遇到有不明白的术语或者词汇，不妨到`相关术语以及本文翻译`那章找找。 -->
<!-- 3. 再回来`Local本地使用`和`Remote远程相关使用`这两章。相信这个时候你应该能通过这命令，而知道他们底层究竟是做了什么操作。 -->
<!-- 4. 有空的时候可以看看`小技巧` -->
<!-- 5. 如果对Git的使用还有什么疑问，可以留言。本人也是初学Git，可以共同探讨学习。 -->
<!--more-->
<h1>Git基础讲解</h1>
<h2>Git是什么？</h2>
<p><del>Git是一个版本控制软件…</del>（地球人都知道的就不废话了，省略几百字）Git就是</p>
<ul>
<li>一个带有<code>二次元平衡世界</code>、<code>时光倒流</code>功能的<code>文件管理系统</code>。</li>
<li>一个<code>键值对</code>的数据库，<code>键</code>是<code>值</code>的SHA1值。<code>tree .git/objects</code>你就能看到他们了。</li>
<li>一个一切皆对象的系统</li>
</ul>
<!-- 为什么说他是文件管理系统呢？那跟我电脑本地的文件管理系统有什么区别？这个就得从Git的`文件模型`--基础对象模型说起了。 -->
<p>Git说白了就是一个文件储存系统，只是他储存不单单是我们普通意义上的<code>文件</code>，他还储存了<code>tree（树）</code>，<code>commit（快照）</code>，<code>tag（标签）</code>。Git能够储存的东西我们叫做<code>基础对象</code>（Git Objects）。</p>
<p>其实我们用Git做的<em>一切</em>都是围绕着这些<code>基础对象</code>而展开的，所以先学懂这个比先去学习几句命令要重要得多。</p>
<h2>Git的基本对象类型（Git Objects）</h2>
<p> 在Git系统里面有四种基本对象类型，分别是<code>blob</code>，<code>tree（树）</code>，<code>commit（快照）</code>，<code>tag（标签）</code>。几乎所有的Git都建立在管理操纵四个简单的数据结构之上，即它是建立在机器文件系统之上的一种自己的小型文件系统。</p>
<p><code>commit</code>在其他的版本控制软件很多时候都是翻译成<code>提交</code>，但在Git上他不能翻译成<code>提交</code>。他在Git上是一个<code>对象</code>，一个<code>名词</code>，一个<code>noun</code>，一个快照。这一点在很多网络文章里面都是以纰传纰的。</p>
<h3>blob对象</h3>
<p>blob对象储存了我们平常接触的文件，但他只储存了这个文件的<code>内容</code>，而没有包含修改日期、拥有者、<em>文件名</em>、目录路径之类的信息。下面我们来做个实验：</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'> <span class="nv">$ </span><span class="nb">echo</span> <span class="s1">'Hello,Git!'</span> > test.txt
</span><span class='line'> <span class="nv">$ </span><span class="nb">git</span> hash-object test.txt
</span><span class='line'> 63008ae88b4446dfc43b47f18aee5b427203b255
</span></code></pre></td></tr></table></div></figure>
<p>你可看到他生成了一个40位的<code>SHA1</code>值，这SHA1值就是通过<code>文件内容</code>计算出来的，所以说同一个文件只有一个SHA1值。如果你在你的电脑上做同样内容的一个文件，即使文件名不一样，计算出来的结果都是一样的。</p>
<p>现在我们把<code>test.txt</code>纳入我们Git的引索（index）里面：</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> add test.txt
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> commit -m <span class="s2">"add test.txt"</span> <span class="c">#这句不是必须的，git add之后就已经纳入到Git的引索里面去了</span>
</span></code></pre></td></tr></table></div></figure>
<p>提交之后，<code>test.txt</code>的内容已经放进了我们Git的blob树了，我们可以根据SHA1值来看看文件的内容：</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file blob 63008ae88b4446dfc43b47f18aee5b427203b255
</span><span class='line'>Hello,Git!
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file blob 63008a <span class="c">#其实用前六位或者七位就可以了</span>
</span><span class='line'>Hello,Git!
