[vox-tech] Debian Unstable - apt strangeness

[Rick Moen]

Quoting David Hummel (dhml at comcast.net):

> dpkg must know about available packages since:
> 
> $ dpkg -l package-name-pattern
> 
> lists available packages (apparently from /var/lib/dpkg/available)
> regardless of whether they're installed.

Perhaps I was a bit unclear:  dpkg knows only about what's in
/var/lib/dpkg/status.  It can glean information about uninstalled
packages from that file only because apt puts that data there.

The wording of Peter's post suggested he might be unaware of the
segmentation of roles between the two programs.  So, I detailed the
difference:  apt fetches but doesn't install; dpkg installs but doesn't
fetch.  (apt must therefore invoke dpkg to complete package
installation.)  Clearer?

I was extremely vaguely aware that /var/lib/dpkg/status includes stanzas
about uninstalled packages, but that fact tends to slip my mind because
I don't use it:   The useful way to use "dpkg -l ..." is without globs,
which, for reasons I haven't looked into, omits uninstalled packages
from the return values.  Which is what I said before.

> Therefore, it's a bit misleading that dpkg -l with no
> package-name-pattern only lists installed packages.
> 
> So how is /var/lib/dpkg/available generated if not from apt?

I'm utterly mystified as to how you could think I said otherwise.

apt pulls down (among other things) *Packages files from the various
sources into /var/lib/apt/lists, then merges them to form a single
/var/lib/dpkg/available file.  _Of course_ it's generated by apt.