From: Samuel Thibault <samuel.thibault@ens-lyon.org>
To: Jon <jg@jguk.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
linux-kernel@vger.kernel.org
Subject: Re: dd if=/dev/random of=data.bin bs=512 count=1
Date: Sat, 23 May 2009 21:20:08 +0200 [thread overview]
Message-ID: <20090523192008.GD10166@const.famille.thibault.fr> (raw)
In-Reply-To: <4A184ABB.1070902@jguk.org>
Jon, le Sat 23 May 2009 20:12:59 +0100, a écrit :
> KOSAKI Motohiro wrote:
> >>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.
>
> Is this a "feature" of /dev/random ?
It is, as opposed to urandom
> ..it does not seem very useful to have it able to block for so long.
The feature is about to wait for random data to be available, not only
pseudo-random data.
Samuel
next prev parent reply other threads:[~2009-05-23 19:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-17 15:22 dd if=/dev/random of=data.bin bs=512 count=1 Jon Grant
2009-05-17 16:01 ` KOSAKI Motohiro
2009-05-23 19:12 ` Jon
2009-05-23 19:20 ` Samuel Thibault [this message]
2009-05-23 19:38 ` Matt Mackall
2009-05-24 0:59 ` Bill Davidsen
2009-05-17 16:27 ` Bernd Eckenfels
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