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file t 63008a <span class="c">#查看对象类型</span>
</span><span class='line'>blob
</span></code></pre></td></tr></table></div></figure>
<p>blob只记录文件的内容的好处：
- Git可以快速的仅仅通过对象名称决定两个对象是否相同
- 由于对象名称在每一个库（repository）中都由相同的方式计算得到，相同的内容存储到不同的库中将总被存储到相同的名称下，减少需要的硬盘空间。</p>
<h3>commit对象</h3>
<p>如果你有小用过Git，那对commit一定很熟悉，不就是提交嘛，其实不然。在这里的commit表示<code>快照</code>，是名词。跟blob一样，也是Git的<code>基础对象</code>之一。</p>
<p>查看一个快照（commit）对象，可以看到快照里记录了根目录树，作者，还有提交的信息。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file commit d5cb71
</span><span class='line'>tree e84b991fd55acf5eb290a11c0ae4149ce4ffc8dd
</span><span class='line'>author DY.Feng <yyfeng88625@gmail.com> 1345233032 +0800
</span><span class='line'>committer DY.Feng <yyfeng88625@gmail.com> 1345233032 +0800
</span><span class='line'>
</span><span class='line'>add a.txt
</span></code></pre></td></tr></table></div></figure>
<p>在下一小节<code>tree对象</code>里，我们将会学到如何创建一个快照对象，因为快照必须需要一个<code>树（tree）对象</code>。</p>
<h3>tree对象</h3>
<p>树（tree）对象跟我们本地的目录树很相似，下面我们来试验：</p>
<p>准备试验用文件</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">mkdir</span> bb <span class="o">&&</span> touch bb/a.txt <span class="c">#新建一个文件夹并放置一个空文件在里面</span>
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> add bb/a.txt <span class="o">&&</span> git commit -m <span class="s2">"add bb/a.txt"</span> <span class="c">#提交</span>
</span></code></pre></td></tr></table></div></figure>
<p>查看HEAD（这里的HEAD其实不是树对象，而是快照对象），你会看到只有两个文件，一个是<code>test.txt</code>，另外一个是<code>树bb</code>，那还有一个文件<code>a.txt</code>呢？</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> ls-tree HEAD
</span><span class='line'>040000 tree 65a457425a679cbe9adf0d2741785d3ceabb44a7 bb
</span><span class='line'>100644 blob 63008ae88b4446dfc43b47f18aee5b427203b255 test.txt
</span></code></pre></td></tr></table></div></figure>
<p>文件<code>a.txt</code>在<code>bb树</code>里面。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$git</span> ls-tree 65a457425a679cbe9adf0d2741785d3ceabb44a7
</span><span class='line'>100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 a.txt
</span></code></pre></td></tr></table></div></figure>
<p>树也是Git的<code>基本对象</code>，所以准确来说：blob对象<em>不是</em>储存在树对象里面，而是树对象里面写有blob对象的<code>SHA1值</code>，所以tree对象可以查找到blob对象。</p>
<p>不知道你看到这里有没有发现，我们上面的树（tree）对象，我们并没有手动添加，在<code>git add</code>的时候也没有新增，而是在<code>git commit</code>之后增加的。究竟树对象是怎么新建的呢？下面我们来试验手动添加树对象：</p>
<p>重置我们的工作目录。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">rm</span> -rf * .git/
</span><span class='line'><span class="nv">$ </span><span class="nb">echo</span> <span class="s1">'Good bye'</span> > a.txt
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> init
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> add a.txt
</span></code></pre></td></tr></table></div></figure>
<p>现在引索（stage）里有我们的a.txt了。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> ls-files --stage
</span><span class='line'>100644 c0ee9ab00ab41be0d401f00f7a4aaf2e478f9f1e 0 a.txt
</span><span class='line'><span class="nv">$ </span><span class="nb">find</span> .git/objects -type f | sort
</span><span class='line'>.git/objects/c0/ee9ab00ab41be0d401f00f7a4aaf2e478f9f1e
</span></code></pre></td></tr></table></div></figure>
<p>我们来创造一棵树吧，在你的电脑上应该会得到同样的一串SHA1值，因为这棵树里面的文件（文件名和文件SHA1值）我们是一样的。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'>git write-tree
</span><span class='line'>e84b991fd55acf5eb290a11c0ae4149ce4ffc8dd
</span></code></pre></td></tr></table></div></figure>
<p>有了一棵树，我们就能创造出一个快照（commit）了。记得前面说过，一个快照（commit）里面包含了一个树对象的SHA1值，所以你如果要创造一个快照（commit），就必须有一棵树。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">echo</span> <span class="s2">"add a.txt"</span> |git commit-tree e84b99 <span class="c">#新建一个快照，并把树e84b99添加到里面</span>
</span><span class='line'>d5cb71ea0e9c6a2c6b198bd5e44b80bd72aac806
</span><span class='line'><span class="nv">$ </span><span class="nb">find</span> .git/objects -type f | sort <span class="c">#我们现在有了一个文件，一棵树，还有一个快照</span>
</span><span class='line'>.git/objects/c0/ee9ab00ab41be0d401f00f7a4aaf2e478f9f1e
</span><span class='line'>.git/objects/d5/cb71ea0e9c6a2c6b198bd5e44b80bd72aac806
