From: Matthew Bloch <matthew@...>
Date: 2011-01-06T03:07:45+09:00
Subject: Re: Getting the actual size of a sparse file

On 05/01/11 17:27, Daniel Berger wrote:
>
>
> On Jan 5, 10:04 am, Ryan Davis<ryand-r...@zenspider.com>  wrote:
>> On Jan 5, 2011, at 08:37 , Daniel Berger wrote:
>>
>>> Hi,
>>
>>> How do you get the true size of a sparse file? Using /var/log/lastlog
>>> on Ubuntu as an example I see this with "ls -lh"
>>
>> If you're on ubuntu you should be able to provide extra options to du:
>>
>> http://en.wikipedia.org/wiki/Sparse_file
>
> True, but I'd like to use pure Ruby (not system calls) if possible, at
> least for *nix systems. Or will this require an extension?

dd if=/dev/zero bs=1 seek=100M count=0 of=out2

irb(main):011:0> stat=File.stat("out2")
=> #<File::Stat dev=0xfc0c, ino=160, mode=0100644, nlink=1, uid=1006, 
gid=1006, rdev=0x0, size=104857600, blksize=4096, blocks=0, atime=Wed 
Jan 05 18:02:08 +0000 2011, mtime=Wed Jan 05 18:02:08 +0000 2011, 
ctime=Wed Jan 05 18:02:08 +0000 2011>

irb(main):013:0> [stat.blocks*stat.blksize, stat.size]
=> [0, 104857600]

Gives you allocated size & filesystem size.

-- 
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