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23 <script language="JavaScript" src="../jscript/codes.js"></script><basefont size="3">
24 <center><font size="2">The Open Group Base Specifications Issue 8<br>
25 IEEE Std 1003.1-2024<br>
26 Copyright © 2001-2024 The IEEE and The Open Group</font></center>
27 <hr size="2" noshade>
28 <a name="top" id="top"></a> <a name="od" id="od"></a> <a name="tag_20_90" id="tag_20_90"></a><!-- od -->
29 <h4 class="mansect"><a name="tag_20_90_01" id="tag_20_90_01"></a>NAME</h4>
30 <blockquote>od — dump files in various formats</blockquote>
31 <h4 class="mansect"><a name="tag_20_90_02" id="tag_20_90_02"></a>SYNOPSIS</h4>
32 <blockquote class="synopsis">
33 <p><code><tt>od</tt> <b>[</b><tt>-v</tt><b>] [</b><tt>-A</tt> <i>address_base</i><b>] [</b><tt>-j</tt> <i>skip</i><b>] [</b><tt>-N</tt>
34 <i>count</i><b>] [</b><tt>-t</tt> <i>type_string</i><b>]</b><tt>...<br>
35 </tt> <b>[</b><i>file</i><tt>...</tt><b>]</b> <tt><br>
36 <br></tt></code></p>
37 <div class="box"><code><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt=
38 "[Option Start]" border="0"> od</tt> <b>[</b><tt>-bcdosx</tt><b>] [</b><i>file</i><b>]
39 [[</b><tt>+</tt><b>]</b><i>offset</i><b>[</b><tt>.</tt><b>][</b><tt>b</tt><b>]]</b> <tt><img src="../images/opt-end.gif" alt=
40 "[Option End]" border="0"></tt></code></div>
41 <tt><br></tt></blockquote>
42 <h4 class="mansect"><a name="tag_20_90_03" id="tag_20_90_03"></a>DESCRIPTION</h4>
43 <blockquote>
44 <p>The <i>od</i> utility shall write the contents of its input files to standard output in a user-specified format.</p>
45 </blockquote>
46 <h4 class="mansect"><a name="tag_20_90_04" id="tag_20_90_04"></a>OPTIONS</h4>
47 <blockquote>
48 <p>The <i>od</i> utility shall conform to XBD <a href="../basedefs/V1_chap12.html#tag_12_02"><i>12.2 Utility Syntax
49 Guidelines</i></a> , except that the order of presentation of the <b>-t</b> options <sup>[<a href=
50 "javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> and the
51 <b>-bcdosx</b> options <img src="../images/opt-end.gif" alt="[Option End]" border="0"> is significant.</p>
52 <p>The following options shall be supported:</p>
53 <dl compact>
54 <dd></dd>
55 <dt><b>-A </b><i>address_base</i></dt>
56 <dd><br>
57 Specify the input offset base. See the EXTENDED DESCRIPTION section. The application shall ensure that the <i>address_base</i>
58 option-argument is a character. The characters <tt>'d'</tt>, <tt>'o'</tt>, and <tt>'x'</tt> specify that the offset base shall be
59 written in decimal, octal, or hexadecimal, respectively. The character <tt>'n'</tt> specifies that the offset shall not be
60 written.</dd>
61 <dt><b>-b</b></dt>
62 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
63 Interpret bytes in octal. This shall be equivalent to <b>-t o1</b>. <img src="../images/opt-end.gif" alt="[Option End]"
64 border="0"></dd>
65 <dt><b>-c</b></dt>
66 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
67 Interpret bytes as characters specified by the current setting of the <i>LC_CTYPE</i> category. Certain non-graphic characters
68 appear as C escapes: <tt>"NUL=\0"</tt>, <tt>"BS=\b"</tt>, <tt>"FF=\f"</tt>, <tt>"NL=\n"</tt>, <tt>"CR=\r"</tt>, <tt>"HT=\t"</tt>;
69 others appear as 3-digit octal numbers. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
70 <dt><b>-d</b></dt>
71 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
72 Interpret <i>word</i>s (two-byte units) in unsigned decimal. This shall be equivalent to <b>-t u2</b>. <img src=
73 "../images/opt-end.gif" alt="[Option End]" border="0"></dd>
74 <dt><b>-j </b><i>skip</i></dt>
75 <dd>Jump over <i>skip</i> bytes from the beginning of the input. The <i>od</i> utility shall read or seek past the first
76 <i>skip</i> bytes in the concatenated input files. If the combined input is not at least <i>skip</i> bytes long, the <i>od</i>
77 utility shall write a diagnostic message to standard error and exit with a non-zero exit status.
78 <p>By default, the <i>skip</i> option-argument shall be interpreted as a decimal number. With a leading 0x or 0X, the offset shall
79 be interpreted as a hexadecimal number; otherwise, with a leading <tt>'0'</tt>, the offset shall be interpreted as an octal number.
