Hyper Dictionary

English Dictionary Computer Dictionary Video Dictionary Thesaurus Dream Dictionary Medical Dictionary

Search Dictionary:  

Meaning of DD

Computing Dictionary
  1. 1. double density.

    2. data dictionary.

    [jargon file]

  2. A unix copy command with special options suitable for block-oriented devices; it was often used in heavy-handed system maintenance, as in "Let's "dd" the root partition onto a tape, then use the boot prom to load it back on to a new disk".

    The Unix "dd" was designed with a weird, distinctly non-Unixy keyword option syntax reminiscent of ibm system/360 JCL (which had an elaborate DD "Dataset Definition" specification for I/O devices); though the command filled a need, the interface design was clearly a prank.

    The jargon usage is now very rare outside Unix sites and now nearly obsolete even there, as "dd" has been deprecated for a long time (though it has no exact replacement). The term has been displaced by blt or simple English "copy".

    [jargon file]