</span><span class='line'>.git/objects/e8/4b991fd55acf5eb290a11c0ae4149ce4ffc8dd
</span></code></pre></td></tr></table></div></figure>
<p>如果这个快照是有parent的，也就是说在这个快照之前，已经创建过一个快照，他们在同一条分支（branch）上。那你可以指定<code>-p 选项</code>来指定parent。</p>
<p>我们把<code>master分支头（the head of master branch）</code>指向到<code>目前的快照（current commit）</code>。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">echo</span> d5cb71ea0e9c6a2c6b198bd5e44b80bd72aac806 > .git/refs/heads/master
</span></code></pre></td></tr></table></div></figure>
<p>或者用更加安全的方法。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> update-ref ref/heads/master d5cb71
</span></code></pre></td></tr></table></div></figure>
<p>我们再把<code>HEAD</code>指向到master分支头（这一步在我的电脑上，<code>git init</code>的时候他已经帮我完成了）。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> symbolic-ref HEAD refs/heads/master
</span></code></pre></td></tr></table></div></figure>
<p>到目前为止，我们已经成功手动完成了一次<code>git commit</code>。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> log
</span><span class='line'>commit d5cb71ea0e9c6a2c6b198bd5e44b80bd72aac806
</span><span class='line'>Author: DY.Feng <yyfeng88625@gmail.com>
</span><span class='line'>Date: Sat Aug 18 03:50:32 2012 +0800
</span><span class='line'>
</span><span class='line'> add a.txt
</span></code></pre></td></tr></table></div></figure>
<p>如果我们没有把master分支头指向到<code>目前的快照</code>，或者快照沒有成为别人的parent，简单一句就是<code>孤立的快照</code>，不能被正常访问到的。那么他就有可能被Git的垃圾回收程序（<code>git gc</code>，他不仅回收垃圾，貌似还会压缩）删除。</p>
<h3>tag对象</h3>
<p>标签（tag）跟我们平时的标签贴纸用途非常相似，你可以把一个标签贴到一个对象上（例如commit对象，甚至是tag对象），用来标记这个对象的用途。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
<span class='line-number'>9</span>
<span class='line-number'>10</span>
<span class='line-number'>11</span>
<span class='line-number'>12</span>
<span class='line-number'>13</span>
<span class='line-number'>14</span>
<span class='line-number'>15</span>
<span class='line-number'>16</span>
<span class='line-number'>17</span>
<span class='line-number'>18</span>
<span class='line-number'>19</span>
<span class='line-number'>20</span>
<span class='line-number'>21</span>
<span class='line-number'>22</span>
<span class='line-number'>23</span>
<span class='line-number'>24</span>
<span class='line-number'>25</span>
<span class='line-number'>26</span>
<span class='line-number'>27</span>
<span class='line-number'>28</span>
<span class='line-number'>29</span>
<span class='line-number'>30</span>
<span class='line-number'>31</span>
<span class='line-number'>32</span>
<span class='line-number'>33</span>
<span class='line-number'>34</span>
<span class='line-number'>35</span>
<span class='line-number'>36</span>
<span class='line-number'>37</span>
<span class='line-number'>38</span>
<span class='line-number'>39</span>
<span class='line-number'>40</span>
<span class='line-number'>41</span>
<span class='line-number'>42</span>
<span class='line-number'>43</span>
<span class='line-number'>44</span>
<span class='line-number'>45</span>
<span class='line-number'>46</span>
<span class='line-number'>47</span>
<span class='line-number'>48</span>
<span class='line-number'>49</span>
<span class='line-number'>50</span>
<span class='line-number'>51</span>
<span class='line-number'>52</span>
<span class='line-number'>53</span>
<span class='line-number'>54</span>
<span class='line-number'>55</span>
<span class='line-number'>56</span>
<span class='line-number'>57</span>
<span class='line-number'>58</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">rm</span> -rf .git <span class="c">#我们把现有的.git删除，重新建立一个干净的git</span>
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> init
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> add test.txt
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> ls-files --stage
</span><span class='line'>100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0 test.txt
</span><span class='line'>
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> tag <span class="s1">'my_file_test.txt'</span> e69de29 <span class="c">#给文件test.txt打个标签，标签名称不能有空格</span>
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> tag
</span><span class='line'>my_file_test.txt
