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Rozdział 6. Konserwacja i aktualizacje: Narzędzia APT

6.1. Wypełnianie pliku sources.list
6.1.1. Składnia
6.1.2. Repozytoria dla Stabilnych Użytkowników
6.1.3. Repozytoria dla użytkowników Testowej/Niestabilnej
6.1.4. Using Alternate Mirrors
6.1.5. Non-Official Resources: mentors.debian.net
6.1.6. Buforujący Pośrednik dla Pakietów Debiana
6.2. aptitude, apt-get, and apt Commands
6.2.1. Inicjalizacja
6.2.2. Instalacja i Usuwanie
6.2.3. Uaktualnienie systemu
6.2.4. Opcje konfiguracyjne
6.2.5. Zarządzanie Priorytetami Pakietów
6.2.6. Praca z Kilkoma Dystrybucjami
6.2.7. Śledzenie Automatycznie Zainstalowanych Pakietów
6.2.8. APT Patterns
6.3. Komenda apt-cache
6.3.1. The apt-cache policy Command
6.4. The apt-file Command
6.5. Interfejsy: aptitude, synaptic
6.5.1. aptitude
6.5.2. synaptic
6.6. Sprawdzanie Autentyczności Pakietów
6.7. Uaktualnienie z Jednej Stabilnej Dystrybucji do Następnej
6.7.1. Zalecana Procedura
6.7.2. Obsługa Problemów po Uaktualnieniu
6.7.3. Cleaning Up after an Upgrade
6.8. Utrzymywanie Aktualności Systemu
6.9. Automatyczne Uaktualnienia
6.9.1. Konfigurowanie dpkg
6.9.2. Konfigurowanie APTa
6.9.3. Konfigurowanie debconf
6.9.4. Obsługa Interakcji Linii Komend
6.9.5. Cudowne Połączenie
6.10. Wyszukiwanie Pakietów
What makes Debian so popular with administrators is how easily software can be installed and how easily the whole system can be updated. This unique advantage is largely due to the APT program, which Falcot Corp administrators studied with enthusiasm.
APT is the abbreviation for Advanced Packaging Tool. What makes this program “advanced” is its approach to packages. It doesn't simply evaluate them individually, but it considers them as a whole and produces the best possible combination of packages depending on what is available and compatible according to dependencies.
APT needs to be given a “list of package sources (repositories)”: the file /etc/apt/sources.list will list the different repositories that publish Debian packages. APT will then import the list of packages published by each of these sources. This operation is achieved by downloading Packages.xz files or a variant such as Packages.gz or .bz2 (using a different compression method) in case of a source of binary packages and by analyzing their contents. In case of a source of source packages, APT downloads Sources.xz files or a variant using a different compression method. When an old copy of these files is already present, APT can update it by only downloading the differences (see sidebar TIP Incremental updates).

6.1. Wypełnianie pliku sources.list

6.1.1. Składnia

Each active line in the /etc/apt/sources.list file represents a package source (repository) and is made of at least three parts separated by spaces. For a complete description of the file format and the accepted entry compositions see sources.list(5).

Przykład 6.1. Example entry format in /etc/apt/sources.list

deb url distribution component1 component2 component3 [..] componentX
deb-src url distribution component1 component2 component3 [..] componentX
Pierwsze pole określa rodzaj źródła:
deb
package source (repository) of binary packages
deb-src
package source (repository) of source packages
The second field gives the base URL of the source. Combined with the filenames listed in the Packages.xz files, it must give a full and valid URL. This can consist in a Debian mirror or in any other package archive set up by a third party. The URL can start with file:// to indicate a local source installed in the system's file hierarchy, with http:// or https:// to indicate a source accessible from a web server, or with ftp:// or ftps:// for a source available on an FTP server. The URL can also start with cdrom: for CD-ROM/DVD/Blu-ray disc based installations, although this is less frequent, since network-based installation methods are eventually more common. More methods like ssh:// or tor+http(s):// are supported and are either described in sources.list(5) or their respective apt-transport-method package documentation.
The syntax of the last field depends on the structure of the repository. In the simplest case, you can simply indicate a subdirectory (with a required trailing slash) of the desired source. This is often a simple “./” which refers to the absence of a subdirectory. The packages are then directly at the specified URL. But in the most common case, the repositories will be structured like a Debian mirror, with multiple distributions, each having multiple components. In those cases, name the chosen distribution by its “codename” — see the list in sidebar SPOŁECZNOŚĆ Bruce Perens, lider kontrowersyjny — or by the corresponding “suite” (oldoldstable, oldstable, stable, testing, unstable) and then the components to enable. A typical Debian mirror provides the components main, contrib, and non-free.
The cdrom entries describe the CD/DVD-ROMs you have. Contrary to other entries, a CD-ROM is not always available since it has to be inserted into the drive and since only one disc can be read at a time. For those reasons, these sources are managed in a slightly different way, and need to be added with the apt-cdrom program, usually executed with the add parameter. The latter will then request the disc to be inserted in the drive and will browse its contents looking for Packages files. It will use these files to update its database of available packages (this operation is usually done by the apt update command). From then on, APT can require the disc to be inserted if it needs one of its packages.

