1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
|
<!DOCTYPE HTML>
<html lang="en" class="sidebar-visible no-js ayu">
<head>
<!-- Book generated using mdBook -->
<meta charset="UTF-8">
<title>od - Notes</title>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="theme-color" content="#ffffff" />
<link rel="shortcut icon" href="favicon.png">
<link rel="stylesheet" href="css/variables.css">
<link rel="stylesheet" href="css/general.css">
<link rel="stylesheet" href="css/chrome.css">
<link rel="stylesheet" href="css/print.css" media="print">
<!-- Fonts -->
<link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
<link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css">
<link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css">
<!-- Highlight.js Stylesheets -->
<link rel="stylesheet" href="highlight.css">
<link rel="stylesheet" href="tomorrow-night.css">
<link rel="stylesheet" href="ayu-highlight.css">
<!-- Custom theme stylesheets -->
</head>
<body>
<!-- Provide site root to javascript -->
<script type="text/javascript">
var path_to_root = "";
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "ayu" : "ayu";
</script>
<!-- Work around some values being stored in localStorage wrapped in quotes -->
<script type="text/javascript">
try {
var theme = localStorage.getItem('mdbook-theme');
var sidebar = localStorage.getItem('mdbook-sidebar');
if (theme.startsWith('"') && theme.endsWith('"')) {
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
}
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
}
} catch (e) { }
</script>
<!-- Set the theme before any content is loaded, prevents flash -->
<script type="text/javascript">
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = default_theme; }
var html = document.querySelector('html');
html.classList.remove('no-js')
html.classList.remove('ayu')
html.classList.add(theme);
html.classList.add('js');
</script>
<!-- Hide / unhide sidebar before it is displayed -->
<script type="text/javascript">
var html = document.querySelector('html');
var sidebar = 'hidden';
if (document.body.clientWidth >= 1080) {
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
sidebar = sidebar || 'visible';
}
html.classList.remove('sidebar-visible');
html.classList.add("sidebar-" + sidebar);
</script>
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
<div id="sidebar-scrollbox" class="sidebar-scrollbox">
<ol class="chapter"><li class="expanded "><a href="ld.so.html"><strong aria-hidden="true">1.</strong> ld.so</a></li><li class="expanded "><a href="git.html"><strong aria-hidden="true">2.</strong> git</a></li><li class="expanded "><a href="tmux.html"><strong aria-hidden="true">3.</strong> tmux</a></li><li class="expanded "><a href="awk.html"><strong aria-hidden="true">4.</strong> awk</a></li><li class="expanded "><a href="gdb.html"><strong aria-hidden="true">5.</strong> gdb</a></li><li class="expanded "><a href="radare2.html"><strong aria-hidden="true">6.</strong> radare2</a></li><li class="expanded "><a href="emacs.html"><strong aria-hidden="true">7.</strong> emacs</a></li><li class="expanded "><a href="fish.html"><strong aria-hidden="true">8.</strong> fish</a></li><li class="expanded "><a href="strace.html"><strong aria-hidden="true">9.</strong> strace</a></li><li class="expanded "><a href="lsof.html"><strong aria-hidden="true">10.</strong> lsof</a></li><li class="expanded "><a href="pidstat.html"><strong aria-hidden="true">11.</strong> pidstat</a></li><li class="expanded "><a href="time.html"><strong aria-hidden="true">12.</strong> time</a></li><li class="expanded "><a href="pgrep.html"><strong aria-hidden="true">13.</strong> pgrep</a></li><li class="expanded "><a href="pstack.html"><strong aria-hidden="true">14.</strong> pstack</a></li><li class="expanded "><a href="pstack.html"><strong aria-hidden="true">15.</strong> pstack</a></li><li class="expanded "><a href="perf.html"><strong aria-hidden="true">16.</strong> perf</a></li><li class="expanded "><a href="oprofile.html"><strong aria-hidden="true">17.</strong> OProfile</a></li><li class="expanded "><a href="od.html" class="active"><strong aria-hidden="true">18.</strong> od</a></li><li class="expanded "><a href="xxd.html"><strong aria-hidden="true">19.</strong> xxd</a></li><li class="expanded "><a href="readelf.html"><strong aria-hidden="true">20.</strong> readelf</a></li><li class="expanded "><a href="objdump.html"><strong aria-hidden="true">21.</strong> objdump</a></li><li class="expanded "><a href="nm.html"><strong aria-hidden="true">22.</strong> nm</a></li><li class="expanded "><a href="c++filt.html"><strong aria-hidden="true">23.</strong> c++filt</a></li></ol>
