Jednou z nejlepších funkcionalit Debianu je jeho schopnost upgradování nainstalovaného systému z jedné stabilní verze na druhou: dist-upgrade — dobře známa fráze — velmi přispěla k dobré reputaci projektu. Včetně pár preventivních opatření, upgrading počítače zabere pouze pár minut nebo něco přes deset minut, v závislosti na rychlosti stahování z balíčkových úložišť.
Protože měl Debian dost času na to se vyvinout v mezidobí dvou stabilních vydání, měli by jste si přečíst poznámky vydání před tím, než budete upgradovat.
In this section, we will focus on upgrading a Stretch system to Buster. This is a major operation on a system; as such, it is never 100% risk-free, and should not be attempted before all important data has been backed up.
# deborphan | xargs aptitude --schedule-only remove
Now for the upgrading itself. First, you need to change the /etc/apt/sources.list
file to tell APT to get its packages from Buster instead of Stretch. If the file only contains references to Stable rather than explicit codenames, the change isn't even required, since Stable always refers to the latest released version of Debian. In both cases, the database of available packages must be refreshed (with the apt update
command or the refresh button in synaptic
).
Jakmile jsou tyto nové balíčkové zdroje zaregistrovány, měli by jste nejdříve udělat minimální upgrade pomocí apt upgrade
. Tím, že uděláme upgrade ve dvou krocích usnadňujeme práci nástrojům pro řízení balíčků a často se ujišťujeme, že máme jejich poslední verze, které mohou mít nashromážděné opravy chyb a zdokonalení vyžadované pro dokončení úplného upgradu distribuce.
Once this first upgrade is done, it is time to handle the upgrade itself, either with apt full-upgrade
, aptitude
, or synaptic
. You should carefully check the suggested actions before applying them: you might want to add suggested packages or deselect packages which are only recommended and known not to be useful. In any case, the front-end should come up with a scenario ending in a coherent and up-to-date Buster system. Then, all you need is to do is wait while the required packages are downloaded, answer the debconf questions and possibly those about locally modified configuration files, and sit back while APT does its magic.
6.7.2. Řešení problémů po upgradu
Navzdory nejlepší snaze správců Debianu, nejsou hlavní systémové upgrady vždy tak hladce probíhající, jak by jste si přáli. Nové verze softwarů nemusí být kompatabilní se svými předchůdci (jejich přednastavené chování nebo datový formát například, může být pozměněn). Také některé chyby mohly proklouznout navzdory testovací fázi, která vždy předchází vydání Debianu.
K předejití některým takovým problémům, můžete nainstalovat balíček apt-listchanges , který zobrazuje informace o možných problémech na začátku upgradu balíčku. Tato informace je sestavena správci balíčku a vložena do souborů /usr/share/doc/package/NEWS.Debian
pro blaho uživatelů. Přečtením těchto souborů (třeba prostřednictvím apt-listchanges) by vám mělo pomoci předejít nepříjemným překvapením.
You might sometimes find that the new version of a software doesn't work at all. This generally happens if the application isn't particularly popular and hasn't been tested enough; a last-minute update can also introduce regressions which are only found after the stable release. In both cases, the first thing to do is to have a look at the bug tracking system at
https://bugs.debian.org/package
, and check whether the problem has already been reported. If this is case it will be also listed before the upgrade begins, if you have
apt-listbugs installed. If it hasn't, you should report it yourself with
reportbug
. If it is already known, the bug report and the associated messages are usually an excellent source of information related to the bug:
v jiných případech mohli uživatelé nalézt, jak se problému vyhnout a sdílet tak svůj pohled na věc v odpovědích na hlášení.
a ještě v dalších případech, opravený balíček již mohl být připraven a zveřejněn svými správci.
Depending on the severity of the bug, a new version of the package may be prepared specifically for a new revision of the stable release. When this happens, the fixed package is made available in the
proposed-updates
section of the Debian mirrors (see
6.1.2.3 – „Navrhované aktualizace“). The corresponding entry can then be temporarily added to the
sources.list
file, and updated packages can be installed with
apt
or
aptitude
.
Sometimes the fixed package isn't available in this section yet because it is pending a validation by the Stable Release Managers. You can verify if that is the case on their web page. Packages listed there aren't available yet, but at least you know that the publication process is ongoing.
6.7.3. Cleaning Up after an Upgrade
APT usually ensures a clean upgrade, pulling in new and updated dependencies, or removing conflicting packages. But even being such a great tool, it cannot cover all tasks users and administrators will face after an upgrade, because they require a human decision.
6.7.3.1. Packages removed from the Debian Archive
Sometimes the Debian FTP Masters remove packages from the Debian archive, because they contain release critical bugs, were abandoned by their upstream author or their package maintainer, or simply reached their end of life. In this case a newer Debian release does not ship the package anymore. To find all packages, which do not have a package source, use the apt-show-versions
command:
$
apt-show-versions | grep "No available version"
A similar result can be achieved by aptitude search ~o
. If the packages found are not required anymore, they should be purged from the system, because they will not face any updates for critical or security related bugs anymore.
6.7.3.2. Dummy and Transitional Packages
Sometimes, it might be necessary for a package to get a new name. In this case often the old package is kept as an (almost) empty package, depending on the new one and installing only the mandatory files in
/usr/share/doc/package/
. Such packages are called "dummy" or "transitional" packages. If the package maintainer in charge also changed the section of this package to
oldlibs
, then tools like
aptitude
,
deboprhan
, or
debfoster
(see sidebar
ALTERNATIVA deborphan
a debfoster
) can pickup these packages to suggest their removal.
Unfortunately there is currently no foolproof way of making sure that these packages are automatically removed or picked by the tools mentioned above. One way to check if the system still has some of these packages installed, is to look through the package descriptions of installed packages and then check the results. Be careful not to schedule the results for automatic removal, because this method can lead to false positives:
$
dpkg -l | grep ^ii | grep -i -E "(transition|dummy)"
6.7.3.3. Old or Unused Configuration Files
If the upgrade was successful there might be some configuration file cruft, either from dpkg (see
5.2.3 – „Checksums, seznam souborů nastavení“), ucf or from removed packages. The latter can be
purged by using
apt autoremove --purge
. The configuration files, that were handled by
dpkg or
ucf during the upgrade process, have left some counterparts with a dedicated suffix (e.g.
.dpkg-dist
,
.dpkg-old
,
.ucf-old
). Using the
find
or
locate
command can help to track them down. If they are no longer of any use, they can be deleted.
6.7.3.4. Files not owned by any Package
The Debian policy enforces that packages don't leave files behind when they are purged. Violating this principle is a serious bug and you will rarely encounter it. If you do, report it; and if you are curious though, you can use the cruft or cruft-ng package to check your system for files not owned by any package.