On Sun, 15 Apr 2007, Akemi Yagi wrote:
> Date: Sun, 15 Apr 2007 06:37:18 -0700
> From: Akemi Yagi <amyagi@xxxxxxxxx>
> Reply-To: CentOS mailing list <centos@xxxxxxxxxx>
> To: CentOS mailing list <centos@xxxxxxxxxx>
> Subject: Re: Scripts to generate exact copy of
> CentOS-5.0-i386-bin-DVD.iso from CD images
>
> On 4/14/07, Wojtek.Pilorz <wpilorz@xxxxxx> wrote:
> > I am enclosing scripts and config files to generate exact copy
> > of CentOS 5.0 i386 installation DVD image, that is
> > CentOS-5.0-i386-bin-DVD.iso
> > if you have CD images for i386.
>
> I have 2 questions:
>
> (1) There is one thing that is puzzling to me. You present an
> alternative method that makes use of the existing
> CentOS-5.0-i386-bin-DVD.iso file. In this case (if you already have
> it), what is the purpose of running the scripts?
You prepare a DVD containing CD images and include scripts to generate DVD
image - so on one media you have, in a sense, both. Other than that, perhaps
not much reason.
>
> (2) The scripts are specific for CentOS 5.0 as you described. What
The method I use is general. The scripts should be made more general,
indeed. That would require a bit of planning.
> would it take to make them more generic?
> Is there any way to achieve
> the same without having to extract info from the original DVD?
Actually I did not have DVD image file. I had CD images on local fast mirror
which I could easily download.
I downloaded header of DVD image (part containing all directories definition)
and compared file length and timestamps.
With CentOS 5.0 it was easy - there were less than 50 files differing, most
of them needed to be downloaded (specific parts of DVD image).
The file resulting from the tree had SHA1 and MD5 checksums as advertised on
CentOS mirrors, so I could use it further in the process.
[
In case it did not match, I would use sha1 values for image segments from
bittorrent definition file to find out, where are the differences.
I have scripts that help me with that, but the process is not easy, unless
one is fluent with perl or similar tool.
]
Once I have destination DVD image, the process is quite straighforward, it
amounts to finding what files should be placed where in the image. To find out
I run the script which compares SHA1 values for 2K-aligned 2K chunks of
destination image with SHA1 values of 2K chunks for files supposed to be in the
image.
If anyone is interested in the tools I use, I can post then (all mine, all GPL).
>
> Akemi
Best regards,
Wojtek
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