consideremos que neste momento estamos a utilizar a versão estável do debian (buster) mas que pretendemos instalar um pacote específico (por ex: iputils-ping) da versão testing (bullseye) (este tipo de ação tem que ser sempre devidamente ponderado na medida em que determinados pacotes, pela quantidade de dependências que têm, poderão levar a uma situação de inconsistência do sistema).
começamos por adicionar o repositório da versão testing:
printf 'deb http://ftp.pt.debian.org/debian/ bullseye main contrib non-free' > /etc/apt/sources.list.d/bullseye.list
de seguida atualizamos a lista de pacotes disponíveis com:
apt update
através da utilização do comando seguinte conseguimos compreender a prioridade global de cada repositório definido no nosso sistema:
apt-cache policy
e o resultado:
Ficheiros de Pacotes :
100 /var/lib/dpkg/status
release a=now
500 https://download.virtualbox.org/virtualbox/debian buster/contrib amd64 Packages
release o=Oracle Corporation,n=buster,l=Oracle Corporation,c=contrib,b=amd64
origin download.virtualbox.org
500 http://linux.teamviewer.com/deb stable/main i386 Packages
release o=TeamViewer GmbH,a=stable,l=TeamViewer,c=main,b=i386
origin linux.teamviewer.com
500 http://linux.teamviewer.com/deb stable/main amd64 Packages
release o=TeamViewer GmbH,a=stable,l=TeamViewer,c=main,b=amd64
origin linux.teamviewer.com
500 https://mega.nz/linux/MEGAsync/Debian_10.0 ./ Packages
release o=obs://private/DEB/Debian_10,n=Debian_10,l=DEB,c=
origin mega.nz
500 http://dl.google.com/linux/earth/deb stable/main amd64 Packages
release v=1.0,o=Google LLC,a=stable,n=stable,l=Google,c=main,b=amd64
origin dl.google.com
100 http://deb.debian.org/debian buster-backports/contrib i386 Packages
release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=contrib,b=i386
origin deb.debian.org
100 http://deb.debian.org/debian buster-backports/contrib amd64 Packages
release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=contrib,b=amd64
origin deb.debian.org
100 http://deb.debian.org/debian buster-backports/main i386 Packages
release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=main,b=i386
origin deb.debian.org
100 http://deb.debian.org/debian buster-backports/main amd64 Packages
release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=main,b=amd64
origin deb.debian.org
500 http://ftp.pt.debian.org/debian bullseye/non-free i386 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=non-free,b=i386
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/non-free amd64 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=non-free,b=amd64
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/contrib i386 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=contrib,b=i386
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/contrib amd64 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=contrib,b=amd64
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/main i386 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=main,b=i386
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/main amd64 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=main,b=amd64
origin ftp.pt.debian.org
500 http://httpredir.debian.org/debian stretch/non-free i386 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=non-free,b=i386
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/non-free amd64 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=non-free,b=amd64
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/contrib i386 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=contrib,b=i386
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/contrib amd64 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=contrib,b=amd64
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/main i386 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=main,b=i386
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/main amd64 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=main,b=amd64
origin httpredir.debian.org
500 https://www.deb-multimedia.org buster/non-free i386 Packages
release v=10.1,o=Unofficial Multimedia Packages,a=stable,n=buster,l=Unofficial Multimedia Packages,c=non-free,b=i386
origin www.deb-multimedia.org
500 https://www.deb-multimedia.org buster/non-free amd64 Packages
release v=10.1,o=Unofficial Multimedia Packages,a=stable,n=buster,l=Unofficial Multimedia Packages,c=non-free,b=amd64
origin www.deb-multimedia.org
500 https://www.deb-multimedia.org buster/main i386 Packages
release v=10.1,o=Unofficial Multimedia Packages,a=stable,n=buster,l=Unofficial Multimedia Packages,c=main,b=i386
origin www.deb-multimedia.org
500 https://www.deb-multimedia.org buster/main amd64 Packages
release v=10.1,o=Unofficial Multimedia Packages,a=stable,n=buster,l=Unofficial Multimedia Packages,c=main,b=amd64
origin www.deb-multimedia.org
500 https://download.docker.com/linux/debian buster/stable amd64 Packages
release o=Docker,a=buster,l=Docker CE,c=stable,b=amd64
origin download.docker.com
500 http://liveusb.info/multisystem/depot all/main i386 Packages
release v=all,o=liveusb.info,a=all,n=all,l=Dêpot MultiSystem liveusb.info,c=main,b=i386
origin liveusb.info
500 http://liveusb.info/multisystem/depot all/main amd64 Packages
release v=all,o=liveusb.info,a=all,n=all,l=Dêpot MultiSystem liveusb.info,c=main,b=amd64
origin liveusb.info
500 http://security.debian.org/debian-security buster/updates/main i386 Packages
release v=10,o=Debian,a=stable,n=buster,l=Debian-Security,c=main,b=i386
origin security.debian.org
500 http://security.debian.org/debian-security buster/updates/main amd64 Packages
release v=10,o=Debian,a=stable,n=buster,l=Debian-Security,c=main,b=amd64
origin security.debian.org
500 http://ftp.pt.debian.org/debian buster/non-free i386 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=non-free,b=i386
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian buster/non-free amd64 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=non-free,b=amd64
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian buster/contrib i386 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=contrib,b=i386
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian buster/contrib amd64 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=contrib,b=amd64
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian buster/main i386 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=main,b=i386
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian buster/main amd64 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=main,b=amd64
origin ftp.pt.debian.org
Pacotes Marcados:
neste caso em específico, à excepção dos pacotes instalados localmente e do repositório buster-backports, a negrito no resultado anterior, todos os outros repositórios têm a mesma prioridade.
