32v 1m dd

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DD(1) UNIX Programmer's Manual DD(1)


    dd - convert and copy a file


    dd [option=value] ...


    _D_d copies the specified input file to the specified output
    with possible conversions.  The standard input and output
    are used by default.  The input and output block size may be
    specified to take advantage of raw physical I/O.
    _o_p_t_i_o_n         _v_a_l_u_e_s
    if=            input file name; standard input is default
    of=            output file name; standard output is default
    ibs=_n          input block size _n bytes (default 512)
    obs=_n          output block size (default 512)
    bs=_n           set both input and output block size,
                   superseding _i_b_s and _o_b_s; also, if no conver-
                   sion is specified, it is particularly effi-
                   cient since no copy need be done
    cbs=_n          conversion buffer size
    skip=_n         skip _n input records before starting copy
    files=_n        skip _n input files before starting copy
    seek=_n         seek _n records from beginning of output file
                   before copying
    count=_n        copy only _n input records
    conv=ascii     convert EBCDIC to ASCII
         ebcdic    convert ASCII to EBCDIC
         ibm       slightly different map of ASCII to EBCDIC
         lcase     map alphabetics to lower case
         ucase     map alphabetics to upper case
         swab      swap every pair of bytes
         noerror   do not stop processing on an error
         sync      pad every input record to _i_b_s
         ... , ... several comma-separated conversions
    Where sizes are specified, a number of bytes is expected.  A
    number may end with k, b or w to specify multiplication by
    1024, 512, or 2 respectively; a pair of numbers may be
    separated by x to indicate a product.
    _C_b_s is used only if _a_s_c_i_i or _e_b_c_d_i_c conversion is specified.
    In the former case _c_b_s characters are placed into the
    conversion buffer, converted to ASCII, and trailing blanks
    trimmed and new-line added before sending the line to the
    output.  In the latter case ASCII characters are read into
    the conversion buffer, converted to EBCDIC, and blanks added
    to make up an output record of size _c_b_s.
    After completion, _d_d reports the number of whole and partial
    input and output blocks.
    For example, to read an EBCDIC tape blocked ten 80-byte
    EBCDIC card images per record into the ASCII file _x:

         dd if=/dev/rmt0 of=x ibs=800 cbs=80 conv=ascii,lcase
    Note the use of raw magtape.  _D_d is especially suited to I/O
    on the raw physical devices because it allows reading and
    writing in arbitrary record sizes.


    cp(1), tr(1)


    f+p records in(out): numbers of full and partial records


    The ASCII/EBCDIC conversion tables are taken from the 256
    character standard in the CACM Nov, 1968.  The `ibm' conver-
    sion, while less blessed as a standard, corresponds better
    to certain IBM print train conventions.  There is no univer-
    sal solution.
    Newlines are inserted only on conversion to ASCII; padding
    is done only on conversion to EBCDIC.  These should be
    separate options.