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DD

Posted On 2007-04-27 by FortyPoundHead
Keywords: Command Reference
Tags: Linux Commandline Linux
Views: 1583


Dump Data - convert and copy a file (use for RAW storage), create a boot floppy.

SYNTAX
dd [OPTION]...

DESCRIPTION
The numeric-valued options below (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 (*note Block size::).

`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''
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.Example:
dd can be used to create a boot floppy:

dd if=boot.img of=/dev/fd0 bs=1440

where

if = the input file or device
of = the output file or device
bs = the block size for both input and output files


About the Author

FortyPoundHead has posted a total of 1974 articles.

 


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