6.1.2. Repozytoria dla Stabilnych Użytkowników

Poniżej jest standardowy plik sources.list dla systemu działającego pod kontrolą Stabilnej wersji Debiana:

Przykład 6.2. plik /etc/apt/sources.list dla użytkowników Stabilnego Debiana

# Security updates
deb http://security.debian.org/ bullseye-security main contrib non-free
deb-src http://security.debian.org/ bullseye-security main contrib non-free

## Debian mirror

# Base repository
deb https://deb.debian.org/debian bullseye main contrib non-free
deb-src https://deb.debian.org/debian bullseye main contrib non-free

# Stable updates
deb https://deb.debian.org/debian bullseye-updates main contrib non-free
deb-src https://deb.debian.org/debian bullseye-updates main contrib non-free

# Stable backports
deb https://deb.debian.org/debian bullseye-backports main contrib non-free
deb-src https://deb.debian.org/debian bullseye-backports main contrib non-free
This file lists all sources of packages associated with the Bullseye version of Debian (the current Stable suite as of this writing). In the example above, we opted to name “bullseye” explicitly instead of using the corresponding “stable“ aliases (stable, stable-updates, stable-backports) because we don't want to have the underlying distribution changed outside of our control when the next stable release comes out.
Most packages will come from the “base repository”, which contains all packages but is seldom updated (about once every 2 months for a “point release”). The other repositories are partial (they do not contain all packages) and can host updates (packages with newer version) that APT might install. The following sections will explain the purpose and the rules governing each of those repositories.
Zauważ, że jeżeli pożądana wersja pakietu jest dostępna w kilku repozytoriach, to zostanie użyte pierwsze z nich występujące w pliku sources.list. Z tego powodu nieoficjalne źródła zazwyczaj są dodawane na końcu pliku.
Tak na marginesie, większość wiadomości z tej sekcji na temat wydania Stabilnego równie dobrze stosuje się do Oldstable, ponieważ to tylko starsza wersja Stabilnego, która jest utrzymywana równolegle.

6.1.2.1. Aktualizacje bezpieczeństwa

Debian takes security seriously. Known software vulnerabilities in Debian are tracked in the Security Bug Tracker and usually get fixed in a reasonable timeframe. The security updates are not hosted on the usual network of Debian mirrors but on security.debian.org, a small set of machines maintained by the Debian System Administrators. This archive contains security updates prepared by the Debian Security Team and/or by package maintainers for the Stable and Oldstable distribution.
The server can also host security updates for Testing but this doesn't happen very often since those updates tend to reach that suite via the regular flow of updates coming from Unstable.
For serious issues, the security team issues a Debian Security Advisory (DSA) and announces it together with the security update on the mailing list (archive).

6.1.2.2. Stabilne aktualizacje

Stabilne aktualizacje nie są wrażliwe ze względów bezpieczeństwa, ale uważane za wystarczająco ważne, aby udostępnić je użytkownikom przez kolejnym stabilnym wydaniem kropkowym.
This repository will typically contain fixes for critical and serious bugs which could not be fixed before release or which have been introduced by subsequent updates. Depending on the urgency, it can also contain updates for packages that have to evolve over time, like spamassassin's spam detection rules, clamav's virus database, the daylight-saving time rules of all timezones (tzdata), the ESR version of Firefox (firefox-esr) or cryptographic keyrings like debian-archive-keyring.
In practice, this repository is a subset of the proposed-updates repository, carefully selected by the Stable Release Managers. All updates are announced on the mailing list (archive) and will be included in the next Stable point release anyway.

