dd
Convert and copy a file, write disk headers, boot records, create a boot
floppy. dd can make an exact clone of an (unmounted) disk, this will include
all blank space so the output destination must be at least as large as the
input.
Syntax
dd [*Options*]
Key
if=*FILE*
Input file : Read from FILE instead of standard input.
of=*FILE*
Output file : Write to FILE instead of standard output. Unless
`conv=notrunc'
is given, `dd' truncates FILE to zero bytes (or the size specified
with `seek=').
ibs=*BYTES*
Read BYTES bytes at a time.
obs=*BYTES*
Write BYTES bytes at a time.
bs=*BYTES*
Block size, both read and write *BYTES* bytes at a time. This
overrides `ibs'
and `obs'.
cbs=*BYTES*
Convert BYTES bytes at a time.
skip=*BLOCKS*
Skip BLOCKS `ibs'-byte blocks in the input file before copying.
seek=*BLOCKS*
Skip BLOCKS `obs'-byte blocks in the output file before copying.
count=*BLOCKS*
Copy BLOCKS `ibs'-byte blocks from the input file, instead of
everything until the end of the file.
conv=*CONVERSION*[,*CONVERSION*]...
Convert the file as specified by the CONVERSION argument(s).
(No spaces around any comma)
Conversions:
`ascii' Convert EBCDIC to ASCII.
`ebcdic' Convert ASCII to EBCDIC.
`ibm' Convert ASCII to alternate EBCDIC.
`block' For each line in the input, output `cbs' bytes, replacing the
input newline with a space and padding with spaces as
necessary.
`unblock' Replace trailing spaces in each `cbs'-sized input block
with a newline.
`lcase' Change uppercase letters to lowercase.
`ucase' Change lowercase letters to uppercase.
`swab' Swap every pair of input bytes. GNU `dd', unlike others,
works when an odd number of bytes are read--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 zero bytes.
The numeric-valued options (BYTES and BLOCKS) can be followed by a
multiplier: `b'=512, `c'=1, `w'=2, `xM'=M, or any of the standard block size
suffixes like `k'=1024.
*Examples:*
Clone one hard drive onto another
$ dd if=/dev/sda of=/dev/sdb
Clone a hard drive to an image file
$ dd if=/dev/hda of=/image.img
Clone a hard drive to a zipped image file in 100Mb blocks
$ dd if=/dev/hda bs=100M | gzip -c > /image.img
Create a boot floppy:
$ dd if=boot.img of=/dev/fd0 bs=1440
*"Success isn't something you chase. It's something you have to put forth
the effort for constantly. Then maybe it'll come when you least expect it.
Most people don't understand that" - Michael Jordan *
*Related*:
CodeCoffee.com <http://www.codecoffee.com/tipsforlinux/articles/036.html> -
dd examples
cp <http://ss64.com/bash/cp.html> - Copy one or more files to another
location
ddrescue <http://ss64.com/bash/ddrescue.html> - Data recovery tool
install <http://ss64.com/bash/install.html> - Copy files and set attributes
mtools <http://ss64.com/bash/mtools.html> - Manipulate MS-DOS files
sum <http://ss64.com/bash/sum.html> - Print a checksum for a file
Equivalent Windows command: FSUTIL <http://ss64.com/nt/fsutil.html> file
setzerodata
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