# Install udunits with Homebrew, apk, apt, MacPorts, Nix, zypper, dnf Unidata unit conversion library. Version 2.2.28 via Homebrew; verified from local package data. ## Install ```sh sudo av install brew:udunits ``` Additional install commands: ### macOS - Homebrew (100%): ```sh brew install udunits ``` Evidence: local Homebrew formula metadata - MacPorts (94%): ```sh sudo port install udunits ``` Evidence: MacPorts ports tree: science/udunits/Portfile from https://api.github.com/repos/macports/macports-ports/git/trees/master?recursive=1 ### Linux - apk (92%): ```sh sudo apk add udunits ``` Evidence: Alpine Linux edge package indexes: udunits from https://dl-cdn.alpinelinux.org/alpine/edge/community/x86_64/APKINDEX.tar.gz - Debian apt (92%): ```sh sudo apt install libudunits2-0 ``` Evidence: Debian stable package indexes: libudunits2-0 from https://deb.debian.org/debian/dists/stable/main/binary-amd64/Packages.xz - Nix (92%): ```sh nix profile install nixpkgs#udunits ``` Evidence: nixpkgs package indexes: pkgs/by-name/ud/udunits/package.nix from https://api.github.com/repos/NixOS/nixpkgs/git/trees/master?recursive=1 - zypper (92%): ```sh sudo zypper install udunits-compat ``` Evidence: openSUSE Tumbleweed package metadata: udunits-compat from https://download.opensuse.org/tumbleweed/repo/oss/repodata/be8d3611d25469107f32075a1697e69ec57a2b850b42348a658cc671ad5ec2b50760d02c3e59524d50da9a11d5be799bdaffba2e166e8ca8858512e3c0bd665d-primary.xml.zst - dnf (92%): ```sh sudo dnf install udunits2 ``` Evidence: Fedora Rawhide package metadata: udunits2 from https://dl.fedoraproject.org/pub/fedora/linux/development/rawhide/Everything/x86_64/os/repodata/e5ca8ce900cd68f5419e1c39ae517343100b306336cbaeb70a3c153121d95094-primary.xml.zst ## Package facts - **Package key:** brew:udunits - **Package manager:** Homebrew - **Package manager page:** - **Version:** 2.2.28 - **Source summary:** Unidata unit conversion library - **Homepage:** - **Repository:** - **Upstream docs:** - **License:** UCAR - **Source archive:** - **Generated:** 2026-07-08T07:18:31+00:00 ## Executables - udunits2 (cli) - udunits2 (alias) ## Build dependencies - texinfo ## Uses from macOS - expat ## Install behavior - Post-install hook: not defined - Bottle: available on arm64_big_sur, arm64_linux, arm64_monterey, arm64_sequoia, arm64_sonoma, arm64_tahoe, arm64_ventura, big_sur, catalina, monterey, sonoma, ventura ## Freshness - Page generated: 2026-07-08 - Package-manager version: 2.2.28 - Local data: ok - Upstream repository: https://docs.unidata.ucar.edu/udunits/current/ - info: No package-manager update timestamp was available. - info: Release/tag comparison is only available for GitHub repositories. ## Project history and usage UDUNITS is NSF Unidata's package for representing, manipulating, and converting units of physical quantities. It matters in package-manager culture because it is both a C library and a small command-line utility, so higher-level scientific packages can depend on it without each carrying its own unit database. ### Project history The current UDUNITS-2 line replaced the original UDUNITS-1 implementation while preserving broad compatibility. The official manual describes UDUNITS-2 as a C library, the `udunits2` unit-definition and conversion utility, and an extensive XML database of units. UDUNITS-2 changed the older package in several concrete ways: non-ASCII unit strings, logarithmic units, persistent value converters, a revised API, and an XML unit database with import support. The manual also notes that a version 1 C API is included for backward compatibility, making it a transition package as well as a new implementation. The changelog shows the project continuing through many 2.1 and 2.2 releases, with work on the command-line utility, Windows and CMake builds, unit database corrections, timestamp parsing, and portability fixes. Version 2.2.28 was published in December 2020 with documentation and release-engineering changes. ### Adoption history UDUNITS is part of the broader Unidata scientific software ecosystem, alongside tools such as netCDF. Its adoption pattern is typical of scientific infrastructure packages: it is rarely the end-user application, but it becomes a dependency below weather, climate, geoscience, and data-processing software that need consistent physical-unit parsing