6.1.2.3. Proponowane Aktualizacje

Po opublikowaniu, Stabilna dystrybucja jest aktualizowana tylko raz na 2 miesiące. Repozytorium proposed-updates jest miejscem, gdzie są przygotowywane spodziewane aktualizacje (pod nadzorem Stable Release Managers).
Aktualizacje bezpieczeństwa i stabilne opisane w poprzedniej sekcji są zawsze zawarte w tym repozytorium, ale jest też więcej, ponieważ zarządcy pakietów maja również okazję naprawienia ważnych błędów, które nie wymagają natychmiastowego wydania.
Anyone can use this repository to test those updates before their official publication. The extract below uses the bullseye-proposed-updates alias which is both more explicit and more consistent since buster-proposed-updates also exists (for the Oldstable updates):
deb https://deb.debian.org/debian bullseye-proposed-updates main contrib non-free

6.1.2.4. Stabilne Wsteczne Łatki

Repozytorium stable-backports hostuje "wsteczne łatki pakietów". Termin ten odnosi się do pakietu nowego oprogramowania, które zostało przekompilowane dla starszej dystrybucji, ogólnie dla Stabilnej.
When the distribution becomes a little dated, numerous software projects have released new versions that are not integrated into the current Stable suite, which is only modified to address the most critical problems, such as security issues. Since the Testing and Unstable suites can be more risky, package maintainers sometimes voluntarily offer recompilations of recent software applications for Stable, which has the advantage to users and system administrators to limit potential instability to a small number of chosen packages. The page https://backports.debian.org provides more information.
Backports from stable-backports are only created from packages available in Testing. This ensures that all installed backports will be upgradable to the corresponding stable version once the next stable release of Debian is available.
Even though this repository provides newer versions of packages, APT will not install them unless you give explicit instructions to do so (or unless you have already done so with a former version of the given backport):
$ sudo apt-get install package/bullseye-backports
$ sudo apt-get install -t bullseye-backports package

6.1.3. Repozytoria dla użytkowników Testowej/Niestabilnej

Poniżej jest standardowy plik sources.list dla systemu działającego pod kontrolą Testowej lub Niestabilnej wersji Debiana:

Przykład 6.3. plik /etc/apt/sources.list dla użytkowników Testowego/Niestabilnego Debiana

# Unstable
deb https://deb.debian.org/debian unstable main contrib non-free
deb-src https://deb.debian.org/debian unstable main contrib non-free

# Testing
deb https://deb.debian.org/debian testing main contrib non-free
deb-src https://deb.debian.org/debian testing main contrib non-free

# Testing security updates
deb http://security.debian.org/ testing-security main contrib non-free
deb-src http://security.debian.org/ testing-security main contrib non-free

# Stable
deb https://deb.debian.org/debian stable main contrib non-free
deb-src https://deb.debian.org/debian stable main contrib non-free

# Stable security updates
deb http://security.debian.org/ stable-security main contrib non-free
deb-src http://security.debian.org/ stable-security main contrib non-free
With this sources.list file APT will install packages from the Unstable suite. If that is not desired, use the APT::Default-Release setting (see Sekcja 6.2.3, „Uaktualnienie systemu”) to instruct APT to pick packages from another suite (most likely Testing in this case).
There are good reasons to include all those repositories, even though a single one should be enough. Testing users will appreciate the possibility to cherry-pick a fixed package from Unstable when the version in Testing is affected by an annoying bug. On the other hand, Unstable users bitten by unexpected regressions have the possibility to downgrade packages to their (supposedly working) Testing version.
The inclusion of Stable is more debatable but it often gives access to some packages, which have been removed from the development versions. It also ensures that you get the latest updates for packages, which have not been modified since the last stable release.

6.1.3.1. Repozytorium Eksperymentalnego

The archive of Experimental packages is present on all Debian mirrors, and contains packages which are not in the Unstable version yet because of their substandard quality — they are often software development versions or pre-versions (alpha, beta, release candidate…). A package can also be sent there after undergoing subsequent changes which can generate problems. The maintainer then tries to uncover them with help from advanced users who can handle important issues. After this first stage, the package is moved into Unstable, where it reaches a much larger audience and where it will be tested in much more detail.
Eksperymentalny jest używany głównie przez użytkowników, którym nie przeszkadza ciągłe psucie i naprawianie ich systemu. Taki podział pozwala w razie potrzeby na zaimportowanie pakietu, którego użytkownik chciałby wypróbować lub używać. Jest to również standardowe podejściem Debiana z nim związane, ponieważ dodanie go w pliku APTa sources.list nie powoduje systematycznego korzystania z jego pakietów. Linia, którą należy dodać to:
deb https://deb.debian.org/debian experimental main contrib non-free

