APT

apt command line utility

apt is a command line utility for package management.

In contrast to apt-get and apt-cache, apt is primarily intended for interactive use (as opposed to being used in scripts).

Repositories

TODO, see /etc/apt/sources.list, add-apt-repository

Packages

Upgrade a package

Probably with

$ sudo apt-get install --only-upgrade PACKAGE-NAME

Search for a package

apt-cache search   something
apt       search   something
apt-cache pkgnames something

apt-file search    regex

Find packages that contain a given file (here: /usr/bin/lspci). The following command uses the -x option to specify a regular expression (which explains why the searched file name is embedded in ^…$).

$ apt-file search -x '^/usr/bin/lspci$'
pciutils: /usr/bin/lspci

The command's output indicates that the package pciutils contains the file.

Show files of a package

Similarly, the files contained in a package can be shown with apt-file show:

$ apt-file show pciutils
pciutils: /usr/bin/lspci
pciutils: /usr/bin/setpci
pciutils: /usr/sbin/update-pciids
pciutils: /usr/share/doc/pciutils/README.gz
pciutils: /usr/share/doc/pciutils/changelog.Debian.gz
…

Get package records (Description, maintainer, homepage section etc.)

$ apt-cache show pciutils

Check if a package is installed

$ dpkg -s python3
$ dpkg-query -s

Dependencies

Forward dependencies (aka normal dependencies) denote the packages upon which a given package depends.

Reverse dependencies are the set of packages which depend on a given package.

Thus, when installing a package, its forward dependencies must be satisified.

Depdencies can be shown with

apt-cache showpkg
apt-cache depends
apt-cache rdepends

Binary vs source packages

There are two types of packages:

binary packages
source package

The content of a binary package is installed into a canonical location.

In contract, a source package is «installed» into an arbitrary directory.

Commands related to binary packages include

apt-src
apt build-dep
dpkg-source

Find out the URL of a package

$ sudo /usr/lib/apt-move/fetch -t apt-move
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
http://deb.debian.org/debian/pool/main/a/apt-move/apt-move_4.2.27-6_amd64.deb

If a package is not installed, the URL is also printed with the following command. Note: its --print-uris, not --print-urls!

$ apt-get install --print-uris  python3-asciitree

Package cache

The package cache is an database that stores information about all available packages.

The package cache can be queried with apt-cache.

Configuration

apt-config queries APT configuration directives from /etc/apt/apt.conf.

The content of the so-called configuration space can be shown with

apt-config dump

/etc/apt/apt-file.conf is used by apt-file (if the file is present).

Files and directories

		Configuration item
`/etc/apt`
`/etc/apt/sources.list`	Locations to fetch packages from.	`Dir::Etc::SourceList`
`/etc/apt/preferences.d/`
`/etc/apt/sources.list.d/`	File fragments for locations to fetch packages from.	`Dir::Etc::SourceParts`
`/var/lib/apt`
`/var/lib/dpkg/lock`	Compare with `/var/lib/dpkg/lock-frontend`
`/var/lib/apt/lists`	Storage area for state information for each package resource specified in `sources.list`	`Dir::State::Lists`
`/var/lib/apt/lists/partial/`	Storage area for state information in transit.	`Dir::State::Lists` (partial will be implicitly appended)
`/var/lib/apt/lists/lock`	Used to «lock» the `/var/lib/apt/lists` directory.
`/var/cache/apt/archives/`
`/var/cache/apt/partial/`

PPA: Personal Package Archives

A PPA is collection of packages that are hosted on Launchpad servers.

Find PPAs on launchpad with Personal Package Archives for Ubuntu

Preventing a package from getting upgrades

sudo apt-mark hold PKG

Misc

Interaction APT - dpkg

man 5 apt.conf has a section how APT calls dpkg which describes the configuration directives that control how APT invokes dpkg.

Launchpad

Launchpad offers as a service to host PPAs.

Source code

The source code for the APT tools is located at https://salsa.debian.org/apt-team/apt.

APT