2014-04-26 10:52:28 -04:00
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dd
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2014-04-26 11:54:15 -04:00
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/deedee/ , vt. [Unix: from IBM JCL ] Equivalent to cat or BLT. Originally
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the 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 Let's dd the root partition onto a tape, then use the
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boot PROM to load it back on to a new disk. The Unix dd (1) was designed
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with a weird, distinctly non-Unixy keyword option syntax reminiscent of IBM
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System/360 JCL (which had an elaborate DD Dataset Definition specification
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for I/O devices); though the command filled a need, the interface design was
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clearly a prank. The jargon usage is now very rare outside Unix sites and
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now nearly obsolete even there, as dd (1) has been deprecated for a long
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time (though it has no exact replacement). The term has been displaced by
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BLT or simple English copy.
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