Date: Wed, 24 Jun 2009 11:31:15 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Alexander Best <alexbestms@math.uni-muenster.de> Cc: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>, Julian Elischer <julian@elischer.org>, freebsd-hackers@freebsd.org Subject: Re: small usr.bin/find patch Message-ID: <4A420073.6060405@infracaninophile.co.uk> In-Reply-To: <permail-20090624094151f0889e8400007f8d-a_best01@message-id.uni-muenster.de> References: <permail-20090624094151f0889e8400007f8d-a_best01@message-id.uni-muenster.de>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig2E256E8A5CC0367E058D39F3 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Alexander Best wrote: > hmmm...but dd e.g. uses lowercase instead of upercase letters to indica= te > kilobyte, megabyte and so on. isn't there some unix/posix/whatever stan= dard > telling app developers what to use? Sure. The standard for scale-prefixes is defined by the Systeme Internationale as part of the definition of SI units: http://www.npl.co.uk/reference/measurement-units/si-prefixes/ Note that these are strictly powers-of-10^3 multipliers, and explicitly not the computing style powers-of-2^10 commonly used for file sizes or hard drive capacities, which should instead use the somewhat clunky Ki, Mi, Gi etc. forms: http://physics.nist.gov/cuu/Units/binary.html These binary prefixes are mandated by the IEC and approved by the IEEE amongst others. Not that many people use the binary prefixes appropriately, relying on context to disambiguate 1 MB =3D 1024 KB =3D 1,048,576 Bytes etc. Except= that (confusingly) as a measure of network bandwidth 10 Mb/s always was 10,000,000 b/s and never 10,485,760 b/s; a fact that has caught me out more than a few times. Making find(1) / dd(1) / etc. operate pedantically correctly with these scale-factor symbols would cause a certain degree of pain for little practical gain. Unless there was a broad consensus amongst all Unixoid OS providers, I can't see that change ever happening. Cheers, Matthew --=20 Dr Matthew J Seaman MA, D.Phil. Flat 3 7 Priory Courtyard PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate Kent, CT11 9PW, UK --------------enig2E256E8A5CC0367E058D39F3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.12 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkpCAHkACgkQ3jDkPpsZ+Vbk2QCfTy+bY7J+xLQqPLPuS13EyGqJ U/0AnicsyrN5dYfq6XqtKJJWpYOJWmmt =0BN+ -----END PGP SIGNATURE----- --------------enig2E256E8A5CC0367E058D39F3--
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