install, update, pkgs consistency

[Steve O'Hara-Smith]

On Wed, 26 Aug 2020 22:31:30 -0600
Gary Aitken <freebsd at dreamchaser.org> wrote:

> I'm confused about the synchronization between a sys install, sys update,
> and packages (as opposed to ports).
> 
> It was my understanding that packages are built to be consistent with the
> OS, so that once the OS version is installed, any "pkg install" is
> more-or-less guaranteed to be consistent and compatible with the OS and
> other packages being installed.  true?

	Essentially yes - FreeBSD maintains ABI compatibility throughout
the life of a major release (barring bugs and mistakes such as the DRM one
between 12.0 and 12.1) so packages are built to the major release ABI.

	The ports tree from which the packages are built is continuously
updated but quarterly snapshots are taken and used to make quarterly
package updates. You can choose to follow the quarterly snapshots or live
on the bleeding edge - by default the quarterly snapshots are what you get,
controlled by /etc/pkg/FreeBSD.conf.

> If I install a package shortly after installing the OS, then some months
> later delete the package and install it again, will the same version be
> installed (assuming I have not updated the system)?

	Probably not, you will get the version in the latest quarterly
snapshot.

> When the OS is upgraded, e.g. for security patches using freebsd-update,
> does the package collection remain unchanged, or is it updated as well?

	It is updated independently of the OS at quarterly intervals for
the snapshots and continuously for the latest.

> If I install packages, then some months later update the system
> (freebsd-update), could some of the previously installed packages
> no longer function properly?

	Only if you cross a major version boundary or there's a screwup in
maintaining ABI compatibility (those are very rare - I only recall one).

> If I install packages, then some months later update the system, then
> install more packages, could some of the new packages not function (or not
> install) because of incompatibilities with previously installed packages?

	The install will also perform any necessary updates.

> Why does /var/cache/pkg show multiple versions, some dated after the date
> of the installed system, if pkgs are supposed to be tied to the original
> sys install or update?

	Quarterly updates - 'nuff said ?

-- 
Steve O'Hara-Smith <steve at sohara.org>