|
I ask the following questions not to troubleshoot a poblem I am
having but rather to know whats going on behind the scenes with
package management. I know that apt is not part of dpkg. Hope nobody
minds me bringing it into the discussion. I have read up on Debian Package Management as much as I can at
this stage.
Thanks to the Debian Policy manual, I understand how the remote
repositories are structured
and how sources.list is used to consult the repositories to
locate updates.
I understand what is contained in a package file and that it
has everything required
to install AND remove a package. I have delved into the
/var/lib/dpkg directory and
I understand that the info sub directory contains the scripts
and information needed to remove a package.
So far so good.
My confusion begins with these files:
/var/cache/apt/pkgcache.bin
/var/lib/dpkg/status
/var/lib/dpkg/available
I have observed that it doesn't really matter if pkgcache.bin
doesn't exist because apt-get update
quickly rebuilds it to its full size. Does it rebuild it by
trawling through the repository again?
What is it used for/what does it contain? It would seem to be
redundant based on what the next two files
are used for.
In the /var/lib/dpkg directory there are two important files: available
and status.
status is the most important one as nothing will work if it is
lost or corrupted.
Both contain the standard control information on each package.
status,
on my machine, only contains descriptions of packages that are
actually installed.
This seems to be the definitive source for determining that a
package is installed.
If you remove a package it is removed from the status file. I
presume apt-get
relies on status to tell if a package is already installed?
What is "available" for and how is it built up?
My understanding is that dpkg does not have the concept of a
configured remote repository.
So in the world of dpkg, what does it mean to say that a
package is "available"?
Ciaran
|