Re: how do I make a jigdo

[Richard Atterer <richard@2006.atterer.net>]

Hi Carl,

some documentation about creating .jigdo files is available in the 
jigdo-file manpage. In particular, to get started you might want to have a 
look at the examples section - see 
<http://atterer.net/jigdo/jigdo-file.html#EXAMPLES>

On Mon, Mar 20, 2006 at 12:09:03PM -0600, Carl Karsten wrote:
> Part of my current "project" is to learn about jigdo, so even if it isn't 
> a good fit, I want to use it anyway just to get a grip on it.
> 
> Here is my current project: Josh made an v1.iso, I downloaded the image.  
> Josh made some changes and made v2.iso.  the source files can be put on a 
> web server.
> 
> So currently there is /v1, /v2, v1.iso and v2.iso on the "server" side 
> and /v1 and v1.iso on the client side.
> 
> I have remote access to Josh's box, I told Josh I would figure this out.

First, for jigdo's purposes, there's only one image to worry about: v2.iso! 
When you actually try to download v2.iso using jigdo-lite, you can supply 
the contents of v1.iso as "files to scan" and jigdo-lite will figure out 
automatically which parts to reuse.

So, to make v2.iso available via jigdo, the first example from the manpage 
examples can be adapted. I'll assume that /v2 is available as 
http://josh.org/v2 :-)

Logged in on Josh's machine, execute "jigdo-file make-template" with the 
following arguments:

--image=v2.iso  to supply the input filename. jigdo-file will automatically 
deduce the output filenames "v2.jigdo" and "v2.template" from that.

/v2//  Spelled exactly like this with a double slash, this tells jigdo-file 
to 1) scan through /v2 for files which might be contained in v2.iso, and 2) 
if such a file is found, "cut off" the pathname at the double slash. Try 
a different placement of the // (e.g. /longer/path//to/v2) to see the 
effect on the contents of the output .jigdo file.

--label Josh=/v2  assigns the name "Josh" to the data beneath /v2. If this 
were left out, the boring default name "A" would be used.

--uri Josh=http://josh.org/v2/  assigns the URL to the name "Josh". The 
boring default output in the .jigdo file would be a file:// URL, which of 
course wouldn't work for a remote download.

Instead of using --label and --uri, you could also edit the .jigdo file 
manually after generation.

While playing around with jigdo-file, -0 and --force might be handy. -0 
turns off compression, which will make jigdo-file faster, and --force 
forces overwriting of output files which already exist.

Furthermore, throw in a --cache=~/jigdo.db switch to cache file md5sums. 
This will speed things up a lot after the first run of jigdo-file.

Cheers,

  Richard

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