6.1.4. Using Alternate Mirrors

The sources.list examples in this chapter refer to package repositories hosted on deb.debian.org. Those URLs will redirect you to servers which are close to you and which are managed by Content Delivery Networks (CDN) whose main role is to store multiple copies of the files across the world, and to deliver them as fast as possible to users. The CDN companies that Debian is working with are Debian partners who are offering their services freely to Debian. While none of those servers are under direct control of Debian, the fact that the whole archive is sealed by GPG signatures makes it a non-issue.
Picky users who are not satisfied with the performance of deb.debian.org can try to find a better mirror in the official mirror list:
But when you don't know which mirror is best for you, this list is of not much use. Fortunately for you, Debian maintains DNS entries of the form ftp.country-code.debian.org (e.g. ftp.us.debian.org for the USA, ftp.fr.debian.org for France, etc.) which are covering many countries and which are pointing to one (or more) of the best mirrors available within that country.
As an alternative to deb.debian.org, there used to be httpredir.debian.org. This service would identify a mirror close to you (among the list of official mirrors, using GeoIP mainly) and would redirect APT's requests to that mirror. This service has been deprecated due to reliability concerns and now httpredir.debian.org provides the same CDN-based service as deb.debian.org.

6.1.5. Non-Official Resources: mentors.debian.net

There are numerous non-official sources of Debian packages set up by advanced users who have recompiled some software — Ubuntu made this popular with their Personal Package Archive (PPA) service — by programmers who make their creation available to all, and even by Debian developers who offer pre-versions of their package online.
The mentors.debian.net site is interesting (although it only provides source packages), since it gathers packages created by candidates to the status of official Debian developer or by volunteers who wish to create Debian packages without going through that process of integration. These packages are made available without any guarantee regarding their quality; make sure that you check their origin and integrity and then test them before you consider using them in production.
Instalowanie pakietu oznacza przyznanie uprawnień root jego twórcy, ponieważ to on decyduje o zawartości skryptów inicjalizacyjnych, które są uruchamiane pod tą tożsamością. Oficjalne pakiety Debiana są tworzone przez wolontariuszy, z którymi współpracowano i zostali zweryfikowani oraz potrafią zabezpieczyć swój pakiet w taki sposób, aby było możliwe sprawdzenie jego pochodzenia i spójności.
In general, be wary of a package whose origin you don't know and which isn't hosted on one of the official Debian servers: evaluate the degree to which you can trust the creator, and check the integrity of the package.

6.1.6. Buforujący Pośrednik dla Pakietów Debiana

Kiedy cała sieć maszyn jest skonfigurowana, aby używać tego samego zdalnego serwera w celu pobierania tych samych zaktualizowanych pakiety, każdy administrator wie, że korzystnie byłoby mieć pośrednika działającego jako lokalna pamięć podręczna (spójrz na fiszkę SŁOWNIK Pamięć podręczna).
Można skonfigurować APT, żeby używał "standardowego" pośrednika (spójrz na fiszkę Sekcja 6.2.4, „Opcje konfiguracyjne” dotyczącą APTa i Sekcja 11.6, „HTTP/FTP Proxy” dotyczące pośrednika), ale ekosystem Debiana oferuje lepsze rozwiązania tego problemu. Przeznaczone do tego oprogramowanie, zaprezentowane w tej sekcji, jest lepsze od zwykłego pośrednika, ponieważ może używać specyficznej struktury repozytorium APTa (np.: wie, czy konkretne pliki są przestarzałe, czy nie i odpowiednio dopasowuje czas ich przetrzymywania).
apt-cacher i apt-cacher-ng działają jak zwykłe pośredniczące serwery buforowe. Plik sources.list nie jest zmieniany, ale APT jest skonfigurowany, aby używać ich jako pośredników dla wychodzących zapytań.
Z kolei approx działa jako serwer HTTP odzwierciedlając dowolną liczbę zdalnych repozytoriów pod jego adresami URL najwyższego poziomu. Mapowanie pomiędzy tymi katalogami najwyższego poziomu, a zdalnymi URLami repozytoriów jest przechowywane w pliku /etc/approx/approx.conf:
# <name>   <repository-base-url>
debian     https://deb.debian.org/debian
security   http://security.debian.org/debian-security
approx runs by default on port 9999 via a systemd socket and requires the users to adjust their sources.list file to point to the approx server:
# Sample sources.list pointing to a local approx server
deb http://localhost:9999/security bullseye-security main contrib non-free
deb http://localhost:9999/debian   bullseye main contrib non-free