irix - 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 sizes can be specified to take advantage of raw
physical I/O. dd processes supplementary code-set characters according
to the locale specified in the LC_CTYPE environment variable (see LANG in
environ(5)), except as noted below.
Option Values
if=file Input filename; standard input is default.
of=file Output filename; standard output is default.
ibs=n Input block size is n bytes (default 512).
obs=n Output block size is n bytes (default 512).
bs=n Set both input and output block size, superseding 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 efficient since no
in-core copy need be done).
cbs=n Conversion buffer size (logical record length).
files=n Copy and concatenate n input files before terminating
(makes sense only where input is a magnetic tape or
similar device).
skip=n Skip n input blocks before starting copy (appropriate for
magnetic tape, where iseek is undefined).
iseek=n Seek n blocks from beginning of input file before copying
(appropriate for disk files, where skip can be slow).
oseek=n Seek n blocks from beginning of output file before
copying. Preserves the contents (over the range of the
seek) of a previously existing output file.
seek=n Identical to oseek, retained for backward compatibility.
count=n Copy only n input blocks.
conv=ascii Convert EBCDIC to ASCII. Conversion results cannot be
assured when supplementary code-set characters are also
subject to conversion.
ebcdic Convert ASCII to EBCDIC. Conversion results cannot be
assured when supplementary code-set characters are also
subject to conversion.
ibm Slightly different map of ASCII to EBCDIC. Conversion
results cannot be assured when supplementary code-set
characters are also subject to conversion.
conv=block Convert newline-terminated ASCII records to fixed length.
unblock Convert fixed-length ASCII records to newline-terminated
records.
lcase Map alphabetics to lowercase. Multibyte characters are
not converted.
ucase Map alphabetics to uppercase. Multibyte characters are
not converted.
swab Swap every pair of bytes.
noerror Do not stop processing on an error (limit of five
consecutive errors).
notrunc Do not truncate a pre-existing output file.
sync Pad every input block to ibs. Pad with spaces if
conv=block or conv=unblock is specified, otherwise pad
with nulls.
..., ... several comma-separated conversions.
Where sizes are specified, a number of bytes is expected. A number can
end with k, b, or w to specify multiplication by 1024, 512, or 2,
respectively; a pair of numbers can be separated by x to indicate
multiplication.
cbs is used only if ascii, unblock, ebcdic, ibm, or block conversion is
specified. In the first two cases, cbs characters are copied into the
conversion buffer, any specified character mapping is done, trailing
blanks are trimmed, and a newline is added before sending the line to the
output. In the latter three cases, characters are read into the
conversion 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
This command reads an EBCDIC tape that is blocked ten 80-byte EBCDIC card
images per tape block into the ASCII file x:
dd if=/dev/rmt/0h of=x ibs=800 obs=8k cbs=80 conv=ascii,lcase
Note the use of raw magnetic tape. dd is especially suited to I/O on the
raw physical devices because it allows reading and writing in arbitrary
block sizes.
FILES
/usr/lib/locale/locale//LC_MESSAGES/uxcore.abi
language-specific message file (see LANG on environ(5))
SEE ALSO
cp(1).
DIAGNOSTICS
f++p records in(out)
numbers of full and partial blocks read(written)
NOTES
Do not use dd to copy files between filesystems having different block
sizes.
Using a blocked device to copy a file results in extra nulls being added
to the file to pad the final block to the block boundary.