</span><span class='line'><span class="nv">$ </span><span class="nb">cat</span> .git/refs/tags/my_file_test.txt <span class="c">#可以看到.git/refs/tags/目录下储存了一个标签，标签内容就是文件的SHA1值</span>
</span><span class='line'>e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
</span><span class='line'><span class="nv">$ </span><span class="nb">find</span> .git/objects -type f |sort <span class="c">#这个时候tag没有储存到objects目录下，也就是说他现在不是对象</span>
</span><span class='line'>.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
</span><span class='line'>
</span><span class='line'>
</span><span class='line'><span class="c">#我们再新建一个文件</span>
</span><span class='line'><span class="nv">$ </span><span class="nb">echo</span> <span class="s2">"Today,I have many many homework"</span> > homework.txt
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> add homework.txt
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> ls-files --stage
</span><span class='line'>100644 36821547a08783ec0779dfa89d9f714196402dc6 0 homework.txt
</span><span class='line'>100644 e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 0 test.txt
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> tag -m <span class="s2">"This is my homework"</span> v1.0 3682154 <span class="c">#homework.txt贴上标签，这次加上标签描述</span>
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> tag
</span><span class='line'>my_file_test.txt
</span><span class='line'>v1.0
</span><span class='line'><span class="nv">$ </span><span class="nb">cat</span> .git/refs/tags/v1.0 <span class="c">#这次看到他指向的并不是homework.txt文件</span>
</span><span class='line'>d1e1a5c0a8c01ac604c87e51d583131d7f9a3ebf
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file -t d1e1a5c <span class="c">#原来这次指向的是一个标签（tag）</span>
</span><span class='line'>tag
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file tag d1e1a5c <span class="c">#让我们来看看标签里面究竟装了什么</span>
</span><span class='line'>object 36821547a08783ec0779dfa89d9f714196402dc6
</span><span class='line'>type blob
</span><span class='line'>tag v1.0
</span><span class='line'>tagger DY.Feng <yyfeng88625@gmail.com> 1345259919 +0800
</span><span class='line'>
</span><span class='line'>This is my homework
</span><span class='line'><span class="nv">$ </span><span class="nb">find</span> .git/objects -type f |sort <span class="c">#这里可以看到这时候的标签（tag）是一个对象了</span>
</span><span class='line'>.git/objects/36/821547a08783ec0779dfa89d9f714196402dc6
</span><span class='line'>.git/objects/d1/e1a5c0a8c01ac604c87e51d583131d7f9a3ebf
</span><span class='line'>.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
</span><span class='line'>
</span><span class='line'><span class="c">#从上面的试验可以看到，tag不一定是基本对象。</span>
</span><span class='line'>
</span><span class='line'><span class="c">#tag也可以贴到tag对象上</span>
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> tag -m <span class="s2">"This is the tag of tag"</span> v2.0 d1e1a5
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> tag
</span><span class='line'>my_file_test.txt
</span><span class='line'>v1.0
</span><span class='line'>v2.0
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file -t v2.0
</span><span class='line'>tag
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file tag v2.0 <span class="c">#不一定要用SHA1值，用引用就可以了。</span>
</span><span class='line'>object d1e1a5c0a8c01ac604c87e51d583131d7f9a3ebf
</span><span class='line'>type tag
</span><span class='line'>tag v2.0
</span><span class='line'>tagger DY.Feng <yyfeng88625@gmail.com> 1345260572 +0800
</span><span class='line'>
</span><span class='line'>This is the tag of tag
</span></code></pre></td></tr></table></div></figure>
<h3>总结</h3>
<p>究竟我们上面的所有动作，Git都是怎么储存的？让我们看看他都储存了什么文件吧：</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
<span class='line-number'>9</span>
<span class='line-number'>10</span>
<span class='line-number'>11</span>
<span class='line-number'>12</span>
<span class='line-number'>13</span>
<span class='line-number'>14</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">rm</span> -rf .git <span class="c">#我们把现有的.git删除，重新建立一个干净的git</span>
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> init
</span><span class='line'><span class="nv">$ </span><span class="nb">tree</span> .
