Re: An INCOMPLETE solution - was [Re: Where is data stored when Synaptic scans DVDs?]
On Thu 23 Mar 2017 at 11:29:38 (+0000), Brian wrote:
> On Thu 23 Mar 2017 at 10:12:57 +0000, Darac Marjal wrote:
>
> > On Wed, Mar 22, 2017 at 08:08:28PM -0500, Richard Owlett wrote:
> > >On 03/17/2017 08:47 AM, Richard Owlett wrote:
> > >>As I have limited bandwidth, I install from DVDs.
> > >>Also I frequently experiment with various options by doing a fresh
> > >>install to a different partition.
> > >>It is annoying to keep re-scanning a set of 13 DVDs.
> > >>Where is the information stored?
> > >>/etc/apt/sources.list is obvious, but where is the data about contents
> > >>of each DVD stored?
> > >>TIA
> > >
> > >It had been suggested that all the needed information might be in
> > >/etc/apt/sources.list
> > > PLUS
> > >the /var/lib/apt directory
> > >
> > >It ain't :{
> >
> > Looking at the source, apt-cdrom does a bunch of checks and then calls into
> > pkgCdrom::Add()[1]. That does some more checks and then the interesting
> > stuff seems to start around line 746.
> >
> > The Configuration Database (TODO: Find where this is stored... Ah, I *think*
> > that's the /var/lib/apt/cdroms.list mentioned earlier) is checked for
> > existance of the CD and updated, if necessary. The next interesting part is
> > at line 838 where the packages are copied. This seems to happen in
> > IndexCopy::CopyPackages()[2] which, at line 97, creates a file in
> > /var/cache/apt/archives/partial/ containing the contents of the cdrom.
> >
> > [1] http://sources.debian.net/src/apt/1.4~rc2/apt-pkg/cdrom.cc/
> > [2] http://sources.debian.net/src/apt/1.4~rc2/apt-pkg/indexcopy.cc/
> >
> >
> > So, in summary, I think you need /etc/apt/sources.list, /var/lib/apt *AND*
> > /var/cache/apt/archives.
>
> Suppose /var/cache/apt/archives is empty because 'apt-get clean' has
> been run. What then?
Good point. I noticed that the two .bin files in /var/cache/apt/ that
https://lists.debian.org/debian-user/2017/03/msg00722.html
mentioned, come and go with apt-get update and clean respectively.
I had overlooked how ephemeral they are. They're built from scratch at
the "Reading package lists... Done" line after the Fetched line.
If your only sources are the DVDs then I can't see a problem with just
adding those files (or whatever the names are of any files that
appear—they could differ with apt-cdrom) to your list of files you
(OP) share between systems. It's tricky to check what's actually
in them as they're binary databases (what I called "hidden"
information previously).
Cheers,
David.
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