4BSD/usr/man/cat1/dd.1

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



NAME
     dd - convert and copy a file

SYNOPSIS
     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        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
          block     convert variable length records to fixed
                    length
          unblock   convert fixed length records to variable
                    length
          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, _u_n_b_l_o_c_k, _e_b_c_d_i_c, _i_b_m, or _b_l_o_c_k
     conversion is specified.  In the first two cases, _c_b_s char-
     acters are placed into the conversion buffer, any specified
     character mapping is done, trailing blanks trimmed and new-
     line added before sending the line to the output.  In the
     latter three cases, characters are read into the conversion



Printed 11/10/80                                                1






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



     buffer, 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.

SEE ALSO
     cp(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 11/10/80                                                2