</span><span class='line'>.
</span><span class='line'>├── bb
</span><span class='line'>│ └── a.txt
</span><span class='line'>└── test.txt
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> commit -m <span class="s2">"add all"</span> -a <span class="c">#添加并提交所有的文件到git</span>
</span><span class='line'><span class="nv">$ </span><span class="nb">find</span> .git/objects -type f | sort
</span><span class='line'>.git/objects/45/893175c9b60bdd4727c2a51ced8bae8a9c213f
</span><span class='line'>.git/objects/5b/e1b8923c561189f1fcfc5bcf2d2fe0b7684e76
</span><span class='line'>.git/objects/63/008ae88b4446dfc43b47f18aee5b427203b255
</span><span class='line'>.git/objects/65/a457425a679cbe9adf0d2741785d3ceabb44a7
</span><span class='line'>.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
</span></code></pre></td></tr></table></div></figure>
<p>从上面我们可以看到，现在有两个文件，两个目录（根目录和bb目录），一个快照（commit）。</p>
<p>这个就是我们的快照（commit），可以看到快照里记录了根目录树。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file -t 45893175c9b60bdd4727c2a51ced8bae8a9c213f
</span><span class='line'>commit
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file commit 45893175c9b60bdd4727c2a51ced8bae8a9c213f
</span><span class='line'>tree 5be1b8923c561189f1fcfc5bcf2d2fe0b7684e76
</span><span class='line'>author DY.Feng <yyfeng88625@gmail.com> 1345226467 +0800
</span><span class='line'>committer DY.Feng <yyfeng88625@gmail.com> 1345226467 +0800
</span><span class='line'>
</span><span class='line'>add all
</span></code></pre></td></tr></table></div></figure>
<p>查看根目录树，可以看到他里面包含了<code>test.txt文件</code>和<code>bb目录</code>的SHA1值，就像一个指针一样指向他们。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file -t 5be1b8923c561189f1fcfc5bcf2d2fe0b7684e76
</span><span class='line'>tree
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> ls-tree 5be1b8923c561189f1fcfc5bcf2d2fe0b7684e76
</span><span class='line'>040000 tree 65a457425a679cbe9adf0d2741785d3ceabb44a7 bb
</span><span class='line'>100644 blob 63008ae88b4446dfc43b47f18aee5b427203b255 test.txt
</span></code></pre></td></tr></table></div></figure>
<p>查看<code>test.txt</code></p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file -t 63008ae88b4446dfc43b47f18aee5b427203b255
</span><span class='line'>blob
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file blob 63008ae88b4446dfc43b47f18aee5b427203b255
</span><span class='line'>Hello,Git!
</span></code></pre></td></tr></table></div></figure>
<p>这个是<code>bb目录</code>树，里面只有一个文件<code>a.txt</code>。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file -t 65a457425a679cbe9adf0d2741785d3ceabb44a7
</span><span class='line'>tree
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> ls-tree 65a457425a679cbe9adf0d2741785d3ceabb44a7
</span><span class='line'>100644 blob e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 a.txt
</span></code></pre></td></tr></table></div></figure>
<p>这个是<code>bb目录</code>里面的<code>a.txt</code>。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> cat-file -t e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
</span><span class='line'>blob
</span></code></pre></td></tr></table></div></figure>
<p>一共增加了5个文件。</p>
<p>这个时候我们改改<code>bb/a.txt</code>文件。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">echo</span> <span class="s1">'Good'</span> >bb/a.txt
</span></code></pre></td></tr></table></div></figure>
<p>让Git跟踪<code>bb/a.txt</code>文件。你会看到里面会新增了一个文件，他就是新修改的<code>bb/a.txt</code>文件。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> add .