olhemos agora especificamente para o pacote iputils-ping:
apt-cache policy iputils-ping
e o resultado:
iputils-ping:
Instalado: 3:20180629-2
Candidato: 3:20190709-1
Tabela de Versão:
3:20190709-1 500
500 http://ftp.pt.debian.org/debian bullseye/main amd64 Packages
*** 3:20180629-2 500
500 http://ftp.pt.debian.org/debian buster/main amd64 Packages
100 /var/lib/dpkg/status
3:20161105-1 500
500 http://httpredir.debian.org/debian stretch/main amd64 Packages
conseguimos compreender que o pacote atualmente instalado é o da versão estável, buster, mas que se o reinstalarmos passaremos a ter no sistema o pacote da versão testing (tem a mesma prioridade - 500 - e é mais recente). senão vejamos:
apt reinstall iputils-ping
apt-cache policy iputils-ping
e o resultado do último comando:
iputils-ping:
Instalado: 3:20190709-1
Candidato: 3:20190709-1
Tabela de Versão:
*** 3:20190709-1 500
500 http://ftp.pt.debian.org/debian bullseye/main amd64 Packages
100 /var/lib/dpkg/status
3:20180629-2 500
500 http://ftp.pt.debian.org/debian buster/main amd64 Packages
3:20161105-1 500
500 http://httpredir.debian.org/debian stretch/main amd64 Packages
onde podemos ver que o pacote foi substituído.
esta situação poderá levar a uma inconsistẽncia do nosso sistema. para evitarmos que aconteça devemos, manualmente, alterar as prioridades dos repositórios de acordo com as nossas necessidades. isso consegue-se através da criação/edição de um ficheiro na pasta /etc/apt/preferences.d/ que pode ser, por exemplo, 99minhas_prioridades e de acordo com o conteúdo seguinte:
Package: *
Pin: release n=buster
Pin-Priority: 1000Package: iputils-ping
Pin: release n=bullseye
Pin-Priority: 1000
a nossa opção foi a de definir uma prioridade de 1000 para todos os pacotes do repositório buster e a mesma prioridade para o pacote iputils-ping do repositório bullseye. assim garantimos que à exceção do pacote iputils-ping, que será instalado do repositório bullseye, todos os outros serão instalados do repositório buster.
podemos ver isso se olharmos para o final do resultado do comando:
apt-cache policy
e o resultado:
Ficheiros de Pacotes :
100 /var/lib/dpkg/status
release a=now
1000 https://download.virtualbox.org/virtualbox/debian buster/contrib amd64 Packages
release o=Oracle Corporation,n=buster,l=Oracle Corporation,c=contrib,b=amd64
origin download.virtualbox.org
500 http://linux.teamviewer.com/deb stable/main i386 Packages
release o=TeamViewer GmbH,a=stable,l=TeamViewer,c=main,b=i386
origin linux.teamviewer.com
500 http://linux.teamviewer.com/deb stable/main amd64 Packages
release o=TeamViewer GmbH,a=stable,l=TeamViewer,c=main,b=amd64
origin linux.teamviewer.com
500 https://mega.nz/linux/MEGAsync/Debian_10.0 ./ Packages
release o=obs://private/DEB/Debian_10,n=Debian_10,l=DEB,c=
origin mega.nz
500 http://dl.google.com/linux/earth/deb stable/main amd64 Packages
release v=1.0,o=Google LLC,a=stable,n=stable,l=Google,c=main,b=amd64
origin dl.google.com
100 http://deb.debian.org/debian buster-backports/contrib i386 Packages
release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=contrib,b=i386
origin deb.debian.org
100 http://deb.debian.org/debian buster-backports/contrib amd64 Packages
release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=contrib,b=amd64
origin deb.debian.org
100 http://deb.debian.org/debian buster-backports/main i386 Packages
release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=main,b=i386
origin deb.debian.org
100 http://deb.debian.org/debian buster-backports/main amd64 Packages
release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=main,b=amd64
origin deb.debian.org
500 http://ftp.pt.debian.org/debian bullseye/non-free i386 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=non-free,b=i386
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/non-free amd64 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=non-free,b=amd64
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/contrib i386 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=contrib,b=i386
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/contrib amd64 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=contrib,b=amd64
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/main i386 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=main,b=i386