80 Appending the character <tt>'b'</tt>, <tt>'k'</tt>, or <tt>'m'</tt> to offset shall cause it to be interpreted as a multiple of
81 512, 1024, or 1048576 bytes, respectively. If the <i>skip</i> number is hexadecimal, any appended <tt>'b'</tt> shall be considered
82 to be the final hexadecimal digit.</p>
83 </dd>
84 <dt><b>-N </b><i>count</i></dt>
85 <dd>Format no more than <i>count</i> bytes of input. By default, <i>count</i> shall be interpreted as a decimal number. With a
86 leading 0x or 0X, <i>count</i> shall be interpreted as a hexadecimal number; otherwise, with a leading <tt>'0'</tt>, it shall be
87 interpreted as an octal number. If <i>count</i> bytes of input (after successfully skipping, if <b>-j</b> <i>skip</i> is specified)
88 are not available, it shall not be considered an error; the <i>od</i> utility shall format the input that is available.</dd>
89 <dt><b>-o</b></dt>
90 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
91 Interpret <i>word</i>s (two-byte units) in octal. This shall be equivalent to <b>-t o2</b>. <img src="../images/opt-end.gif"
92 alt="[Option End]" border="0"></dd>
93 <dt><b>-s</b></dt>
94 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
95 Interpret <i>word</i>s (two-byte units) in signed decimal. This shall be equivalent to <b>-t d2</b>. <img src=
96 "../images/opt-end.gif" alt="[Option End]" border="0"></dd>
97 <dt><b>-t </b><i>type_string</i></dt>
98 <dd><br>
99 Specify one or more output types. See the EXTENDED DESCRIPTION section. The application shall ensure that the <i>type_string</i>
100 option-argument is a string specifying the types to be used when writing the input data. The string shall consist of the type
101 specification characters <tt>a</tt>, <tt>c</tt>, <tt>d</tt>, <tt>f</tt>, <tt>o</tt>, <tt>u</tt>, and <tt>x</tt>, specifying named
102 character, character, signed decimal, floating point, octal, unsigned decimal, and hexadecimal, respectively. The type
103 specification characters <tt>d</tt>, <tt>f</tt>, <tt>o</tt>, <tt>u</tt>, and <tt>x</tt> can be followed by an optional unsigned
104 decimal integer that specifies the number of bytes to be transformed by each instance of the output type. The type specification
105 character <tt>f</tt> can be followed by an optional <tt>F</tt>, <tt>D</tt>, or <tt>L</tt> indicating that the conversion should be
106 applied to an item of type <b>float</b>, <b>double</b>, or <b>long double</b>, respectively. The type specification characters
107 <tt>d</tt>, <tt>o</tt>, <tt>u</tt>, and <tt>x</tt> can be followed by an optional <tt>C</tt>, <tt>S</tt>, <tt>I</tt>, or <tt>L</tt>
108 indicating that the conversion should be applied to an item of type <b>char</b>, <b>short</b>, <b>int</b>, or <b>long</b>,
109 respectively. Multiple types can be concatenated within the same <i>type_string</i> and multiple <b>-t</b> options can be
110 specified. Output lines shall be written for each type specified in the order in which the type specification characters are
111 specified.</dd>
112 <dt><b>-v</b></dt>
113 <dd>Write all input data. Without the <b>-v</b> option, any number of groups of output lines, which would be identical to the
114 immediately preceding group of output lines (except for the byte offsets), shall be replaced with a line containing only an
115 <asterisk> (<tt>'*'</tt>).</dd>
116 <dt><b>-x</b></dt>
117 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
118 Interpret <i>word</i>s (two-byte units) in hexadecimal. This shall be equivalent to <b>-t x2</b>. <img src=
119 "../images/opt-end.gif" alt="[Option End]" border="0"></dd>
120 </dl>
121 <p><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
122 Multiple types can be specified by using multiple <b>-bcdostx</b> options. Output lines are written for each type specified in the
123 order in which the types are specified. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p>
124 </blockquote>
125 <h4 class="mansect"><a name="tag_20_90_05" id="tag_20_90_05"></a>OPERANDS</h4>
126 <blockquote>
127 <p>The following operands shall be supported:</p>
128 <dl compact>
129 <dd></dd>
130 <dt><i>file</i></dt>
131 <dd>A pathname of a file to be read. If no <i>file</i> operands are specified, the standard input shall be used.
