ascii, oldascii
The same as the unblock value except that characters
are translated from EBCDIC to ASCII before the records
are converted. (These values imply unblock if the op-
erand cbs is also specified.) There are two conversion
maps for ASCII. The value ascii specifies the recom-
mended one which is compatible with AT&T System V UNIX.
The value oldascii specifies the one used in historic
AT&T UNIX and pre-4.3BSD-Reno systems.
block 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 new-
line character is discarded. Each input record is con-
verted to a fixed length output record where the length
is specified by the cbs operand. 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 output at
the completion of the copy.
ebcdic, ibm, oldebcdic, oldibm
The same as the block value except that characters are
translated from ASCII to EBCDIC after the records are
converted. (These values imply block if the operand
cbs is also specified.) There are four conversion maps
for EBCDIC. The value ebcdic specifies the recommended
one which is compatible with AT&T System V UNIX. The
value ibm is a slightly different mapping, which is
compatible with the AT&T System V UNIX ibm value. The
values oldebcdic and oldibm are maps used in historic
AT&T UNIX and pre-4.3BSD-Reno systems.
lcase Transform uppercase characters into lowercase charac-
ters.
noerror 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 writ-
ten to the standard error output in the same format as
the standard completion message. If the sync conver-
sion is also specified, any missing input data will be
replaced with NUL bytes (or with spaces if a block ori-
ented conversion value was specified) and processed as
a normal input buffer. If the sync 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 lseek(2).
notrunc Do not truncate the output file. This will preserve
any blocks in the output file not explicitly written by
dd. The notrunc value is not supported for tapes.
osync Pad the final output block to the full output block
size. If the input file is not a multiple of the out-
put block size after conversion, this conversion forces
the final output block to be the same size as preceding
blocks for use on devices that require regularly sized
blocks to be written. This option is incompatible with
use of the bs=n block size specification.
sparse If one or more output blocks would consist solely of
NUL bytes, try to seek the output file by the required
space instead of filling them with NULs, resulting in a
sparse file.
swab Swap every pair of input bytes. If an input buffer has
an odd number of bytes, the last byte will be ignored
during swapping.
sync Pad every input block to the input buffer size. Spaces
are used for pad bytes if a block oriented conversion
value is specified, otherwise NUL bytes are used.
ucase Transform lowercase characters into uppercase charac-
ters.
unblock 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 cbs op-
erand. Any trailing space characters are discarded and
a newline character is appended.