Re: Enhancements request – Accuracy, Documentation, Conventions, Basic units of measure

[L A Walsh]

Ricky Tigg wrote:
> –Issue reported first at bugzilla.red hat 1582165
> <https://bugzilla.redhat.com/show_bug.cgi?id=1582165>–
>
> OS :Fedora
> Version-Release number of component: coreutils.x86_64 8.29-6.fc28 @updates
>
> 1. Accuracy
>
> Actual results: In terminal, outputs resulting from the execution of
> command:
> – 'df -h' are specified at best with one digit accuracy.
>
> Enhancement: An accuracy with two digits (model 0.00 M) would be
> appropriate.
>   
----
   When describing integral values, fractional values like
decimal digits to the right of the period are *inherently* inaccurate
because you are using decimal prefixes on binary units.

   It would be like cooks using deci-cups or deci-pounds --
the really shouldn't be intermixed.  Having more digits to
the right of the the decimal place doesn't make a lot of sense.
'du' uses 1024 byte blocks by default.  The minimum sector
size is 512.  So capacities in sectors can always be described
using, at most, 1 decimal point a size of 3.5MB =
(3*1024+512)*1024 Bytes, exactly.  You can't get more accurate.
The same value in decimal with 2 digits would be 3.67 --which
is less accurate than the current display.

> 2. Documentation
>
> Actual results: Df tool displays sizes associated to data storage observing
> the notation (k, M, G, ...) while obviously outputs resulting from 'df'
> tends to indicate that actually, by default sizes associated to data
> storage are specified by ...
reading from the man page, which specifies 1024B units.  Thus

> 3. Conventions
>
> Actual results: Convention used regarding the signs '%'...
> Furthermore readability of '0 %' is superior to '0%'.
>   
----
   Unix computers split fields based on white space.  If you
use '10 %' or '10 MB' will be split off from the unit.  I can't
see why numbers missing their units would be superior for any
usage.

> Actual results: Basic units of measure are missing since only metric
> prefixes are displayed.
>   
----
   Terminals are only 80 columns wide for the most part. 
Width is still limited.  Adding extra units when they can be
documented externally is similar to the computer process known
as removing a loop-invariant.  The 'Byte' is invariant.  We
aren't mixing units.  So it is more efficient to document that
elsewhere and only put the changing values (number+suffix)
in the visual field.  Padding the field with invariant material
is documented to lead to slower comprehension (by humans). 

   In a similar way, justifying text, or using a monospace
font results in slower comprehension than using a variable width
font due to the way humans recognize letters and words.  The
lack of important width info from the letters adds extra,
invariant spacing (as does text justification) with slows down
reading comprehension.

   So...adding repetitive stuff that isn't needed -- not so good.

*cheers*
-Linda W.