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.\" @(#)dd.1 6.7 (Berkeley) 8/7/91
.Nd Convert and copy a file.
utility copies the standard input to the standard output.
Input data is read and written in 512-byte blocks.
If input reads are short, input from multiple reads are aggregated
to form the output block.
displays the number of complete and partial input and output blocks
and truncated input records to the standard error output.
The following operands are available:
Set both input and output block size, superseding the
If no conversion values other than
are specified, then each input block is copied to the output as a
single block without any aggregation of short blocks.
Set the conversion record size to
The conversion record size is required by the record oriented conversion
input files before terminating.
This operand is only applicable when the input device is a tape.
Set the input block size to
bytes instead of the default 512.
instead of the standard input.
Set the output block size to
bytes instead of the default 512.
instead of the standard output.
Any regular output file is truncated unless the
conversion value is specified.
If an initial portion of the output file is skipped (see the
the output file is truncated at that point.
blocks from the beginning of the output before copying.
Otherwise, existing blocks are read and the data discarded.
If the user does not have read permission for the tape, it is positioned
If the seek operation is past the end of file, space from the current
end of file to the specified offset is filled with blocks of
blocks from the beginning of the input before copying.
On input which supports seeks, a
Otherwise, input data is read and discarded.
For pipes, the correct number of bytes is read.
For all other devices, the correct number of blocks is read without
distinguishing between a partial or complete block being read.
.Ns Cm value Ns Op \&, Cm value \&...
is one of the symbols from the following list.
value except that characters are translated from
There are two conversion maps for
specifies the recommended one which is compatible with System V.
specifies the one used in historic
Treats the input as a sequence of newline or end-of-file terminated variable
length records independent of input and output block boundaries.
Any trailing newline character is discarded.
Each input record is converted to a fixed length output record where the
length is specified by the
Input records shorter than the conversion record size are padded with spaces.
Input records longer than the conversion record size are truncated.
The number of truncated input records, if any, are reported to the standard
error at the completion of the copy.
.It Cm ebcdic , ibm , oldebcdic , oldibm
value except that characters are translated from
There are four conversion maps for
specifies the recommended one which is compatible with
is a slightly different mapping, which is compatible with the
are maps used in historic
Transform uppercase characters into lowercase characters.
Do not stop processing on an input error.
When an input error occurs, a diagnostic message followed by the current
input and output block counts will be written to standard error in the
same format as the standard completion message.
conversion is also specified, any missing input data will be replaced
bytes (or with spaces if a block oriented conversion value was
specified) and processed as a normal input buffer.
conversion is not specified, the input block is omitted from the output.
On input files which are not tapes or pipes, the file offset
will be positioned past the block in which the error occurred using
Do not truncate the output file.
This will preserve any blocks in the output file not explicitly written
value is not supported for tapes.
Swap every pair of input bytes.
If an input buffer has an odd number of bytes, the last byte will be
Pad every input block to the input buffer size.
Spaces are used for pad bytes if a block oriented conversion value is
Transform lowercase characters into uppercase characters.
Treats the input as a sequence of fixed length records independent of input
and output block boundaries.
The length of the input records is specified by the
Any trailing space characters are discarded and a newline character is
Where sizes are specified, a decimal number of bytes is expected.
If the number ends with a ``b'', ``k'', ``m'' or ``w'', the number
is multiplied by 512, 1024 (1K), 1048576 (1M) or the number of bytes
in an integer, respectively.
Two or more numbers may be separated by an ``x'' to indicate a product.
displays the number of complete and partial input and output blocks,
truncated input records and odd-length byte-swapping blocks to the
A partial input block is one where less than the input block size
A partial output block is one where less than the output block size
Partial output blocks to tape devices are considered fatal errors.
Otherwise, the rest of the block will be written.
Partial output blocks to character devices will produce a warning message.
A truncated input block is one where a variable length record oriented
conversion value was specified and the input line was too long to
fit in the conversion record or was not newline terminated.
Normally, data resulting from input or conversion or both are aggregated
into output blocks of the specified size.
After the end of input is reached, any remaining output is written as
This means that the final output block may be shorter than the output
(see the ``status'' argument for
signal, the current input and output block counts will
be written to standard error in the same format as the standard completion
signal, the current input and output block counts will
be written to standard error in the same format as the standard completion
utility exits 0 on success and >0 if an error occurred.
utility is expected to be a superset of the
values are extensions to the