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Subject: Re: dd if=/dev/random of=data.bin bs=512 count=1
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Jon Grant <jg@jguk.org>
Cc: linux-kernel@vger.kernel.org
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> Hello
>
> Issuing this command, I expected to get a file 4096 bytes in size.
> Could someone let me know if I have missed something..? Or is there a
> problem with using /dev/random this way?
>
> if I have a count=10 it hangs forever (several hours).
>
> Changing to use /dev/urandom and it generates the file ok.

you already have the answer. /dev/random might blocked, /dev/urandom doesn't.


> Please include my email address in replies,  as I'm not a member of this list.
>
> Best regards, Jon
>
> $ dd if=/dev/random of=data.bin bs=512 count=1
> 0+1 records in
> 0+1 records out
> 8 bytes (8 B) copied, 4.47366 s, 0.0 kB/s
>
> $ dd --version
> dd (coreutils) 6.10
>
> $ uname -a
> Linux ubuntu 2.6.28-11-generic #42-Ubuntu SMP Fri Apr 17 01:57:59 UTC
> 2009 i686 GNU/Linux
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