THE DD COMMAND


This is one of the more complex Linux commands and actually not really suited for new Linux users. But still I would like to give you a little taste of it.

The dd command copies an amount of data block by block. The most basic syntax is:

( Where if=xxxxx is the source, of=yyyyy is the target and bs= both read and write zzzzz bytes at a time )
But as you might have guessed, the dd command it is much more than that, it can optionally convert data ( ASCII to EBCDIC ), skip blocks, continue after read errors, change uppercase letters to lowercase, etc, etc. ( type "info dd" in a terminal to get the full list of options )

I will now give you a few examples of what dd can do, but I do urge you to have a look at the links posted below to get more detailed information before you really start experimenting with the dd command.




Copy a hard disk partition to another hard disk:

Cloning an entire hard disk:

Copy a disk partition to a file on a different partition. ( Do not copy a partition to the same partition ! ):

Restore a disk partition from an image file:

Copy MBR only of a hard drive:

Reverse:

Wipe a hard drive of all data ( you would want to boot from a cd to do this ):

Make an iso image of a CD:

( CD sectors are 2048 bytes, so this copies sector for sector. )




Copy a floppy disk:

You can back up your MBR ( including partition table ):

Put this on a floppy you make with:

Boot from the floppy and restore the MBR:

Again, I urge you to be very careful with the DD command . . . switching if= with of= can have catastrophic results.



An extensive how-to of the dd command can be found here: Learn The DD Command   Please read it before you start typing "dd" !!
Maybe also read: Codecoffee



Bruno



-- Apr 22 2007 --