On Fri, 20 Mar 2009 12:57 +1100, "Nathan Kroenert" <Nathan.Kroenert at Sun.COM> wrote: > Further to Richard and Malcolm's discussion: > > When you set bs=XX in dd, you are actually setting in effect: > ibs (input block size) > and > obs (output block size)
also one thing to note that I didn't realise until I was poring over the man page trying to work out this issue - the count=n field specifies the number of _input_ blocks dd will read, so if ibs and obs are different this may cause one to trip up ... :) > Something else interesting to note is that we typically specify a block > size for the sake of reducing the number of I/O's required to do the > operation. In the case of urandom, it would likely feed me stuff at > exactly the same speed, regardless of the block size, (entropy > requirements and all that) so I did not specify it. see, I thought of that, but as the advertised 'feature' of /dev/urandom is that it _doesn't_ rely on entropy (or not nearly so much as /dev/random), I thought this would work ... except it's probably been set this way for consistency between the two devices ... Regards, Malcolm -- Malcolm Herbert This brain intentionally mjch at mjch.net left blank
