19 lines
2.9 KiB
HTML
19 lines
2.9 KiB
HTML
<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>dd</title><link rel="stylesheet" href="../../jargon.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.61.0"/><link rel="home" href="../index.html" title="The Jargon File"/><link rel="up" href="../D.html" title="D"/><link rel="previous" href="day-mode.html" title="day mode"/><link rel="next" href="DDT.html" title="DDT"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">dd</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="day-mode.html">Prev</a> </td><th width="60%" align="center">D</th><td width="20%" align="right"> <a accesskey="n" href="DDT.html">Next</a></td></tr></table><hr/></div><dt><a id="dd"/><dt xmlns="" id="dd"><b>dd</b>: <span xmlns="http://www.w3.org/1999/xhtml" class="pronunciation">/dee·dee/</span>, <span xmlns="http://www.w3.org/1999/xhtml" class="grammar">vt.</span></dt></dt><dd><p> [Unix: from IBM <a href="../J/JCL.html"><i class="glossterm">JCL</i></a>] Equivalent to
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<a href="../C/cat.html"><i class="glossterm">cat</i></a> or <a href="../B/BLT.html"><i class="glossterm">BLT</i></a>. Originally the
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name of a Unix copy command with special options suitable for
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block-oriented devices; it was often used in heavy-handed system
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maintenance, as in “<span class="quote">Let's <b class="command">dd</b> the root
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partition onto a tape, then use the boot PROM to load it back on to a new
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disk</span>”. The Unix
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<span class="citerefentry"><span class="refentrytitle">dd</span>(1)</span>
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was designed with a weird, distinctly non-Unixy keyword option syntax
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reminiscent of IBM System/360 JCL (which had an elaborate DD ‘Dataset
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Definition’ specification for I/O devices); though the command filled
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a need, the interface design was clearly a prank. The jargon usage is now
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very rare outside Unix sites and now nearly obsolete even there, as
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<span class="citerefentry"><span class="refentrytitle">dd</span>(1)</span>
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has been <a href="deprecated.html"><i class="glossterm">deprecated</i></a> for a long time (though it has
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no exact replacement). The term has been displaced by
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<a href="../B/BLT.html"><i class="glossterm">BLT</i></a> or simple English ‘copy’.</p></dd><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="day-mode.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="../D.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="DDT.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">day mode </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> DDT</td></tr></table></div></body></html>
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