Re: Discussion about why GNU/Linux system upgrades cause old programs to break

On Wed, Aug 12, 2026 at 10:17:34AM +0200, Dr. Arne Babenhauserheide wrote:
> Richard Stallman <[email protected]> writes:
> 
> > Does it mean sysadmins, after the upgrade, think about which old
> > libraries to delete?
> >
> > Or is it something automatic that happens as part of an upgrade?
> 
> When the libraries are installed transitively as part of an application
> install, then after an update, distribution package managers usually
> check which of these libraries are no longer needed and suggest removing
> them.
> 
> To avoid that can install a library explicitly
> (e.g. via =apt-get install libpng-dev= for the dev headers of libpng)
> then after an update, libpng-dev stays available.

Typically there is more to that. Usually, different versions of a library
are not co-installable in Debian. The newer version [1] replaces the older
(there are exceptions, but that means having different packages for
different versions of the library).

Usually, whithin Debian stable, versions don't change (that's what the
"stable" means). Package maintainers try to back-port important (security,
bug fix) patches if necessary.

A self compiled package thus can well "fall back" when upgrading to a
new Debian version, e.g. if a dependency is removed (because it is
unmaintained, or because it has unsolved issues preventing it to be
included in the new version.

Cheers

[1] "Version" is sloppy here. In general it's "major version", i.e.
   whatever is backward compatible, so that all the library's clients
   are happy with the change.

-- 
tomás

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