How To Query Package Information In Debian And Ubuntu

If you're a Linux user, especially on a Debian-based system like Ubuntu, you've probably heard of apt-get and apt. These are powerful tools for managing software packages. But did you know there's another command-line tool called apt-cache that can help you query package information quickly and efficiently? In this brief tutorial, we'll discuss what apt-cache is, how to use it to query package information in Debian, Ubuntu and its derivatives.

What is apt-cache?

apt-cache is a command-line utility that allows you to query the package information stored in your system's package cache. This tool is useful for searching for packages, displaying detailed information about them, and understanding their dependencies. Unlike apt-get, which is used for installing and removing packages, apt-cache focuses on providing information about available packages.

Common apt-cache Commands

Here are some of the most common apt-cache commands you'll use:

1. Search for Packages

To search for packages that match a specific keyword, use the following command:

apt-cache search keyword

Example:

apt-cache search image editor

This command searches for packages that match to the keywords "image" and "editor" and lists them along with a brief description.

Sample Output:

fontforge - font editor
fontforge-nox - font editor - non-X version
gimp - GNU Image Manipulation Program
libreoffice - office productivity suite (metapackage)
android-platform-tools-base - base tools for developing applications for the Android system
briquolo-data - data files for the fast paced 3d Breakout game Briquolo
charactermanaj - avatar editor application
chntpw - NT SAM password recovery utility
copyq - Advanced clipboard manager with editing and scripting features
copyq-plugins - Plugins for CopyQ
digikam - digital photo management application for KDE
showfoto - image viewer/editor for KDE
drawing - simple drawing application for the GNOME desktop
ephoto - Comprehensive Image Viewer Using EFL
fim - scriptable frame buffer, X.org and ascii art image viewer
[...]

2. Show Package Details

To display detailed information about a specific package, use the following command:

apt-cache show package_name

Example:

apt-cache show firefox-esr

This command shows detailed information about the Firefox browser, including its version, description, and more.

3. Show Package Dependencies

To see the dependencies of a specific package, use the following command:

apt-cache depends package_name

Example:

apt-cache depends linux-image-amd64

This command lists all the dependencies required by the linux-image-amd64 package.

Sample Output:

linux-image-amd64
  Depends: linux-image-6.1.0-25-amd64

4. Show Package Installation Policy

To display the installation policy for a specific package, use the following command:

apt-cache policy package_name

Example:

apt-cache policy python3

This command shows the installation policy for Python 3, including the available versions and their priorities.

Sample Output:

python3:
  Installed: 3.11.2-1+b1
  Candidate: 3.11.2-1+b1
  Version table:
 *** 3.11.2-1+b1 500
        500 http://deb.debian.org/debian bookworm/main amd64 Packages
        100 /var/lib/dpkg/status

5. List All Package Names

To list all the package names available in your cache, use the following command:

apt-cache pkgnames

This command is useful if you want to see a comprehensive list of all packages available for installation.

6. Display Cache Statistics

To display statistics about your package cache, use the following command:

apt-cache stats

This command provides information about the number of packages, their sizes, and more.

Sample Output:

Total package names: 122971 (3,443 k)
Total package structures: 109860 (4,834 k)
  Normal packages: 64508
  Pure virtual packages: 1088
  Single virtual packages: 34397
  Mixed virtual packages: 448
  Missing: 9419
Total distinct versions: 67184 (5,912 k)
Total distinct descriptions: 131717 (3,161 k)
Total dependencies: 412137/110983 (10.0 M)
Total ver/file relations: 5497 (132 k)
Total Desc/File relations: 645 (15.5 k)
Total Provides mappings: 39988 (960 k)
Total globbed strings: 221945 (5,173 k)
Total slack space: 104 k
Total space accounted for: 35.3 M
Total buckets in PkgHashTable: 196613
  Unused: 112576
  Used: 84037
  Utilization: 42.7423%
  Average entries: 1.30728
  Longest: 17
  Shortest: 1
Total buckets in GrpHashTable: 196613
  Unused: 105223
  Used: 91390
  Utilization: 46.4822%
  Average entries: 1.34556
  Longest: 7
  Shortest: 1

Benefits of Using apt-cache

• Quick Package Searches: apt-cache allows you to quickly search for packages by keyword, making it easy to find the software you need.
• Detailed Package Information: With apt-cache, you can access detailed information about any package, including its version, description, and more.
• Dependency Resolution: Understanding a package's dependencies is crucial for troubleshooting and ensuring smooth installation. apt-cache makes it easy to view these dependencies.

Conclusion

apt-cache is a useful tool for querying package information on Debian-based Linux systems. Whether you're searching for a specific package, looking for detailed information, or understanding dependencies, apt-cache makes it easy.

So next time you need to find out more about a package, remember to use apt-cache!