</span><span class='line'><span class="nv">$ </span><span class="nb">find</span> .git/objects -type f | sort
</span><span class='line'>.git/objects/45/893175c9b60bdd4727c2a51ced8bae8a9c213f
</span><span class='line'>.git/objects/5b/e1b8923c561189f1fcfc5bcf2d2fe0b7684e76
</span><span class='line'>.git/objects/63/008ae88b4446dfc43b47f18aee5b427203b255
</span><span class='line'>.git/objects/65/a457425a679cbe9adf0d2741785d3ceabb44a7
</span><span class='line'>.git/objects/cd/9dd73b78cf79e797c97b8fd5d8b92e28d4437f
</span><span class='line'>.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
</span></code></pre></td></tr></table></div></figure>
<p>即使我们现在用<code>git checkout</code>和<code>git reset</code>，新增加的那个文件也不会消失，虽然我们现在无法通过正常的途径来获取他。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
<span class='line-number'>4</span>
<span class='line-number'>5</span>
<span class='line-number'>6</span>
<span class='line-number'>7</span>
<span class='line-number'>8</span>
<span class='line-number'>9</span>
<span class='line-number'>10</span>
<span class='line-number'>11</span>
<span class='line-number'>12</span>
<span class='line-number'>13</span>
<span class='line-number'>14</span>
<span class='line-number'>15</span>
<span class='line-number'>16</span>
<span class='line-number'>17</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> checkout HEAD
</span><span class='line'>M bb/a.txt <span class="nv">$ </span><span class="nb">find</span> .git/objects -type f | sort
</span><span class='line'>.git/objects/45/893175c9b60bdd4727c2a51ced8bae8a9c213f
</span><span class='line'>.git/objects/5b/e1b8923c561189f1fcfc5bcf2d2fe0b7684e76
</span><span class='line'>.git/objects/63/008ae88b4446dfc43b47f18aee5b427203b255
</span><span class='line'>.git/objects/65/a457425a679cbe9adf0d2741785d3ceabb44a7
</span><span class='line'>.git/objects/cd/9dd73b78cf79e797c97b8fd5d8b92e28d4437f
</span><span class='line'>.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
</span><span class='line'><span class="nv">$ </span><span class="nb">git</span> reset --hard HEAD
</span><span class='line'>HEAD is now at 4589317 add all
</span><span class='line'><span class="nv">$ </span><span class="nb">find</span> .git/objects -type f | sort
</span><span class='line'>.git/objects/45/893175c9b60bdd4727c2a51ced8bae8a9c213f
</span><span class='line'>.git/objects/5b/e1b8923c561189f1fcfc5bcf2d2fe0b7684e76
</span><span class='line'>.git/objects/63/008ae88b4446dfc43b47f18aee5b427203b255
</span><span class='line'>.git/objects/65/a457425a679cbe9adf0d2741785d3ceabb44a7
</span><span class='line'>.git/objects/cd/9dd73b78cf79e797c97b8fd5d8b92e28d4437f
</span><span class='line'>.git/objects/e6/9de29bb2d1d6434b8b29ae775ad8c2e48c5391
</span></code></pre></td></tr></table></div></figure>
<p>从这里我们就可以看出Git与其他的版本管理系统有什么区别。最大的区别就是Git记录的其实是每个文件的快照，但他不管这个快照是什么时候在什么目录被什么人建立的，因为这些他都可以通过<code>tree对象</code>和<code>commit对象</code>来推算出来。</p>
<h2>引用（ref）</h2>
<p>其实上面我们已经看过了很多个引用，或者叫指向。像HEAD，master，tag这些都是引用。所有的引用都放在<code>.git/refs/</code>里。通过引用，我们可以很方便地调用Git的基本对象。</p>
<h2>关于分支（branch）</h2>
<p>在Git系统里面，分支（branch）並不是基本类型，而是某个<code>快照（commit）</code>的引用。这个非常容易理解，要知道，我们的<code>快照（commit）</code>是一个链式结构，从最新的那个快照起，我们可以完整地追溯到他的所有父快照。</p>
<h1>Local本地使用</h1>
<p>这章的题目叫<code>Local本地</code>，是因为这一章的操作你都不需要连接互联网就能完成。这也是分布式版本管理的一个特点，每个人都是一个<code>完整</code>的版本（相对自己而言），你可以在你的本机上检出，提交，删除…</p>
<h2>初始化</h2>
<h3>设置全局变量</h3>
<p>名字和Email会作为Github显示的依据。你不设置，没问题，只是Github的提交里显示不出你的用户名而已。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