132 <p>If there are no more than two operands, none of the <b>-A</b>, <b>-j</b>, <b>-N</b>, <b>-t</b>, or <b>-v</b> options is
133 specified, and either of the following is true: the first character of the last operand is a <plus-sign> (<tt>'+'</tt>), or
134 there are two operands and the first character of the last operand is numeric; <sup>[<a href=
135 "javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> the last
136 operand shall be interpreted as an offset operand on XSI-conformant systems. <img src="../images/opt-end.gif" alt="[Option End]"
137 border="0"> Under these conditions, the results are unspecified on systems that are not XSI-conformant systems.</p>
138 </dd>
139 <dt><b>[+]</b><i>offset</i><b>[.][b]</b></dt>
140 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
141 The <i>offset</i> operand specifies the offset in the file where dumping is to commence. This operand is normally interpreted as
142 octal bytes. If <tt>'.'</tt> is appended, the offset shall be interpreted in decimal. If <tt>'b'</tt> is appended, the offset shall
143 be interpreted in units of 512 bytes. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
144 </dl>
145 </blockquote>
146 <h4 class="mansect"><a name="tag_20_90_06" id="tag_20_90_06"></a>STDIN</h4>
147 <blockquote>
148 <p>The standard input shall be used if no <i>file</i> operands are specified, and shall be used if a <i>file</i> operand is
149 <tt>'-'</tt> and the implementation treats the <tt>'-'</tt> as meaning standard input. Otherwise, the standard input shall not be
150 used. See the INPUT FILES section.</p>
151 </blockquote>
152 <h4 class="mansect"><a name="tag_20_90_07" id="tag_20_90_07"></a>INPUT FILES</h4>
153 <blockquote>
154 <p>The input files can be any file type.</p>
155 </blockquote>
156 <h4 class="mansect"><a name="tag_20_90_08" id="tag_20_90_08"></a>ENVIRONMENT VARIABLES</h4>
157 <blockquote>
158 <p>The following environment variables shall affect the execution of <i>od</i>:</p>
159 <dl compact>
160 <dd></dd>
161 <dt><i>LANG</i></dt>
162 <dd>Provide a default value for the internationalization variables that are unset or null. (See XBD <a href=
163 "../basedefs/V1_chap08.html#tag_08_02"><i>8.2 Internationalization Variables</i></a> for the precedence of internationalization
164 variables used to determine the values of locale categories.)</dd>
165 <dt><i>LC_ALL</i></dt>
166 <dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd>
167 <dt><i>LC_CTYPE</i></dt>
168 <dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as
169 opposed to multi-byte characters in arguments and input files).</dd>
170 <dt><i>LC_MESSAGES</i></dt>
171 <dd><br>
172 Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.</dd>
173 <dt><i>LC_NUMERIC</i></dt>
174 <dd><br>
175 Determine the locale for selecting the radix character used when writing floating-point formatted output.</dd>
176 <dt><i>NLSPATH</i></dt>
177 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
178 Determine the location of messages objects and message catalogs. <img src="../images/opt-end.gif" alt="[Option End]" border=
179 "0"></dd>
180 </dl>
181 </blockquote>
182 <h4 class="mansect"><a name="tag_20_90_09" id="tag_20_90_09"></a>ASYNCHRONOUS EVENTS</h4>
183 <blockquote>
184 <p>Default.</p>
185 </blockquote>
186 <h4 class="mansect"><a name="tag_20_90_10" id="tag_20_90_10"></a>STDOUT</h4>
187 <blockquote>
188 <p>See the EXTENDED DESCRIPTION section.</p>
189 </blockquote>
190 <h4 class="mansect"><a name="tag_20_90_11" id="tag_20_90_11"></a>STDERR</h4>
191 <blockquote>
192 <p>The standard error shall be used only for diagnostic messages.</p>
193 </blockquote>
194 <h4 class="mansect"><a name="tag_20_90_12" id="tag_20_90_12"></a>OUTPUT FILES</h4>
195 <blockquote>
196 <p>None.</p>
197 </blockquote>
198 <h4 class="mansect"><a name="tag_20_90_13" id="tag_20_90_13"></a>EXTENDED DESCRIPTION</h4>
199 <blockquote>
200 <p>The <i>od</i> utility shall copy sequentially each input file to standard output, transforming the input data according to the
201 output types specified by the <b>-t</b> option <sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src=
202 "../images/opt-start.gif" alt="[Option Start]" border="0"> or the <b>-bcdosx</b> options. <img src="../images/opt-end.gif"
203 alt="[Option End]" border="0"> If no output type is specified, the default output shall be as if <b>-t oS</b> had been
204 specified.</p>
205 <p>The number of bytes transformed by the output type specifier <tt>c</tt> may be variable depending on the <i>LC_CTYPE</i>
206 category.</p>
207 <p>The default number of bytes transformed by output type specifiers <tt>d</tt>, <tt>f</tt>, <tt>o</tt>, <tt>u</tt>, and <tt>x</tt>
208 corresponds to the various C-language types as follows. If the <a href="../utilities/c17.html"><i>c17</i></a> compiler is present
209 on the system, these specifiers shall correspond to the sizes used by default in that compiler. Otherwise, these sizes may vary
210 among systems that conform to POSIX.1-2024.</p>
211 <ul>
212 <li>
213 <p>For the type specifier characters <tt>d</tt>, <tt>o</tt>, <tt>u</tt>, and <tt>x</tt>, the default number of bytes shall
214 correspond to the size of the underlying implementation's basic integer type. For these specifier characters, the implementation
215 shall support values of the optional number of bytes to be converted corresponding to the number of bytes in the C-language types
216 <b>char</b>, <b>short</b>, <b>int</b>, and <b>long</b>. These numbers can also be specified by an application as the characters
