Datasheet

98
Part I ✦ The Fundamentals
Candidate: 1:1.3.4-1
Version Table:
1:1.3.4-1 0
500 http://http.us.debian.org sid/main Packages
500 http://http.us.debian.org etch/main Packages
*** 1:1.3.2-1.sarge.1 0
100 /var/lib/dpkg/status
1:1.3.2-1.sarge.1 0
500 http://http.us.debian.org sarge/main Packages
(The version numbers may be different by the time you read this, but the same
principles apply.) What the output is telling you is that I currently have version
1:1.3.2-1 of
kword installed. (/var/lib/dpkg/status, which is dpkg’s database, is
treated as the source of the package.)
apt has assigned this version a score of 100.
Sarge currently has the same version, which has a score of 500, as does 1:1.3.4-1
in etch/sid.
kword doesn’t exist in experimental. As both the versions in sarge and
etch/sid have the same score, the tie is broken by the higher version. The number
after the version is the priority of the package, which is set only if you pin by
version — see the “Installing (or keeping) a specific version” section) — so it is 0
here.
/etc/apt/preferences
Were I to do an upgrade of kword now, the version from testing/unstable would be
the candidate for installation. Because
kword 1:1.3.4-1 depends on other packages
from testing/unstable, installing it could inadvertently result in a large part of my
system being upgraded to unstable. So be very careful in using pinning with com-
mon library packages such as
libc6, which large numbers of packages depend on.
This can be prevented by creating a file called
/etc/apt/preferences with con-
tents like this:
Explanation: Sarge
Package: *
Pin: release a=stable
Pin-Priority: 999
Explanation: Etch
Package: *
Pin: release a=testing
Pin-Priority: 90
Explanation: Sid
Package: *
Pin: release a=unstable
Pin-Priority: 80
Package: *
Pin: release a=experimental
Pin-Priority: 10
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