<span class='line-number'>2</span>
<span class='line-number'>3</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'>git config --global user.name <span class="s2">"DY.Feng"</span>
</span><span class='line'>git config --global user.email <span class="s2">"yyfeng88625"</span>
</span><span class='line'>git config --global color.ui <span class="s2">"always"</span>
</span></code></pre></td></tr></table></div></figure>
<h3>初始化新版本库</h3>
<p>初始化，只会在根目录下创建一个<code>.git</code>的文件夹。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'>git init
</span></code></pre></td></tr></table></div></figure>
<p>初始化后的目录结构</p>
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<span class='line-number'>23</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">tree</span> .git/
</span><span class='line'>.git/
</span><span class='line'>├── branches
</span><span class='line'>├── config
</span><span class='line'>├── description
</span><span class='line'>├── HEAD
</span><span class='line'>├── hooks
</span><span class='line'>│ ├── applypatch-msg.sample
</span><span class='line'>│ ├── commit-msg.sample
</span><span class='line'>│ ├── post-update.sample
</span><span class='line'>│ ├── pre-applypatch.sample
</span><span class='line'>│ ├── pre-commit.sample
</span><span class='line'>│ ├── prepare-commit-msg.sample
</span><span class='line'>│ ├── pre-rebase.sample
</span><span class='line'>│ └── update.sample
</span><span class='line'>├── info
</span><span class='line'>│ └── exclude
</span><span class='line'>├── objects
</span><span class='line'>│ ├── info
</span><span class='line'>│ └── pack
</span><span class='line'>└── refs
</span><span class='line'> ├── heads
</span><span class='line'> └── tags
</span></code></pre></td></tr></table></div></figure>
<h3>设置忽略文件</h3>
<ul>
<li>新建<code>.gitignore</code>文件并提交。</li>
<li>修改<code>.git/info/exclude</code>文件，支持正则表达式，例如<code>*.[oa]</code>等价于 <code>*.o</code> 和 <code>*.a</code>。这个方法只适用于你个人。</li>
</ul>
<h2>日常操作</h2>
<h3>添加文件到缓存区</h3>
<ul>
<li>添加个别文件。<code>git add somefile1 somefile2</code></li>
<li>添加本目录所有txt文件。<code>git add *.txt</code></li>
<li><code>递归</code>添加所有文件，不包括空目录。<code>git add .</code></li>
</ul>
<h3>从缓存区删除文件</h3>
<p>用法跟rm一样，<code>git rm --cached</code>。</p>
<ul>
<li>删除单个文件。<code>git rm --cached somefile</code></li>
<li>递归删除。<code>git rm --cached -r .</code></li>
</ul>
<h3>查看当前缓存区的情况</h3>
<p>当前缓存区的情况是<code>注释</code>掉的，这也正常嘛，还没正式提交。<code>git status</code>是查看当前缓存区（index）和HEAD之间的差异。</p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> status
</span></code></pre></td></tr></table></div></figure>
<p>例如下面的例子就是说明:当前缓存区比HEAD要多一个文件<code>c.txt</code></p>
<figure class='code'><figcaption><span></span></figcaption><div class="highlight"><table><tr><td class="gutter"><pre class="line-numbers"><span class='line-number'>1</span>
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</pre></td><td class='code'><pre><code class='bash'><span class='line'><span class="nv">$ </span><span class="nb">git</span> status
</span><span class='line'><span class="c"># On branch master</span>
</span><span class='line'><span class="c"># Changes to be committed:</span>
</span><span class='line'><span class="c"># (use "git reset HEAD <file>..." to unstage)</span>
</span><span class='line'><span class="c">#</span>
</span><span class='line'><span class="c"># new file: c.txt</span>
</span><span class='line'><span class="c">#</span>
</span></code></pre></td></tr></table></div></figure>
<h3>从HEAD签出文件</h3>