217 <tt>'C'</tt>, <tt>'S'</tt>, <tt>'I'</tt>, and <tt>'L'</tt>, respectively. The implementation shall also support the values 1, 2, 4,
218 and 8, even if it provides no C-Language types of those sizes. The implementation shall support the decimal value corresponding to
219 the C-language type <b>long long</b>. The byte order used when interpreting numeric values is implementation-defined, but shall
220 correspond to the order in which a constant of the corresponding type is stored in memory on the system.</p>
221 </li>
222 <li>
223 <p>For the type specifier character <tt>f</tt>, the default number of bytes shall correspond to the number of bytes in the
224 underlying implementation's basic double precision floating-point data type. The implementation shall support values of the
225 optional number of bytes to be converted corresponding to the number of bytes in the C-language types <b>float,</b> <b>double</b>,
226 and <b>long double</b>. These numbers can also be specified by an application as the characters <tt>'F'</tt>, <tt>'D'</tt>, and
227 <tt>'L'</tt>, respectively.</p>
228 </li>
229 </ul>
230 <p>The type specifier character <tt>a</tt> specifies that bytes shall be interpreted as named characters from the International
231 Reference Version (IRV) of the ISO/IEC 646:1991 standard. Only the least significant seven bits of each byte shall be used for
232 this type specification. Bytes with the values listed in the following table shall be written using the corresponding names for
233 those characters.<br></p>
234 <p class="caption">Table: Named Characters in <i>od</i></p>
235 <center>
236 <table border="1" cellpadding="3" align="center">
237 <tr valign="top">
238 <th align="center">
239 <p class="tent"><b>Value</b></p>
240 </th>
241 <th align="center">
242 <p class="tent"><b>Name</b></p>
243 </th>
244 <th align="center">
245 <p class="tent"><b>Value</b></p>
246 </th>
247 <th align="center">
248 <p class="tent"><b>Name</b></p>
249 </th>
250 <th align="center">
251 <p class="tent"><b>Value</b></p>
252 </th>
253 <th align="center">
254 <p class="tent"><b>Name</b></p>
255 </th>
256 <th align="center">
257 <p class="tent"><b>Value</b></p>
258 </th>
259 <th align="center">
260 <p class="tent"><b>Name</b></p>
261 </th>
262 </tr>
263 <tr valign="top">
264 <td align="left">
265 <p class="tent">\000</p>
266 </td>
267 <td align="left">
268 <p class="tent"><b>nul</b></p>
269 </td>
270 <td align="left">
271 <p class="tent">\001</p>
272 </td>
273 <td align="left">
274 <p class="tent"><b>soh</b></p>
275 </td>
276 <td align="left">
277 <p class="tent">\002</p>
278 </td>
279 <td align="left">
280 <p class="tent"><b>stx</b></p>
281 </td>
282 <td align="left">
283 <p class="tent">\003</p>
284 </td>
285 <td align="left">
286 <p class="tent"><b>etx</b></p>
287 </td>
288 </tr>
289 <tr valign="top">
290 <td align="left">
291 <p class="tent">\004</p>
292 </td>
293 <td align="left">
294 <p class="tent"><b>eot</b></p>
295 </td>
296 <td align="left">
297 <p class="tent">\005</p>
298 </td>
299 <td align="left">
300 <p class="tent"><b>enq</b></p>
301 </td>
302 <td align="left">
303 <p class="tent">\006</p>
304 </td>
305 <td align="left">
306 <p class="tent"><b>ack</b></p>
307 </td>
308 <td align="left">
309 <p class="tent">\007</p>
310 </td>
311 <td align="left">
312 <p class="tent"><b>bel</b></p>
313 </td>
314 </tr>
315 <tr valign="top">
316 <td align="left">
317 <p class="tent">\010</p>
318 </td>
319 <td align="left">
320 <p class="tent"><b>bs</b></p>
321 </td>
322 <td align="left">
323 <p class="tent">\011</p>
324 </td>
325 <td align="left">
326 <p class="tent"><b>ht</b></p>
327 </td>
328 <td align="left">
329 <p class="tent">\012</p>
330 </td>
331 <td align="left">
332 <p class="tent"><b>lf or nl<sup><small>*</small></sup></b></p>
333 </td>
334 <td align="left">
335 <p class="tent">\013</p>
336 </td>
337 <td align="left">
338 <p class="tent"><b>vt</b></p>
339 </td>
340 </tr>
341 <tr valign="top">
342 <td align="left">
343 <p class="tent">\014</p>
344 </td>
345 <td align="left">
346 <p class="tent"><b>ff</b></p>
347 </td>
348 <td align="left">
349 <p class="tent">\015</p>
350 </td>
351 <td align="left">
352 <p class="tent"><b>cr</b></p>
353 </td>
354 <td align="left">
355 <p class="tent">\016</p>
356 </td>
357 <td align="left">
358 <p class="tent"><b>so</b></p>
359 </td>
360 <td align="left">
361 <p class="tent">\017</p>
362 </td>
363 <td align="left">
364 <p class="tent"><b>si</b></p>
365 </td>
366 </tr>
367 <tr valign="top">
368 <td align="left">
369 <p class="tent">\020</p>
370 </td>
371 <td align="left">
372 <p class="tent"><b>dle</b></p>
373 </td>
374 <td align="left">
375 <p class="tent">\021</p>
376 </td>
377 <td align="left">
378 <p class="tent"><b>dc1</b></p>
379 </td>
380 <td align="left">
381 <p class="tent">\022</p>
382 </td>
383 <td align="left">
384 <p class="tent"><b>dc2</b></p>
385 </td>
386 <td align="left">
387 <p class="tent">\023</p>
388 </td>
389 <td align="left">
390 <p class="tent"><b>dc3</b></p>
391 </td>
392 </tr>
393 <tr valign="top">
394 <td align="left">
395 <p class="tent">\024</p>
396 </td>
397 <td align="left">
398 <p class="tent"><b>dc4</b></p>
399 </td>
400 <td align="left">
401 <p class="tent">\025</p>
402 </td>
403 <td align="left">
404 <p class="tent"><b>nak</b></p>
405 </td>
406 <td align="left">
407 <p class="tent">\026</p>
408 </td>
409 <td align="left">
410 <p class="tent"><b>syn</b></p>
411 </td>
412 <td align="left">
