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Re: [vox-tech] files with holes in them
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Re: [vox-tech] files with holes in them

  • Subject: Re: [vox-tech] files with holes in them
  • From: jdnewmil@dcn.davis.caMAPS.us
  • Date: Fri, 17 Nov 2000 20:23:21 -0800
  • References: Pine.LNX.4.21.0011172004580.6079-100000@belial.ucdavis.edu

On Fri, 17 Nov 2000, Peter Jay Salzman wrote:

> i was playing around with creating files with holes in them:
>       % ls -l holy_file
>       -rw-------    1 p        p        10000003 Nov 17 19:59 holy_file
>       % du -k holy_file
>       24      holy_file
> the program i wrote to generate this file looks more or less like:
>       if((fd = open("holy_file", O_WRONLY|O_CREAT)) < 0)
>               exit(0);
>       write(fd, string1, strlen(string1));
>       lseek(fd, 99999, SEEK_SET);
>       write(fd, string2, strlen(string2));
> ls gets its info from stat.  i did an strace on du, and it also calls stat.
> i'm curious about the discrepency in file size.  does anyone know why the
> two programs report different file sizes?

Because by design du looks at allocated disk space, and ls looks at the
recorded file size.  From "man stat", I gather the former comes from
st_blocks and the latter comes from st_size.

But you knew this already... or you wouldn't have been playing with holey
files... right?

Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnewmil@dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live Go...
Work:<JeffN@endecon.com>              Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...2k

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