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                    <h1 class="menu-title">Notes</h1>

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                        <h1 id="od1"><a class="header" href="#od1">od(1)</a></h1>
<pre><code class="language-markdown">  od [opts] &lt;file&gt;
    -An         don't print addr info
    -tx4        print hex in 4 byte chunks
    -ta         print as named character
    -tc         printable chars or backslash escape
    -w4         print 4 bytes per line
    -j &lt;n&gt;      skip &lt;n&gt; bytes from &lt;file&gt; (hex if start with 0x)
    -N &lt;n&gt;      dump &lt;n&gt; bytes (hex of start with 0x)
</code></pre>
<h2 id="ascii-to-hex-string"><a class="header" href="#ascii-to-hex-string">ASCII to hex string</a></h2>
<pre><code class="language-markdown">  echo -n AAAABBBB | od -An -w4 -tx4
    &gt;&gt; 41414141
    &gt;&gt; 42424242

  echo -n '\x7fELF\n' | od -tx1 -ta -tc
    &gt;&gt; 0000000  7f  45  4c  46  0a      # tx1
    &gt;&gt;         del   E   L   F  nl      # ta
    &gt;&gt;         177   E   L   F  \n      # tc
</code></pre>
<h2 id="extract-parts-of-file"><a class="header" href="#extract-parts-of-file">Extract parts of file</a></h2>
<p>For example <code>.rodata</code> section from an elf file. We can use <code>readelf</code> to get the
offset into the file where the <code>.rodata</code> section starts.</p>
<pre><code class="language-markdown">  readelf -W -S foo
    &gt;&gt; Section Headers:
    &gt;&gt; [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
    &gt;&gt; ...
    &gt;&gt; [15] .rodata           PROGBITS        00000000004009c0 0009c0 000030 00   A  0   0 16
</code></pre>
<p>With the offset of <code>-j 0x0009c0</code> we can dump <code>-N 0x30</code> bytes from the beginning of
the <code>.rodata</code> section as follows:</p>
<pre><code class="language-markdown">  od -j 0x0009c0 -N 0x30 -tx4 -w4 foo
    &gt;&gt; 0004700 00020001
    &gt;&gt; 0004704 00000000
    &gt;&gt; *
    &gt;&gt; 0004740 00000001
    &gt;&gt; 0004744 00000002
    &gt;&gt; 0004750 00000003
    &gt;&gt; 0004754 00000004
</code></pre>
<p><strong>Note</strong>: Numbers starting with <code>0x</code> will be interpreted as hex by <code>od</code>.</p>

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                        <h1 id="od1"><a class="header" href="#od1">od(1)</a></h1>
<pre><code class="language-markdown">  od [opts] &lt;file&gt;
    -An         don't print addr info
    -tx4        print hex in 4 byte chunks
    -ta         print as named character
    -tc         printable chars or backslash escape
    -w4         print 4 bytes per line
    -j &lt;n&gt;      skip &lt;n&gt; bytes from &lt;file&gt; (hex if start with 0x)
    -N &lt;n&gt;      dump &lt;n&gt; bytes (hex of start with 0x)
</code></pre>
<h2 id="ascii-to-hex-string"><a class="header" href="#ascii-to-hex-string">ASCII to hex string</a></h2>
<pre><code class="language-markdown">  echo -n AAAABBBB | od -An -w4 -tx4
    &gt;&gt; 41414141
    &gt;&gt; 42424242

  echo -n '\x7fELF\n' | od -tx1 -ta -tc
    &gt;&gt; 0000000  7f  45  4c  46  0a      # tx1
    &gt;&gt;         del   E   L   F  nl      # ta
    &gt;&gt;         177   E   L   F  \n      # tc
</code></pre>
<h2 id="extract-parts-of-file"><a class="header" href="#extract-parts-of-file">Extract parts of file</a></h2>
<p>For example <code>.rodata</code> section from an elf file. We can use <code>readelf</code> to get the
offset into the file where the <code>.rodata</code> section starts.</p>
<pre><code class="language-markdown">  readelf -W -S foo
    &gt;&gt; Section Headers:
    &gt;&gt; [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
    &gt;&gt; ...
    &gt;&gt; [15] .rodata           PROGBITS        00000000004009c0 0009c0 000030 00   A  0   0 16
</code></pre>
<p>With the offset of <code>-j 0x0009c0</code> we can dump <code>-N 0x30</code> bytes from the beginning of
the <code>.rodata</code> section as follows:</p>
<pre><code class="language-markdown">  od -j 0x0009c0 -N 0x30 -tx4 -w4 foo
    &gt;&gt; 0004700 00020001
    &gt;&gt; 0004704 00000000
    &gt;&gt; *
    &gt;&gt; 0004740 00000001
    &gt;&gt; 0004744 00000002
    &gt;&gt; 0004750 00000003
    &gt;&gt; 0004754 00000004
</code></pre>
<p><strong>Note</strong>: Numbers starting with <code>0x</code> will be interpreted as hex by <code>od</code>.</p>

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