Re: "ls -h -l" returns 255GB, while "ls -l" returns 272 gigabytes

[Matthew Woehlke]

Jameson C. Burt wrote:
> Following are responses from "ls" on a file, partition.img,
> which is a partition image I created using "dd".
> While being created, as this file got large, 
> the target partition disappeared until I rebooted 
> (a Linux problem, surely, 
> and I mention this only for the full context of the following "ls" result).
> Upon rebooting, the resulting filesize listed with "ls" is inconsistent,
>    ls -h -l partition.img
>       -rw-r--r-- 1 root root 255G 2006-10-24 23:10 partition.img
>    ls  -l partition.img
>       -rw-r--r-- 1 root root 272751509504 2006-10-24 23:10 partition.img
> Presuming the filesize to be 272,751,509,504, 
> then  "ls -h -l" should return
>    272G  not  255G

Nope, actually if ls is doing anything wrong, it is that it is rounding 
(approx) 254.02G up to 255G.

272751509504 / (1024^3) = 254.019638...G

> Perl affirms (although it might use the same underlying OS command) the 272G 
> value,
>    perl -e  'print -s "partition.img", "\n"'
>       272751509504
> One would expect that both  "ls -h -l"  and  "ls -l"  use the same
> underlying number, merely printing diffently,
> so I'm surprised to see different numbers with and without "-h".
>
> Possibly, the value 255G represents an acutal filesize of 256GB,
> a possible limit from some source, in which case 272G could be wrong.
>
>
> Following are correct responses from "ls" on a file I created of exactly 2.2 GB
> (dd  if=/dev/zero  of=zero-test  bs=1000  count=2200000),
>    ls -l  zero-test
>       -rw-r--r-- 1 root root 2200000000 2006-10-25 09:51 zero-test
>    ls -h -l  zero-test
>       -rw-r--r-- 1 root root 2.1G 2006-10-25 09:51 zero-test
> These results are consistent, although one might prefer "ls -h -l"  to
> give 2.2G rather than 2.1G.

2200000000 / (1024^3) = 2.0489...G, or 2.1G (again, explicitly rounding up).

Hint:

1 kB = 1024 bytes
1 MB = 1024 kB
1 GB = 1024 kB

Next time try reading the man page, especially the option '--si' right 
under '-h'.

--
Matthew
When on POSIX, do as POSIX mandates.