Questions about the dd command

Karl Larsen k5di at
Fri Feb 29 21:24:55 UTC 2008

elmo wrote:
> I've spent literally hours trying to find direct answers on the dozens 
> of websites that discuss 'dd'
> but the couldn't find what I wanted.
> A few questions about the ' dd ' command:
>   For example:     sudo dd if=/dev/sda2 of=/dev/sdb2 bs=1440
>   1. Which is preferrable;    execute the command from an installed
>        ubuntu (/dev/sda2) or from a ubuntu CD?
    There is no point to using dd from a CD-Rom. That is silly.

>   2. How do you  modify the example  to show the data as it is being 
> copied? 
>      Would this have a drastic effect on how long it takes to complete 
> the copy
>       compared to just watching a blinking cursor?
    There is no way I know to see what is happening.
>   3.  What effect on the does the ' bs = ' number have on
>       the time to complete the copy or the accuracy of the copy?  Is 
> there a
>       default number if the the bs=    is omitted from the command?
> 	If you do not use a bs= it uses the default which is dead slow. I use bs=10000 and it is much quicker.

    Suggest you read man dd where all these things come from.




	Karl F. Larsen, AKA K5DI
	Linux User
   PGP 4208 4D6E 595F 22B9 FF1C  ECB6 4A3C 2C54 FE23 53A7

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