DD(1) DD(1) NAME dd - convert and copy a file SYNOPSIS dd [option=value] ... DESCRIPTION Dd 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. option values if=file input file name; standard input is default of=file 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, super- seding ibs and obs; also, if no conversion is specified, preserve the input block size instead of packing short blocks into the output buffer. This is particularly effi- cient since no in-core copy need be done. cbs=n conversion buffer size skip=n skip n input records before starting copy files=n copy and concatenate n input files before terminating (makes sense only where input is a magtape or similar device). 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 ASCII records to fixed length unblock convert fixed length ASCII records to vari- able 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 ibs ... , ... 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 sepa- rated by x to indicate a product. DD(1) DD(1) Cbs is used only if ascii, unblock, ebcdic, ibm, or block conversion is specified. In the first two cases, cbs char- acters are copied into the conversion buffer, any specified character mapping is done, trailing blanks are trimmed and new-line is added before sending the line to the output. In the latter three cases, characters are read into the conver- sion buffer and blanks are added to make up an output record of size cbs. If cbs is unspecified or zero, the ascii, ebcdic, and ibm options convert the character set without changing the block structure of the input file; the unblock and block options become a simple file copy. After completion, dd reports the number of whole and partial input and output blocks. EXAMPLE dd if=/dev/rmt0 of=x ibs=800 cbs=80 conv=ascii,lcase Read an EBCDIC tape blocked ten 80-byte EBCDIC card images per record into an ASCII file. Note the use of raw magtape to handle arbitrary record sizes. SEE ALSO cp(1), tar(1), cpio(1) DIAGNOSTICS f+p records in(out) numbers of full and partial records read(written) .}f 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.