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

NAME
     dd - convert and copy a file

SYNTAX
     dd [option=value] ...

DESCRIPTION
     _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        copy _n files from (tape) input
     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 (includes rtrim)
          ebcdic    convert ASCII to EBCDIC (includes rfill)
          ibm       slightly different map of ASCII to EBCDIC
          rtrim     delete right blanks in _c_b_s and add a new line
          rfill     remove newline in _c_b_s and pad with blanks
          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 if _a_s_c_i_i, _r_t_r_i_m, _e_b_c_d_i_c, or _r_f_i_l_l conversion is
     specified.  In the former two cases _c_b_s characters are
     placed into the conversion buffer, converted to ASCII for
     case 1, and trailing blanks trimmed and new-line added
     before sending the line to the output.  In the latter two
     cases ASCII characters are read into the conversion buffer,
     converted to EBCDIC for case 3, and blanks added to make up
     an output record of size _c_b_s.  Only one of these conversions

Printed 5/16/83                                                 1

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

     or _i_b_m may be used at a time.

     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.

     To skip over a file before copying from magnetic tape do:

          (dd of=/dev/null; dd of=x) </dev/rmt0

SEE ALSO
     cp(1), mt(1), tar(1), tr(1)

DIAGNOSTICS
     f+p records in (out): numbers of full and partial records
     read (written).

BUGS
     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.

Printed 5/16/83                                                 2