small du(1) question

[Alexander Best]

On Wed Oct 19 11, Alexander Best wrote:
> On Wed Oct 19 11, Chuck Swiger wrote:
> > On Oct 19, 2011, at 12:34 PM, Alexander Best wrote:
> > > the du(1) man page states the following:
> > > 
> > > "
> > >     -B blocksize
> > >             Calculate block counts in blocksize byte blocks.  This is differ-
> > >             ent from the -k, -m options or setting BLOCKSIZE and gives an
> > >             estimate of how much space the examined file hierarchy would
> > >             require on a filesystem with the given blocksize.  Unless in -A
> > >             mode, blocksize is rounded up to the next multiple of 512.
> > > "
> > > 
> > > is this a doc bug, or does du(1) really always assume that every filesystem's
> > > blocksize == 512?
> > 
> > The default blocksize is 512 bytes.
> > 
> > The -B option flag lets you tell du to assume a different filesystem blocksize.
> 
> so when running freebsd on a hdd with a blocksize of 4k, a simple 'du -h' will
> always display incorrect results, unless '-B 4096' was also specified? isn't
> there a way to automatically query the blocksize of the underlying device,
> instead of always asuming the blocksize is 512 byte?

...also: since -A is supposed to take the actual file size into account and not
the blocksize of the underlying filesystem, shouldn't the output of
'du -A -B4096' and 'du -A' be the same? just tested this on freebsd 7 and
freebsd 10 and the outputs differ.

cheers.
alex

> 
> cheers.
> alex
> 
> > 
> > Regards,
> > -- 
> > -Chuck
> >