origin ftp.pt.debian.org
500 http://ftp.pt.debian.org/debian bullseye/main amd64 Packages
release o=Debian,a=testing,n=bullseye,l=Debian,c=main,b=amd64
origin ftp.pt.debian.org
500 http://httpredir.debian.org/debian stretch/non-free i386 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=non-free,b=i386
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/non-free amd64 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=non-free,b=amd64
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/contrib i386 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=contrib,b=i386
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/contrib amd64 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=contrib,b=amd64
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/main i386 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=main,b=i386
origin httpredir.debian.org
500 http://httpredir.debian.org/debian stretch/main amd64 Packages
release v=9.11,o=Debian,a=oldstable,n=stretch,l=Debian,c=main,b=amd64
origin httpredir.debian.org
1000 https://www.deb-multimedia.org buster/non-free i386 Packages
release v=10.1,o=Unofficial Multimedia Packages,a=stable,n=buster,l=Unofficial Multimedia Packages,c=non-free,b=i386
origin www.deb-multimedia.org
1000 https://www.deb-multimedia.org buster/non-free amd64 Packages
release v=10.1,o=Unofficial Multimedia Packages,a=stable,n=buster,l=Unofficial Multimedia Packages,c=non-free,b=amd64
origin www.deb-multimedia.org
1000 https://www.deb-multimedia.org buster/main i386 Packages
release v=10.1,o=Unofficial Multimedia Packages,a=stable,n=buster,l=Unofficial Multimedia Packages,c=main,b=i386
origin www.deb-multimedia.org
1000 https://www.deb-multimedia.org buster/main amd64 Packages
release v=10.1,o=Unofficial Multimedia Packages,a=stable,n=buster,l=Unofficial Multimedia Packages,c=main,b=amd64
origin www.deb-multimedia.org
500 https://download.docker.com/linux/debian buster/stable amd64 Packages
release o=Docker,a=buster,l=Docker CE,c=stable,b=amd64
origin download.docker.com
500 http://liveusb.info/multisystem/depot all/main i386 Packages
release v=all,o=liveusb.info,a=all,n=all,l=Dêpot MultiSystem liveusb.info,c=main,b=i386
origin liveusb.info
500 http://liveusb.info/multisystem/depot all/main amd64 Packages
release v=all,o=liveusb.info,a=all,n=all,l=Dêpot MultiSystem liveusb.info,c=main,b=amd64
origin liveusb.info
1000 http://security.debian.org/debian-security buster/updates/main i386 Packages
release v=10,o=Debian,a=stable,n=buster,l=Debian-Security,c=main,b=i386
origin security.debian.org
1000 http://security.debian.org/debian-security buster/updates/main amd64 Packages
release v=10,o=Debian,a=stable,n=buster,l=Debian-Security,c=main,b=amd64
origin security.debian.org
1000 http://ftp.pt.debian.org/debian buster/non-free i386 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=non-free,b=i386
origin ftp.pt.debian.org
1000 http://ftp.pt.debian.org/debian buster/non-free amd64 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=non-free,b=amd64
origin ftp.pt.debian.org
1000 http://ftp.pt.debian.org/debian buster/contrib i386 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=contrib,b=i386
origin ftp.pt.debian.org
1000 http://ftp.pt.debian.org/debian buster/contrib amd64 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=contrib,b=amd64
origin ftp.pt.debian.org
1000 http://ftp.pt.debian.org/debian buster/main i386 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=main,b=i386
origin ftp.pt.debian.org
1000 http://ftp.pt.debian.org/debian buster/main amd64 Packages
release v=10.1,o=Debian,a=stable,n=buster,l=Debian,c=main,b=amd64
origin ftp.pt.debian.org
Pacotes Marcados:
iputils-ping -> 3:20190709-1 with priority 1000
substituir o pacote iputils-ping da versão estável para a versão testing do debian num só comando:
printf 'deb http://ftp.pt.debian.org/debian/ bullseye main contrib non-free' > /etc/apt/sources.list.d/bullseye.list && printf '%s\n' 'Package: *' 'Pin: release n=bullseye' 'Pin-Priority: 100' '' 'Package: iputils-ping' 'Pin: release n=bullseye' 'Pin-Priority: 1000' > /etc/apt/preferences.d/99minhas-prioridades && apt update && apt reinstall iputils-ping -y
https://wiki.debian.org/AptConfiguration
https://manpages.debian.org/buster/apt/apt_preferences.5.pt.html