DD(1L)DD(1L)NAME
dd - convert a file while copying it
SYNOPSIS
dd [--help] [--version] [if=file] [of=file] [ibs=bytes] [obs=bytes]
[bs=bytes] [cbs=bytes] [skip=blocks] [seek=blocks] [count=blocks]
[conv={ascii,ebcdic,ibm,block,unblock,lcase,ucase,swab,noerror,notrunc,
sync}]
DESCRIPTION
This manual page documents the GNU version of dd. dd copies a file
(from the standard input to the standard output, by default) with a
user-selectable blocksize, while optionally performing conversions on
it.
OPTIONS
Numbers can be followed by a multiplier:
b=512, c=1, k=1024, w=2, xm=number m
--help Print a usage message on standard output and exit successfully.
--version
Print version information on standard output then exit successâ
fully.
if=file
Read from file instead of the standard input.
of=file
Write to file instead of the standard output. Unless
conv=notrunc is given, truncate file to the size specified by
seek= (0 bytes if seek= is not given).
ibs=bytes
Read bytes bytes at a time.
obs=bytes
Write bytes bytes at a time.
bs=bytes
Read and write bytes bytes at atime. Override ibs and obs.
cbs=bytes
Convert bytes bytes at a time.
skip=blocks
Skip blocks ibs-sized blocks at start of input.
seek=blocks
Skip blocks obs-sized blocks at start of output.
count=blocks
Copy only blocks ibs-sized input blocks.
conv=conversion[,conversion...]
Convert the file as specified by the conversion arguments.
Conversions:
ascii Convert EBCDIC to ASCII.
ebcdic Convert ASCII to EBCDIC.
ibm Convert ASCII to alternate EBCDIC.
block Pad newline-terminated records to size of cbs, replacing
newline with trailing spaces.
unblock
Replace trailing spaces in cbs-sized block with newline.
lcase Change uppercase characters to lowercase.
ucase Change lowercase characters to uppercase.
swab Swap every pair of input bytes. Unlike the Unix dd, this
works when an odd number of bytes are read. If the input
file contains an odd number of bytes, the last byte is
simply copied (since there is nothing to swap it with).
noerror
Continue after read errors.
notrunc
Do not truncate the output file.
sync Pad every input block to size of ibs with trailing NULs.
FSF GNU File Utilities DD(1L)
