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Re: [PLUG] Linux Bootable CD
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On Fri, 22 Mar 2002, Bill Jonas wrote:
>
> On Fri, Mar 22, 2002 at 12:27:29PM -0500, Doug Crompton wrote:
> > I am not sure. Does dd from a device without limits copy the entire
> > medium?
>
> Yes. It reads until it reaches EOF, which means there's no more data.
> It would be the same as doing "cat /dev/cdrom >output-file.iso" or "cp
> /dev/cdrom output-file.iso". The nice thing about dd is that you can
> specify a block size to speed up the transfer, ie, bs=1M, so that you
> have fewer read/write operations going on (transfer a meg at a time
> versus the default block size for the device).
>
> You may be thinking of the use of dd to create a file of a certain size,
> dd'ing from /dev/zero. In this case, bs and count are needed since
> /dev/zero *never* returns EOF and dd will keep going until your device
> is full, failing with an error message like "dd: writing `filename': No
> space left on device".
>
> Bill Jonas * bill@billjonas.com * http://www.billjonas.com/
>
> Developer/SysAdmin for hire! See http://www.billjonas.com/resume.html
>
No what I meant was why make an ISO file of 650megs when you only need a
few megs for a boot CD. Thus the bs and count in dd. mkisfs also only
makes a iso the size needed for the data you specify.
Doug
****************************
* Doug Crompton *
* Richboro, PA 18954 *
* 215-431-6307 *
* *
* doug@crompton.com *
* wa3dsp@wa3dsp.ampr.org *
* http://www.crompton.com *
****************************
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