GNU bug report logs - #8320
df -BT: rounding error?

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Voelker, Bernhard" <bernhard.voelker <at> siemens-enterprise.com>
To: "bug-coreutils <at> gnu.org" <bug-coreutils <at> gnu.org>
Subject: df -BT: rounding error?
Date: Tue, 22 Mar 2011 16:47:41 +0100

Running `df -B...` with a SIZE which is greater than the total disk space
returns the same value in the 'Used' and 'Available' column - see example
below with T, P and E:

$ for f in 1 K M G T P E Z Y ; do ( set -x && df -B$f . ) ; done
+ df -B1 .
Filesystem           1B-blocks      Used Available Use% Mounted on
D:                   596087726080 100868861952 495218864128  17% /cygdrive/d
+ df -BK .
Filesystem           1K-blocks      Used Available Use% Mounted on
D:                   582116920K 98504748K 483612172K  17% /cygdrive/d
+ df -BM .
Filesystem           1M-blocks      Used Available Use% Mounted on
D:                     568474M    96197M   472278M  17% /cygdrive/d
+ df -BG .
Filesystem           1G-blocks      Used Available Use% Mounted on
D:                        556G       94G      462G  17% /cygdrive/d
+ df -BT .
Filesystem           1T-blocks      Used Available Use% Mounted on
D:                          1T        1T        1T  17% /cygdrive/d
+ df -BP .
Filesystem           1P-blocks      Used Available Use% Mounted on
D:                          1P        1P        1P  17% /cygdrive/d
+ df -BE .
Filesystem           1E-blocks      Used Available Use% Mounted on
D:                          1E        1E        1E  17% /cygdrive/d
+ df -BZ .
df: -B argument `Z' too large
+ df -BY .
df: -B argument `Y' too large

Apart from saying that 1[TPE] is still available ... shouldn't it return
0[TPE] for the "Used" column, as rounding a value of 17% should lead to
zero (mathematically)?

BTW: why are `Z' and `Y' "too large"?

$ df --version
df (GNU coreutils) 8.10
Packaged by Cygwin (8.10-1)

It's on a 32-bit XP.

Have a nice day,
Berny

Message #8 received at 8320 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: "Voelker, Bernhard" <bernhard.voelker <at> siemens-enterprise.com>
Cc: 8320 <at> debbugs.gnu.org
Subject: Re: bug#8320: df -BT: rounding error?
Date: Tue, 22 Mar 2011 09:47:42 -0700

On 03/22/2011 08:47 AM, Voelker, Bernhard wrote:
> shouldn't it return
> 0[TPE] for the "Used" column, as rounding a value of 17% should lead to
> zero (mathematically)?

df always rounds up, rather than to nearest.
I vaguely recall that POSIX specifies that, for -k.

> BTW: why are `Z' and `Y' "too large"?

They don't fit in 64 bits.

Message #11 received at 8320 <at> debbugs.gnu.org (full text, mbox):

From: "Voelker, Bernhard" <bernhard.voelker <at> siemens-enterprise.com>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: "8320 <at> debbugs.gnu.org" <8320 <at> debbugs.gnu.org>
Subject: RE: bug#8320: df -BT: rounding error?
Date: Tue, 22 Mar 2011 18:21:17 +0100

Paul Eggert wrote:

> On 03/22/2011 08:47 AM, Voelker, Bernhard wrote:
>> BTW: why are `Z' and `Y' "too large"?
>
>They don't fit in 64 bits.

wow, I wasn't aware that there are already 128-bit systems!

Bye,
Berny

Message #14 received at 8320 <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: "Voelker\, Bernhard" <bernhard.voelker <at> siemens-enterprise.com>
Cc: Paul Eggert <eggert <at> cs.ucla.edu>,
	"8320 <at> debbugs.gnu.org" <8320 <at> debbugs.gnu.org>
Subject: Re: bug#8320: df -BT: rounding error?
Date: Sun, 17 Apr 2011 08:39:53 +0200

tags 8320 notabug
close 8320
thanks

Voelker, Bernhard wrote:
> Paul Eggert wrote:
>> On 03/22/2011 08:47 AM, Voelker, Bernhard wrote:
>>> BTW: why are `Z' and `Y' "too large"?
>>
>>They don't fit in 64 bits.
>
> wow, I wasn't aware that there are already 128-bit systems!

Hi Voelker,
It looks like this is resolved, and is not a bug,
so I've closed the issue.  You're welcome to reopen it
if you're not satisfied with that.

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