413 <p class="tent">\027</p>
414 </td>
415 <td align="left">
416 <p class="tent"><b>etb</b></p>
417 </td>
418 </tr>
419 <tr valign="top">
420 <td align="left">
421 <p class="tent">\030</p>
422 </td>
423 <td align="left">
424 <p class="tent"><b>can</b></p>
425 </td>
426 <td align="left">
427 <p class="tent">\031</p>
428 </td>
429 <td align="left">
430 <p class="tent"><b>em</b></p>
431 </td>
432 <td align="left">
433 <p class="tent">\032</p>
434 </td>
435 <td align="left">
436 <p class="tent"><b>sub</b></p>
437 </td>
438 <td align="left">
439 <p class="tent">\033</p>
440 </td>
441 <td align="left">
442 <p class="tent"><b>esc</b></p>
443 </td>
444 </tr>
445 <tr valign="top">
446 <td align="left">
447 <p class="tent">\034</p>
448 </td>
449 <td align="left">
450 <p class="tent"><b>fs</b></p>
451 </td>
452 <td align="left">
453 <p class="tent">\035</p>
454 </td>
455 <td align="left">
456 <p class="tent"><b>gs</b></p>
457 </td>
458 <td align="left">
459 <p class="tent">\036</p>
460 </td>
461 <td align="left">
462 <p class="tent"><b>rs</b></p>
463 </td>
464 <td align="left">
465 <p class="tent">\037</p>
466 </td>
467 <td align="left">
468 <p class="tent"><b>us</b></p>
469 </td>
470 </tr>
471 <tr valign="top">
472 <td align="left">
473 <p class="tent">\040</p>
474 </td>
475 <td align="left">
476 <p class="tent"><b>sp</b></p>
477 </td>
478 <td align="left">
479 <p class="tent">\177</p>
480 </td>
481 <td align="left">
482 <p class="tent"><b>del</b></p>
483 </td>
484 <td align="left">
485 <p class="tent"> </p>
486 </td>
487 <td align="left">
488 <p class="tent"><b> </b></p>
489 </td>
490 <td align="left">
491 <p class="tent"> </p>
492 </td>
493 <td align="left">
494 <p class="tent"><b> </b></p>
495 </td>
496 </tr>
497 </table>
498 </center>
499 <basefont size="2">
500 <dl>
501 <dt><b>Note:</b></dt>
502 <dd>The <tt>"\012"</tt> value may be written either as <b>lf</b> or <b>nl</b>.</dd>
503 </dl>
504 <basefont size="3">
505 <p class="tent">The type specifier character <tt>c</tt> specifies that bytes shall be interpreted as characters specified by the
506 current setting of the <i>LC_CTYPE</i> locale category. Characters listed in the table in XBD <a href=
507 "../basedefs/V1_chap05.html#tag_05"><i>5. File Format Notation</i></a> (<tt>'\\'</tt>, <tt>'\a'</tt>, <tt>'\b'</tt>, <tt>'\f'</tt>,
508 <tt>'\n'</tt>, <tt>'\r'</tt>, <tt>'\t'</tt>, <tt>'\v'</tt>) shall be written as the corresponding escape sequences, except that
509 <backslash> shall be written as a single <backslash> and a NUL shall be written as <tt>'\0'</tt>. Other non-printable
510 characters shall be written as one three-digit octal number for each byte in the character. Printable multi-byte characters shall
511 be written in the area corresponding to the first byte of the character; the two-character sequence <tt>"**"</tt> shall be written
512 in the area corresponding to each remaining byte in the character, as an indication that the character is continued. When either
513 the <b>-j</b> <i>skip</i> or <b>-N</b> <i>count</i> option is specified along with the <tt>c</tt> type specifier, and this results
514 in an attempt to start or finish in the middle of a multi-byte character, the result is implementation-defined.</p>
515 <p class="tent">The input data shall be manipulated in blocks, where a block is defined as a multiple of the least common multiple
516 of the number of bytes transformed by the specified output types. If the least common multiple is greater than 16, the results are
517 unspecified. Each input block shall be written as transformed by each output type, one per written line, in the order that the
518 output types were specified. If the input block size is larger than the number of bytes transformed by the output type, the output
519 type shall sequentially transform the parts of the input block, and the output from each of the transformations shall be separated
520 by one or more <blank> characters.</p>
521 <p class="tent">If, as a result of the specification of the <b>-N</b> option or end-of-file being reached on the last input file,
522 input data only partially satisfies an output type, the input shall be extended sufficiently with null bytes to write the last byte
523 of the input.</p>
524 <p class="tent">Unless <b>-A n</b> is specified, the first output line produced for each input block shall be preceded by the
525 input offset, cumulative across input files, of the next byte to be written. The format of the input offset is unspecified;
526 however, it shall not contain any <blank> characters, shall start at the first character of the output line, and shall be
527 followed by one or more <blank> characters. In addition, the offset of the byte following the last byte written shall be
528 written after all the input data has been processed, but shall not be followed by any <blank> characters. If <b>-A n</b>
529 is specified, it is unspecified whether the line that would contain this final offset is written as an empty line or is not
530 written.</p>
531 <p class="tent">If no <b>-A</b> option is specified, the input offset base is unspecified.</p>
532 </blockquote>
533 <h4 class="mansect"><a name="tag_20_90_14" id="tag_20_90_14"></a>EXIT STATUS</h4>
534 <blockquote>
535 <p>The following exit values shall be returned:</p>
536 <dl compact>
537 <dd></dd>
538 <dt> 0</dt>
539 <dd>All input files were processed successfully.</dd>
540 <dt>>0</dt>
541 <dd>An error occurred.</dd>
542 </dl>
543 </blockquote>
