How to use the command 'pacman --query' (with examples)

The command pacman --query is a versatile utility within the Arch Linux package management system, known as Pacman. It allows users to query the package database to obtain detailed information about installed packages on their system. Whether you want to check for installed software, determine package ownership of files, or manage package dependencies, pacman --query provides a set of tools for these tasks. Below are several examples of how you can leverage this command in different scenarios to streamline package management in Arch Linux.

Use case 1: List installed packages and versions

Code:

pacman --query

Motivation: When managing a system, knowing which packages are installed and their versions is crucial. This information helps in maintaining consistency across systems, debugging issues related to software versions, and planning upgrades or installations.

Explanation: The pacman --query command without any additional options simply retrieves and displays a list of all installed packages along with their versions. This base command is the beginning point for any query-related operation.

Example output:

acl 2.2.53-1
alsa-lib 1.2.3.2-1
bzip2 1.0.8-3
ca-certificates 20210119-1

Use case 2: List only packages and versions that were explicitly installed

Code:

pacman --query --explicit

Motivation: In a typical package management workflow on Arch Linux, packages can be installed explicitly by user request or as dependencies of other packages. Knowing which packages were explicitly installed helps in decluttering the system by allowing users to focus on the software they intentionally chose to install.

Explanation: The --explicit flag in conjunction with --query narrows down the list to only those packages that were manually installed by user choice, filtering out those that were pulled in as dependencies.

Example output:

firefox 82.0.3-1
vim 8.2.1989-1

Use case 3: Find which package owns a file

Code:

pacman --query --owns /usr/bin/vim

Motivation: Sometimes it’s necessary to determine which package installed a particular file on your system. This is particularly useful for troubleshooting, custom file management, or verifying the origin of a file to ensure system integrity.

Explanation: The --owns option allows users to input a file path to retrieve information about which package includes the specified file. This is a precise command ideal for tracking the source of files.

Example output:

vim-runtime 8.2.1989-1

Use case 4: Display information about an installed package

Code:

pacman --query --info vim

Motivation: Understanding the details of an installed package can be essential for verifying version numbers, installation status, source repositories, and dependencies. This information is vital for effective package management and planning updates or modifications.

Explanation: The --info flag with --query provides verbose package information, including version, build date, dependencies, and more—useful for users seeking a comprehensive view of a package’s properties.

Example output:

Name            : vim
Version         : 8.2.1989-1
Description     : Vi Improved, a highly configurable, improved version of the vi text editor
Architecture    : x86_64
URL             : https://www.vim.org

Use case 5: List files owned by a package

Code:

pacman --query --list vim

Motivation: At times, users may need to understand the scope of a package by knowing all the files that it has installed on the system. This is particularly helpful for inspecting installations, performing cleanups, or checking for configuration files.

Explanation: The --list option with --query generates a list of all files associated with a package. This allows users to fully understand what each package contributes to the file system.

Example output:

/usr/share/vim/vimfiles
/usr/share/vim/vim82

Use case 6: List orphan packages (installed as dependencies but not required by any package)

Code:

pacman --query --unrequired --deps --quiet

Motivation: Cleaning up unused dependencies is a routine maintenance task in system management to free up disk space and reduce clutter. Identifying orphan packages helps maintain a leaner system by uninstalling unnecessary packages.

Explanation: The --unrequired option identifies packages installed as dependencies that no longer have any packages depending on them. The --deps option ensures only dependencies are included, and --quiet suppresses additional output for a concise list.

Example output:

libfoo 1.0-1
libbar 2.0-1

Use case 7: List installed packages not found in the repositories

Code:

pacman --query --foreign

Motivation: From time to time, you may have packages installed from sources outside of official repositories—these are considered non-standard or foreign packages. Identifying these helps in ensuring they are kept up-to-date or are intentionally maintained separate from the main package flow.

Explanation: With the --foreign flag, pacman --query reveals packages that are not part of the official Arch Linux repositories, making it valuable for maintaining oversight on third-party software.

Example output:

google-chrome 86.0.4240.198-1
dropbox 106.4.368-1

Use case 8: List outdated packages

Code:

pacman --query --upgrades

Motivation: Keeping software up-to-date is critical for security and functionality. Outdated packages can introduce vulnerabilities and reduce performance. Identifying these packages ensures their proper updating, aligning system components with the latest features and fixes.

Explanation: By using the --upgrades option, pacman --query checks the system against the current repository data to flag any installed packages that are not up to the latest version available, prompting necessary updates.

Example output:

bash 5.0.18-2 -> 5.1.0-1
kernel 5.8.14-arch1-1 -> 5.9.0-arch1-1

Conclusion

The pacman --query command provides an array of functions indispensable for managing packages on an Arch Linux system. From listing installed packages to identifying orphans, outdated, and foreign software, these functionalities support system administrators and users in maintaining efficient, secure, and organized software environments. By leveraging these command options, users can ensure their systems are running optimally with the packages they need, and free from unnecessary or outdated software.