Messages in this thread | | | Subject | Re: dd if=/dev/random of=data.bin bs=512 count=1 | From | Matt Mackall <> | Date | Sat, 23 May 2009 14:38:07 -0500 |
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On Sat, 2009-05-23 at 20:12 +0100, Jon wrote: > Hello KOSAKI, > > Thank you for your reply. > > KOSAKI Motohiro wrote: > >> 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. > > Is this a "feature" of /dev/random ? ..it does not seem very useful to > have it able to block for so long.
Yes. The theory is that it will be secure even in the event of a catastrophic failure of the cryptographic compression function. But don't worry about that; use /dev/urandom.
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