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archivehttps://archive-w.netlify.app/devops/os/core/fs/Recent content on archiveHugozh-CN<link>https://archive-w.netlify.app/devops/os/core/fs/ext2/</link><pubDate>Mon, 01 Jan 0001 00:00:00 +0000</pubDate><guid>https://archive-w.netlify.app/devops/os/core/fs/ext2/</guid><description><ul> <li> <h2 id="introext2-fs"> Intro(EXT2-FS) <a class="anchor" href="#introext2-fs">#</a> </h2> <p><img src="https://archive-w.netlify.app/.images/devops/os/core/fs/ext2/ext2-intro-01.png" alt="" width="100%"></p> <ul> <li> <h3 id="注意"> 注意 <a class="anchor" href="#%e6%b3%a8%e6%84%8f">#</a> </h3> <div class="alert callout attention"><p class="title"><span class="icon icon icon-attention"></span> Caution </p><p> <code>a).</code>: 上述的图例是模拟 1M 的 <strong>ext2</strong> 文件系统，采用 block = 1024B ,inode size = 128B，进行划分的。 <br><code>b).</code>: 转换成数值的时候是小端读取。比如 [80 00 00 00] ==int=> 0x00000080 = 0x80 = 128。 <br><code>c).</code>: bitmap 采用的是 (MSB)10001001(LSB)，参考 <a href="https://www.nongnu.org/ext2-doc/ext2.html#block-bitmap" rel="noopener" target="_blank">block-bitmap 中的部分描述</a>、以及 <a href="https://en.wikipedia.org/wiki/Bit_numbering" rel="noopener" target="_blank">wiki</a>，比如 10000111，指的是第1，2，3，8个，不是1，6，7，8。</p> </p></div> </li> <li> <h3 id="准备"> 准备 <a class="anchor" href="#%e5%87%86%e5%a4%87">#</a> </h3> <p class="warn">在 Ubuntu-22.04 上准备两个文件系统，一个干净的 <strong>fs1m</strong>，一个需要写入数据作对比 <strong>fs1m-with-data</strong>。 <a href="https://github.com/xhsgg12302/knownledges/blob/f72899b6dc6cfddd1c44428ecfda7e9d5d819356/.images/devops/os/core/fs/ext2/fs1m" rel="noopener" target="_blank"> fs1m 备份下载</a>、 <a href="https://github.com/xhsgg12302/knownledges/blob/f72899b6dc6cfddd1c44428ecfda7e9d5d819356/.images/devops/os/core/fs/ext2/fs1m-with-data" rel="noopener" target="_blank">fs1m-with-data 备份下载</a> <br>创建一个1M的文件：<code>dd if=/dev/zero of=fs1m count=256 bs=4K</code> <br>格式化文件系统：<code>mke2fs -b 1024 -I 128 fs1m</code> <br>查看格式化后的信息：<code>dumpe2fs fs1m</code> <br><br>复制 <strong>fs1m</strong> 到 <strong>fs1m-with-data</strong> <br>挂载：<code>mount -o loop fs1m-with-data /mnt</code> <br>进入目录并写入数据：<code>cd /mnt && mkdir 12302 && cd 12302 && echo 'something' > Hello.java</code> <br>卸载：<code>umount /mnt</code> <br><br>使用 <a href='https://archive-w.netlify.app/devops/os/util/xxd/' rel="noopener" class="internal-link" data-src="https://archive-w.netlify.app/devops/os/util/xxd/">xxd</a> 查看十六进制信息：<code>xxd -a -u -g1 -s 1024 -l 16 fs1m</code> //使用*代替连续00，大写字母输出，一个字节分割，offset=1024, len=16。</p></description></item></channel></rss>