apt-cache
command can display much of the information stored in APT's internal database. This information is a sort of cache since it is gathered from the different sources listed in the sources.list
file. This happens during the apt update
operation.
apt-cache
command can do keyword-based package searches with apt-cache search keyword
. It can also display the headers of the package's available versions with apt-cache show package
. This command provides the package's description, its dependencies, the name of its maintainer, etc. Note that apt search
, apt show
, aptitude search
, and aptitude show
work in the same way.
apt-cache dumpavail
displays the headers of all available versions of all packages. apt-cache pkgnames
displays the list of all the packages which appear at least once in the cache.
apt-cache policy
, described in the following section.
apt-cache policy
command displays the pinning priorities and distribution properties of each package source as explained in Section 6.2.5, “Managing Package Priorities”. It can also show the pinning priorities for all available versions and sources of a package. For the sources.list
example used in Example 6.2, “/etc/apt/sources.list
file for users of Debian Stable” and APT::Default-Release
set to "bullseye"
, the output will look like this:
$
apt-cache policy
Package files: 100 /var/lib/dpkg/status release a=now 100 https://deb.debian.org/debian bullseye-backports/main amd64 Packages release o=Debian Backports,a=bullseye-backports,n=bullseye-backports,l=Debian Backports,c=main,b=amd64 origin deb.debian.org 990 https://deb.debian.org/debian bullseye/non-free amd64 Packages release v=11.0,o=Debian,a=stable,n=bullseye,l=Debian,c=non-free,b=amd64 origin deb.debian.org 990 https://deb.debian.org/debian bullseye/contrib amd64 Packages release v=11.0,o=Debian,a=stable,n=bullseye,l=Debian,c=contrib,b=amd64 origin deb.debian.org 990 https://deb.debian.org/debian bullseye/main amd64 Packages release v=11.0,o=Debian,a=stable,n=bullseye,l=Debian,c=main,b=amd64 origin deb.debian.org 500 http://security.debian.org bullseye-security/main amd64 Packages release v=11,o=Debian,a=stable-security,n=bullseye-security,l=Debian-Security,c=main,b=amd64 origin security.debian.org Pinned packages:
apt-cache policy
can also show the pinning priorities for all available versions and sources of a given package.
$
apt-cache policy limnoria
limnoria: Installed: 2021.06.15-1 Candidate: 2021.06.15-1 Version table: 2021.07.21-1~bpo11+1 100 100 https://deb.debian.org/debian bullseye-backports/main amd64 Packages *** 2021.06.15-1 990 990 https://deb.debian.org/debian bullseye/main amd64 Packages 100 /var/lib/dpkg/status
bullseye-backports
repository, APT will not install it automatically based on the priority. One would have to use apt install limnoria/bullseye-backports
or add a higher pinning priority to /etc/apt/preferences.d/limnoria.pref
:
Package: limnoria Pin: release o=Debian Backports, a=bullseye-backports Pin-Priority: 1001
$
apt-cache policy limnoria
limnoria: Installed: 2021.06.15-1 Candidate: 2021.07.21-1~bpo11+1 Version table: 2021.07.21-1~bpo11+1 1001 100 https://deb.debian.org/debian bullseye-backports/main amd64 Packages *** 2021.06.15-1 990 990 https://deb.debian.org/debian bullseye/main amd64 Packages 100 /var/lib/dpkg/status