</div>
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
</nav>
<div id="page-wrapper" class="page-wrapper">
<div class="page">
<div id="menu-bar" class="menu-bar">
<div id="menu-bar-sticky-container">
<div class="left-buttons">
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
<i class="fa fa-bars"></i>
</button>
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
<i class="fa fa-paint-brush"></i>
</button>
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
<li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu (default)</button></li>
</ul>
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
<i class="fa fa-search"></i>
</button>
</div>
<h1 class="menu-title">Notes</h1>
<div class="right-buttons">
<a href="print.html" title="Print this book" aria-label="Print this book">
<i id="print-button" class="fa fa-print"></i>
</a>
</div>
</div>
</div>
<div id="search-wrapper" class="hidden">
<form id="searchbar-outer" class="searchbar-outer">
<input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
</form>
<div id="searchresults-outer" class="searchresults-outer hidden">
<div id="searchresults-header" class="searchresults-header"></div>
<ul id="searchresults">
</ul>
</div>
</div>
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
<script type="text/javascript">
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
});
</script>
<div id="content" class="content">
<main>
<h1><a class="header" href="#od1" id="od1">od(1)</a></h1>
<pre><code class="language-markdown"> od [opts] <file>
-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 <n> skip <n> bytes from <file> (hex if start with 0x)
-N <n> dump <n> bytes (hex of start with 0x)
</code></pre>
<h2><a class="header" href="#ascii-to-hex-string" id="ascii-to-hex-string">ASCII to hex string</a></h2>
<pre><code class="language-markdown"> echo -n AAAABBBB | od -An -w4 -tx4
>> 41414141
>> 42424242
echo -n '\x7fELF\n' | od -tx1 -ta -tc
>> 0000000 7f 45 4c 46 0a # tx1
>> del E L F nl # ta
>> 177 E L F \n # tc
</code></pre>
<h2><a class="header" href="#extract-parts-of-file" id="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
>> Section Headers:
>> [Nr] Name Type Address Off Size ES Flg Lk Inf Al
>> ...
>> [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
>> 0004700 00020001
>> 0004704 00000000
>> *
>> 0004740 00000001
>> 0004744 00000002
>> 0004750 00000003
>> 0004754 00000004
</code></pre>
<p><strong>Note</strong>: Numbers starting with <code>0x</code> will be interpreted as hex by <code>od</code>.</p>
</main>
<nav class="nav-wrapper" aria-label="Page navigation">
<!-- Mobile navigation buttons -->
<a rel="prev" href="oprofile.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next" href="xxd.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
<div style="clear: both"></div>
</nav>
</div>
</div>
<nav class="nav-wide-wrapper" aria-label="Page navigation">
<a href="oprofile.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a href="xxd.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
</nav>
</div>
<script type="text/javascript">
window.playpen_copyable = true;
</script>
<script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
<script src="mark.min.js" type="text/javascript" charset="utf-8"></script>
<script src="searcher.js" type="text/javascript" charset="utf-8"></script>
<script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script>
<script src="highlight.js" type="text/javascript" charset="utf-8"></script>
<script src="book.js" type="text/javascript" charset="utf-8"></script>
<!-- Custom JS scripts -->
</body>
</html>
|