544 <h4 class="mansect"><a name="tag_20_90_15" id="tag_20_90_15"></a>CONSEQUENCES OF ERRORS</h4>
545 <blockquote>
546 <p>Default.</p>
547 </blockquote>
548 <hr>
549 <div class="box"><em>The following sections are informative.</em></div>
550 <h4 class="mansect"><a name="tag_20_90_16" id="tag_20_90_16"></a>APPLICATION USAGE</h4>
551 <blockquote>
552 <p>XSI-conformant applications are warned not to use filenames starting with <tt>'+'</tt> or a first operand starting with a
553 numeric character so that the old functionality can be maintained by implementations, unless they specify one of the <b>-A</b>,
554 <b>-j</b>, or <b>-N</b> options. To guarantee that one of these filenames is always interpreted as a filename, an application could
555 always specify the address base format with the <b>-A</b> option.</p>
556 </blockquote>
557 <h4 class="mansect"><a name="tag_20_90_17" id="tag_20_90_17"></a>EXAMPLES</h4>
558 <blockquote>
559 <p>If a file containing 128 bytes with decimal values zero to 127, in increasing order, is supplied as standard input to the
560 command:</p>
561 <pre>
562 <tt>od -A d -t a
563 </tt></pre>
564 <p class="tent">on an implementation using an input block size of 16 bytes, the standard output, independent of the current locale
565 setting, would be similar to:</p>
566 <pre>
567 <tt>0000000 nul soh stx etx eot enq ack bel bs ht nl vt ff cr so si
568 0000016 dle dc1 dc2 dc3 dc4 nak syn etb can em sub esc fs gs rs us
569 0000032 sp ! " # $ % & ' ( ) * + , - . /
570 0000048 0 1 2 3 4 5 6 7 8 9 : ; < = > ?
571 0000064 @ A B C D E F G H I J K L M N O
572 0000080 P Q R S T U V W X Y Z [ \ ] ^ _
573 0000096 ` a b c d e f g h i j k l m n o
574 0000112 p q r s t u v w x y z { | } ~ del
575 0000128
576 </tt></pre>
577 <p class="tent">Note that this volume of POSIX.1-2024 allows <b>nl</b> or <b>lf</b> to be used as the name for the
578 ISO/IEC 646:1991 standard IRV character with decimal value 10. The IRV names this character <b>lf</b> (line feed), but
579 traditional implementations have referred to this character as newline (<b>nl</b>) and the POSIX locale character set symbolic name
580 for the corresponding character is a <newline>.</p>
581 <p class="tent">The command:</p>
582 <pre>
583 <tt>od -A o -t o2x2x -N 18
584 </tt></pre>
585 <p class="tent">on a system with 32-bit words and an implementation using an input block size of 16 bytes could write 18 bytes in
586 approximately the following format:</p>
587 <pre>
588 <tt>0000000 032056 031440 041123 042040 052516 044530 020043 031464
589 342e 3320 4253 4420 554e 4958 2023 3334
590 342e3320 42534420 554e4958 20233334
591 0000020 032472
592 353a
593 353a0000
594 0000022
595 </tt></pre>
596 <p class="tent">The command:</p>
597 <pre>
598 <tt>od -A d -t f -t o4 -t x4 -N 24 -j 0x15
599 </tt></pre>
600 <p class="tent">on a system with 64-bit doubles (for example, IEEE Std 754-1985 double precision floating-point format)
601 would skip 21 bytes of input data and then write 24 bytes in approximately the following format:</p>
602 <pre>
603 <tt>0000000 1.00000000000000e+00 1.57350000000000e+01
604 07774000000 00000000000 10013674121 35341217270
605 3ff00000 00000000 402f3851 eb851eb8
606 0000016 1.40668230000000e+02
607 10030312542 04370303230
608 40619562 23e18698
609 0000024
610 </tt></pre></blockquote>
611 <h4 class="mansect"><a name="tag_20_90_18" id="tag_20_90_18"></a>RATIONALE</h4>
612 <blockquote>
613 <p>The <i>od</i> utility went through several names in early proposals, including <i>hd</i>, <i>xd</i>, and most recently
614 <i>hexdump</i>. There were several objections to all of these based on the following reasons:</p>
615 <ul>
616 <li class="tent">The <i>hd</i> and <i>xd</i> names conflicted with historical utilities that behaved differently.</li>
617 <li class="tent">The <i>hexdump</i> description was much more complex than needed for a simple dump utility.</li>
618 <li class="tent">The <i>od</i> utility has been available on all historical implementations and there was no need to create a new
619 name for a utility so similar to the historical <i>od</i> utility.</li>
620 </ul>
621 <p class="tent">The original reasons for not standardizing historical <i>od</i> were also fairly widespread. Those reasons are
622 given below along with rationale explaining why the standard developers believe that this version does not suffer from the
623 indicated problem:</p>
624 <ul>
625 <li class="tent">The BSD and System V versions of <i>od</i> have diverged, and the intersection of features provided by both does
626 not meet the needs of the user community. In fact, the System V version only provides a mechanism for dumping octal bytes and
627 <b>short</b>s, signed and unsigned decimal <b>short</b>s, hexadecimal <b>short</b>s, and ASCII characters. BSD added the ability to
628 dump <b>float</b>s, <b>double</b>s, named ASCII characters, and octal, signed decimal, unsigned decimal, and hexadecimal
629 <b>long</b>s. The version presented here provides more normalized forms for dumping bytes, <b>short</b>s, <b>int</b>s, and
630 <b>long</b>s in octal, signed decimal, unsigned decimal, and hexadecimal; <b>float</b>, <b>double</b>, and <b>long double</b>; and
631 named ASCII as well as current locale characters.</li>
632 <li class="tent">It would not be possible to come up with a compatible superset of the BSD and System V flags that met the
633 requirements of the standard developers. The historical default <i>od</i> output is the specified default output of this utility.
