A Short Introduction To Apt-Pinning - Page 2
3 Apt-Pinning
Now let's define that we prefer stable packages over testing packages and testing packages over unstable packages, and that packages from testing and unstable get installed only if there's no such package from stable:
vi /etc/apt/preferences
Package: * Pin: release a=stable Pin-Priority: 700 Package: * Pin: release a=testing Pin-Priority: 650 Package: * Pin: release a=unstable Pin-Priority: 600 |
In the Pin: release line you can use any of the attributes that you saw in the release line in the apt-cache policy output. For example, for Lenny that line was:
release v=5.0,o=Debian,a=stable,l=Debian,c=main
which means we could use Pin: release o=Debian, for example. But because testing and unstable also have o=Debian in the release line, we should use an attribute that distinguishes one release from the other - therefore I use a=stable|testing|unstable in /etc/apt/preferences.
If apt-cache policy showed something like this (this is from a server where I don't use testing and unstable, but a third-party repository) where the o= attribute differs...
server1:~# apt-cache policy
Package files:
100 /var/lib/dpkg/status
release a=now
500 http://volatile.debian.org lenny/volatile/main Packages
release o=volatile.debian.org,a=stable,l=debian-volatile,c=main
origin volatile.debian.org
650 http://download.openvz.org lenny/openvz Packages
release o=debian.systs.org lenny archive,a=stable,l=debian.systs.org lenny archive,c=openvz
origin download.openvz.org
700 http://security.debian.org lenny/updates/main Packages
release v=5.0,o=Debian,a=stable,l=Debian-Security,c=main
origin security.debian.org
700 http://ftp2.de.debian.org lenny/main Packages
release v=5.0,o=Debian,a=stable,l=Debian,c=main
origin ftp2.de.debian.org
Pinned packages:
server1:~#
... we could use
Package: *
Pin: release o=Debian
Pin-Priority: 700
Package: *
Pin: release o=debian.systs.org lenny archive
Pin-Priority: 650
in /etc/apt/preferences, for example.
Update the package database:
apt-get update
Let's check priorities again:
apt-cache policy
server1:~# apt-cache policy
Package files:
100 /var/lib/dpkg/status
release a=now
700 http://volatile.debian.org lenny/volatile/main Packages
release o=volatile.debian.org,a=stable,l=debian-volatile,c=main
origin volatile.debian.org
600 http://ftp2.de.debian.org sid/main Packages
release o=Debian,a=unstable,l=Debian,c=main
origin ftp2.de.debian.org
650 http://security.debian.org squeeze/updates/main Packages
release v=None,o=Debian,a=testing,l=Debian-Security,c=main
origin security.debian.org
650 http://ftp2.de.debian.org squeeze/main Packages
release o=Debian,a=testing,l=Debian,c=main
origin ftp2.de.debian.org
700 http://security.debian.org lenny/updates/main Packages
release v=5.0,o=Debian,a=stable,l=Debian-Security,c=main
origin security.debian.org
700 http://ftp2.de.debian.org lenny/main Packages
release v=5.0,o=Debian,a=stable,l=Debian,c=main
origin ftp2.de.debian.org
Pinned packages:
server1:~#
apt-cache policy phpmyadmin
server1:~# apt-cache policy phpmyadmin
phpmyadmin:
Installed: (none)
Candidate: 4:2.11.8.1-5
Version table:
4:3.1.3-1 0
600 http://ftp2.de.debian.org sid/main Packages
4:3.1.2-2 0
650 http://ftp2.de.debian.org squeeze/main Packages
4:2.11.8.1-5 0
700 http://ftp2.de.debian.org lenny/main Packages
server1:~#
As you see, now the phpmyadmin package from stable would get installed.
4 Holding A Package
Let's assume you've installed the phpmyadmin package from stable, and you want to tell apt to keep the current package under all circumstances. This is how you tell apt to never ever install another phpmyadmin package again:
vi /etc/apt/preferences
Package: phpmyadmin Pin: version 4:2.11.8.1* Pin-Priority: 1001 |
(This works with or without the stable, testing, and unstable stanzas from the previous chapter. So even if stable, testing, and unstable have the same priority, phpmyadmin is set to hold.)
As you see, I've added a stanza for the package phpmyadmin with the priority 1001. In the Pin: version line I use an asterisk (*). If you know the exact version of the package that you want to hold, you can of course specify it without an asterisk (Pin: version 4:2.11.8.1-5).
Run
apt-get update
again and check the policies:
apt-cache policy
server1:~# apt-cache policy
Package files:
100 /var/lib/dpkg/status
release a=now
700 http://volatile.debian.org lenny/volatile/main Packages
release o=volatile.debian.org,a=stable,l=debian-volatile,c=main
origin volatile.debian.org
600 http://ftp2.de.debian.org sid/main Packages
release o=Debian,a=unstable,l=Debian,c=main
origin ftp2.de.debian.org
650 http://security.debian.org squeeze/updates/main Packages
release v=None,o=Debian,a=testing,l=Debian-Security,c=main
origin security.debian.org
650 http://ftp2.de.debian.org squeeze/main Packages
release o=Debian,a=testing,l=Debian,c=main
origin ftp2.de.debian.org
700 http://security.debian.org lenny/updates/main Packages
release v=5.0,o=Debian,a=stable,l=Debian-Security,c=main
origin security.debian.org
700 http://ftp2.de.debian.org lenny/main Packages
release v=5.0,o=Debian,a=stable,l=Debian,c=main
origin ftp2.de.debian.org
Pinned packages:
phpmyadmin -> 4:2.11.8.1-5
server1:~#
apt-cache policy phpmyadmin
server1:~# apt-cache policy phpmyadmin
phpmyadmin:
Installed: 4:2.11.8.1-5
Candidate: 4:2.11.8.1-5
Package pin: 4:2.11.8.1-5
Version table:
4:3.1.3-1 1001
600 http://ftp2.de.debian.org sid/main Packages
4:3.1.2-2 1001
650 http://ftp2.de.debian.org squeeze/main Packages
*** 4:2.11.8.1-5 1001
700 http://ftp2.de.debian.org lenny/main Packages
100 /var/lib/dpkg/status
server1:~#
As you see, the Installed: and Candidate: lines both show the same version, so no other phpmyadmin package would get installed.
5 Installing Packages From A Specific Release/Overriding Priorities
(This chapter assumes you did not set phpmyadmin to hold, as was shown in chapter 4. If you did, this chapter will not work.)
Let's assume you prefer stable over testing and testing over unstable, but just not for the phpmyadmin package because the version from unstable has a feature that you absolutely need. So this is how you override your previously set up priorities and install phpmyadmin from unstable.
There are two ways of doing this, with a slight difference:
apt-get install phpmyadmin/unstable
This would install phpmyadmin from unstable, but apt would try to satisfy all phpmyadmin dependencies with packages from stable.
apt-get -t unstable install phpmyadmin
This would install phpmyadmin from unstable, and all phpmyadmin dependencies would also be installed from unstable.
