32v 1m dd
From Computer History Wiki
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.
f+p records in(out): numbers of full and partial records read(written)
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.