634 None of the option letters chosen for this version of <i>od</i> conflict with any of the options to historical versions of
635 <i>od</i>.</li>
636 <li class="tent">On systems with different sizes for <b>short</b>, <b>int</b>, and <b>long</b>, there was no way to ask for dumps
637 of <b>int</b>s, even in the BSD version. Because of the way options are named, the name space could not be extended to solve these
638 problems. This is why the <b>-t</b> option was added (with type specifiers more closely matched to the <a href=
639 "../functions/printf.html"><i>printf</i>()</a> formats used in the rest of this volume of POSIX.1-2024) and the optional field
640 sizes were added to the <tt>d</tt>, <tt>f</tt>, <tt>o</tt>, <tt>u</tt>, and <tt>x</tt> type specifiers. It is also one of the
641 reasons why the historical practice was not mandated as a required obsolescent form of <i>od</i>. (Although the old versions of
642 <i>od</i> are not listed as an obsolescent form, implementations are urged to continue to recognize the older forms for several
643 more years.) The <tt>a</tt>, <tt>c</tt>, <tt>f</tt>, <tt>o</tt>, and <tt>x</tt> types match the meaning of the corresponding format
644 characters in the historical implementations of <i>od</i> except for the default sizes of the fields converted. The <tt>d</tt>
645 format is signed in this volume of POSIX.1-2024 to match the <a href="../functions/printf.html"><i>printf</i>()</a> notation.
646 (Historical versions of <i>od</i> used <tt>d</tt> as a synonym for <tt>u</tt> in this version. The System V implementation uses
647 <tt>s</tt> for signed decimal; BSD uses <tt>i</tt> for signed decimal and <tt>s</tt> for null-terminated strings.) Other than
648 <tt>d</tt> and <tt>u</tt>, all of the type specifiers match format characters in the historical BSD version of <b>od</b>.
649 <p class="tent">The sizes of the C-language types <b>char</b>, <b>short</b>, <b>int</b>, <b>long</b>, <b>float</b>, <b>double</b>,
650 and <b>long double</b> are used even though it is recognized that there may be zero or more than one compiler for the C language on
651 an implementation and that they may use different sizes for some of these types. (For example, one compiler might use 2 bytes
652 <b>short</b>s, 2 bytes <b>int</b>s, and 4 bytes <b>long</b>s, while another compiler (or an option to the same compiler) uses 2
653 bytes <b>short</b>s, 4 bytes <b>int</b>s, and 4 bytes <b>long</b>s.) Nonetheless, there has to be a basic size known by the
654 implementation for these types, corresponding to the values reported by invocations of the <a href=
655 "../utilities/getconf.html"><i>getconf</i></a> utility when called with <i>system_var</i> operands {UCHAR_MAX}, {USHORT_MAX},
656 {UINT_MAX}, and {ULONG_MAX} for the types <b>char</b>, <b>short</b>, <b>int</b>, and <b>long</b>, respectively. There are similar
657 constants required by the ISO C standard, but not required by the System Interfaces volume of POSIX.1-2024 or this volume of
658 POSIX.1-2024. They are {FLT_MANT_DIG}, {DBL_MANT_DIG}, and {LDBL_MANT_DIG} for the types <b>float</b>, <b>double</b>, and <b>long
659 double</b>, respectively. If the optional <a href="../utilities/c17.html"><i>c17</i></a> utility is provided by the implementation
660 and used as specified by this volume of POSIX.1-2024, these are the sizes that would be provided. If an option is used that
661 specifies different sizes for these types, there is no guarantee that the <i>od</i> utility is able to interpret binary data output
662 by such a program correctly.</p>
663 <p class="tent">This volume of POSIX.1-2024 requires that the numeric values of these lengths be recognized by the <i>od</i>
664 utility and that symbolic forms also be recognized. Thus, a conforming application can always look at an array of <b>unsigned
665 long</b> data elements using <i>od</i> <b>-t</b> <i>uL</i>.</p>
666 </li>
667 <li class="tent">The method of specifying the format for the address field based on specifying a starting offset in a file
668 unnecessarily tied the two together. The <b>-A</b> option now specifies the address base and the <b>-S</b> option specifies a
669 starting offset.</li>
670 <li class="tent">It would be difficult to break the dependence on US ASCII to achieve an internationalized utility. It does not
671 seem to be any harder for <i>od</i> to dump characters in the current locale than it is for the <a href=
672 "../utilities/ed.html"><i>ed</i></a> or <a href="../utilities/sed.html"><i>sed</i></a> <b>l</b> commands. The <tt>c</tt> type
673 specifier does this without difficulty and is completely compatible with the historical implementations of the <b>c</b> format
674 character when the current locale uses a superset of the ISO/IEC 646:1991 standard as a codeset. The <tt>a</tt> type specifier
