How to use the command 'apt-cache' (with examples)

The ‘apt-cache’ command is a Debian and Ubuntu package query tool. It provides various commands to search and retrieve information about packages in the current sources. This article will illustrate each of the following use cases of the ‘apt-cache’ command.

Use case 1: Search for a package in your current sources

Code:

apt-cache search [query]

Motivation:

Searching for packages is useful when you want to install new software or find specific packages related to a particular keyword.

Explanation:

• ‘search’: This command is used to search for packages in the current sources based on a provided query.

Arguments:

• ‘[query]’: This argument represents the keyword or phrase you want to search for in package names and descriptions.

Example output:

libreoffice - Office productivity suite (metapackage)
libreoffice-l10n-za - LibreOffice language package for Zulu
libreoffice-l10n-zh-cn - LibreOffice language package for Chinese (Simplified)
...

Use case 2: Show information about a package

Code:

apt-cache show [package]

Motivation:

Viewing detailed information about a specific package is useful to understand its description, version, dependencies, and other relevant details.

Explanation:

• ‘show’: This command displays detailed information about a package.

Arguments:

• ‘[package]’: This argument represents the name of the package you want to view information about.

Example output:

Package: libreoffice
Version: 1:7.0.4-3
Installed-Size: 77.9 kB
Maintainer: Debian LibreOffice Maintainers <debian-openoffice@lists.debian.org>
Architecture: all
Depends: libreoffice-core (= 1:7.0.4-3), ...
...

Use case 3: Show whether a package is installed and up to date

Code:

apt-cache policy [package]

Motivation:

You might want to check if a package is installed or find its installed version and the available versions. This is helpful to ensure that your system is up to date and to verify the state of a particular package.

Explanation:

• ‘policy’: This command shows the installed and available versions of a package.

Arguments:

• ‘[package]’: This argument represents the name of the package you want to inspect.

Example output:

libreoffice:
  Installed: 1:7.0.4-3
  Candidate: 1:7.0.4-3
  Version table:
     1:7.0.4-3 500
        500 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages
        ...

Use case 4: Show dependencies for a package

Code:

apt-cache depends [package]

Motivation:

Understanding the dependencies of a package is important when you want to install or remove packages. It helps you identify other packages that may be installed or removed along with the target package.

Explanation:

• ‘depends’: This command displays the dependencies of a package.

Arguments:

• ‘[package]’: This argument represents the name of the package you want to view the dependencies for.

Example output:

libreoffice:
  Depends: libabsinthe-java
  Depends: libaccess-java
  Depends: libaccess-bridge-java
  ...

Use case 5: Show packages that depend on a particular package

Code:

apt-cache rdepends [package]

Motivation:

Finding packages that depend on a particular package is helpful when you want to identify packages that rely on a specific package. This information can be useful when you plan to modify or remove the target package.

Explanation:

• ‘rdepends’: This command displays the reverse dependencies of a package.

Arguments:

• ‘[package]’: This argument represents the name of the package you want to find reverse dependencies for.

Example output:

Reverse Depends:
  Replaces: cups-filters (<< 1.0.15-13)
  Recommends: libreoffice-avmedia-backend-gstreamer
libmythes7
  Depends: libreoffice-core

Conclusion:

The ‘apt-cache’ command is a versatile tool for package management in Debian and Ubuntu systems. By utilizing its various commands, you can search for packages, view information, check installation status, inspect dependencies, and find reverse dependencies. This knowledge enables you to manage packages effectively and ensure the stability and security of your system.