dd(1)
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dd Command
convert and copy a file
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SYNTAX
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, superseding
ibs and obs; also, if no conversion is specified,
it is particularly efficient since no in-core
copy need be done
cbs=n Conversion buffer size
skip=n Skip n input blocks before starting copy
iseek=n Seek n blocks from beginning of input file before
copying
oseek=n Seek n blocks from beginning of output file
before copying
count=n Copy only n input blocks
conv=ascii Convert EBCDIC to ASCII
ebcdic Convert ASCII to EBCDIC
ibm Slightly different map of ASCII to EBCDIC
lcase Map alphabetics to lowercase
ucase Map alphabetics to uppercase
swab Swap every pair of bytes
noerror Do not stop processing on an error
sync Pad every input block to ibs
... , ... Several comma-separated conversions
files=n Allows concatenation of multiple input files for
tape
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dd(1)
conv=block Convert to blocked files
conv=unblock Convert to unblocked files
Where sizes are specified, the 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.
Cbs is used only if ascii or ebcdic conversion is specified. In
the former case, cbs characters are placed into the conversion
buffer, converted to ASCII, 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 block of size
cbs.
After completion, dd reports the number of whole and partial
input and output blocks.
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EXAMPLES
$ cat file1
this file contains only lower case letters.
$ dd if=file1 of=file2 conv=ucase
$ cat file2
THIS FILE CONTAINS ONLY LOWER CASE LETTERS.
$
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SEE ALSO
cp(1).
DIAGNOSTICS
f+p blocks in(out) Numbers of full and partial blocks
read(written)
BUGS
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Licensed material--property of copyright holder(s)
dd(1)
The ASCII/EBCDIC conversion tables are taken from the 256-
character standard in the CACM Nov, 1968. These do not always
correspond to certain IBM (U.S. Registered Trademark) print train
conventions. There is no universal solution.
New-lines are inserted only on conversion to ASCII; padding is
done only on conversion to EBCDIC. These should be separate
options.
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Licensed material--property of copyright holder(s)