675 (from the BSD <b>a</b> format character) was left as a portable means to dump ASCII (or more correctly ISO/IEC 646:1991
676 standard (IRV)) so that headers produced by <a href="../utilities/pax.html"><i>pax</i></a> could be deciphered even on systems that
677 do not use the ISO/IEC 646:1991 standard as a subset of their base codeset.</li>
678 </ul>
679 <p class="tent">The use of <tt>"**"</tt> as an indication of continuation of a multi-byte character in <tt>c</tt> specifier output
680 was chosen based on seeing an implementation that uses this method. The continuation bytes have to be marked in a way that is not
681 ambiguous with another single-byte or multi-byte character.</p>
682 <p class="tent">An early proposal used <b>-S</b> and <b>-n</b>, respectively, for the <b>-j</b> and <b>-N</b> options eventually
683 selected. These were changed to avoid conflicts with historical implementations.</p>
684 <p class="tent">The original standard specified <b>-t o2</b> as the default when no output type was given. This was changed to
685 <b>-t oS</b> (the length of a <b>short</b>) to accommodate a supercomputer implementation that historically used 64 bits as its
686 default (and that defined shorts as 64 bits). This change should not affect conforming applications. The requirement to support
687 lengths of 1, 2, and 4 was added at the same time to address an historical implementation that had no two-byte data types in its C
688 compiler.</p>
689 <p class="tent">The use of a basic integer data type is intended to allow the implementation to choose a word size commonly used by
690 applications on that architecture.</p>
691 <p class="tent">Earlier versions of this standard allowed for implementations with bytes other than eight bits, but this has been
692 modified in this version.</p>
693 </blockquote>
694 <h4 class="mansect"><a name="tag_20_90_19" id="tag_20_90_19"></a>FUTURE DIRECTIONS</h4>
695 <blockquote>
696 <p>All option and operand interfaces marked XSI may be removed in a future version.</p>
697 </blockquote>
698 <h4 class="mansect"><a name="tag_20_90_20" id="tag_20_90_20"></a>SEE ALSO</h4>
699 <blockquote>
700 <p><a href="../utilities/c17.html#"><i>c17</i></a> , <a href="../utilities/sed.html#"><i>sed</i></a></p>
701 <p class="tent">XBD <a href="../basedefs/V1_chap05.html#tag_05"><i>5. File Format Notation</i></a> , <a href=
702 "../basedefs/V1_chap08.html#tag_08"><i>8. Environment Variables</i></a> , <a href="../basedefs/V1_chap12.html#tag_12_02"><i>12.2
703 Utility Syntax Guidelines</i></a></p>
704 </blockquote>
705 <h4 class="mansect"><a name="tag_20_90_21" id="tag_20_90_21"></a>CHANGE HISTORY</h4>
706 <blockquote>
707 <p>First released in Issue 2.</p>
708 </blockquote>
709 <h4 class="mansect"><a name="tag_20_90_22" id="tag_20_90_22"></a>Issue 5</h4>
710 <blockquote>
711 <p>In the description of the <b>-c</b> option, the phrase "This is equivalent to <b>-t c</b>." is deleted.</p>
712 <p class="tent">The FUTURE DIRECTIONS section is modified.</p>
713 </blockquote>
714 <h4 class="mansect"><a name="tag_20_90_23" id="tag_20_90_23"></a>Issue 6</h4>
715 <blockquote>
716 <p>The <i>od</i> utility is changed to remove the assumption that <b>short</b> was a two-byte entity, as per the revisions in the
717 IEEE P1003.2b draft standard.</p>
718 <p class="tent">The normative text is reworded to avoid use of the term "must" for application requirements.</p>
719 <p class="tent">IEEE Std 1003.1-2001/Cor 1-2002, item XCU/TC1/D6/33 is applied, correcting the examples which used
720 an undefined <b>-n</b> option, which should have been <b>-N</b>.</p>
721 <p class="tent">IEEE Std 1003.1-2001/Cor 2-2004, item XCU/TC2/D6/19 is applied, removing text describing behavior on
722 systems with bytes consisting of more than eight bits.</p>
723 </blockquote>
724 <h4 class="mansect"><a name="tag_20_90_24" id="tag_20_90_24"></a>Issue 7</h4>
725 <blockquote>
726 <p>Austin Group Interpretation 1003.1-2001 #092 is applied.</p>
727 <p class="tent">SD5-XCU-ERN-37 is applied, updating the OPERANDS section.</p>
728 <p class="tent">SD5-XCU-ERN-97 is applied, updating the SYNOPSIS.</p>
729 </blockquote>
730 <h4 class="mansect"><a name="tag_20_90_25" id="tag_20_90_25"></a>Issue 8</h4>
731 <blockquote>
732 <p>Austin Group Defect 1017 is applied, clarifying that when <b>-A n</b> is specified, the line that would contain the final
733 offset can either be written as an empty line or not be written.</p>
734 <p class="tent">Austin Group Defect 1122 is applied, changing the description of <i>NLSPATH .</i></p>
735 </blockquote>
736 <div class="box"><em>End of informative text.</em></div>
737 <hr>
738 <p> </p>
739 <a href="#top"><span class="topOfPage">return to top of page</span></a><br>
740 <hr size="2" noshade>
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