and conversion. The package-manager metadata in this batch shows the same infrastructure role across Unix-like ecosystems: Homebrew ships `udunits`, Debian and Ubuntu expose `libudunits2-0`, Fedora uses `udunits2`, and MacPorts and Nix also package it. That spread reflects a library that downstream scientific stacks expect to find from the system package manager. ### How it is used Library users call UDUNITS to parse unit strings, obtain binary unit representations, manipulate units arithmetically, and build converters between compatible units. Command-line users use `udunits2` to inspect unit definitions and convert numeric values. The XML unit database is a central usage point. The official documentation lists separate XML files for SI prefixes, SI base and derived units, SI-accepted units, and common non-SI units, and explains that the database is user-extensible. ### Why package nerds care UDUNITS is a classic scientific packaging dependency: small on the command line, important in ABI/API terms, and easy to overlook until a build of a larger scientific tool fails because unit parsing is missing. Its value to package nerds is that it externalizes a shared, curated unit database and conversion library instead of duplicating unit logic in every project. The package is also interesting because it straddles eras. It keeps compatibility with older UDUNITS-1 users while presenting a UDUNITS-2 API and XML database, so distribution maintainers care about headers, shared-library paths, data-file locations, and versioned downstream expectations. ### Timeline - 2009: UDUNITS-2 2.1.0 added a UDUNITS-1 compatibility API inside the new library. - 2011: The official GitHub repository was created. - 2014: UDUNITS-2 2.2.x development focused on documentation, CMake, Windows support, and unit database fixes. - 2020-12-28: UDUNITS 2.2.28 was published. ### Related projects - UDUNITS is published by NSF Unidata/UCAR and sits near other Unidata tools such as netCDF in scientific data workflows. - The original UDUNITS-1 package is directly related: UDUNITS-2 documents both differences from UDUNITS-1 and a compatibility C API. ### Sources - The official CHANGE_LOG in the repository records 2.1.x, 2.2.x, and 2.2.28 release details. - - - - source_facts.package-manager lists package names across Homebrew, Debian, Fedora, MacPorts, Nix, Ubuntu, and openSUSE. ## Security Notes library-like package without higher-risk signals. - **Geiger risk:** green / low - library-like package without higher-risk signals ## Source Database Details - **Source Database:** Homebrew formula API - **Tap:** homebrew/core - **Full Name:** udunits - **Version Scheme:** 0 - **Revision:** 0 - **Head Version:** HEAD - **Bottle Stable Root URL:** - **Deprecated:** no - **Disabled:** no - **Keg Only:** no - **URL Keys:** head, stable ## Other Package-Manager Records - Debian apt - libudunits2-0 - 2.2.28-7: normalized package name match | Debian stable package indexes: libudunits2-0 from https://deb.debian.org/debian/dists/stable/main/binary-amd64/Packages.xz | Library for handling of units of physical quantities | https://www.unidata.ucar.edu/software/udunits/ - Debian apt - libudunits2-data - 2.2.28-7: normalized package name match | Debian stable package indexes: libudunits2-data from https://deb.debian.org/debian/dists/stable/main/binary-amd64/Packages.xz | Data for handling of units of physical quantities | https://www.unidata.ucar.edu/software/udunits/ - Debian apt - libudunits2-dev - 2.2.28-7: normalized package name match | Debian stable package indexes: libudunits2-dev from https://deb.debian.org/debian/dists/stable/main/binary-amd64/Packages.xz | Development files for the libunits physical units package | https://www.unidata.ucar.edu/software/udunits/ - Debian apt - udunits-bin - 2.2.28-7: normalized package name match | Debian stable package indexes: udunits-bin from https://deb.debian.org/debian/dists/stable/main/binary-amd64/Packages.xz | Utility for handling units of physical quantities | https://www.unidata.ucar.edu/software/udunits/ - Nix - udunits: normalized package name match | nixpkgs package indexes: pkgs/by-name/ud/udunits/package.nix from https://api.github.com/repos/NixOS/nixpkgs/git/trees/master?recursive=1 - Ubuntu apt - libudunits2-0 - 2.2.28-7build1: normalized package name match | Ubuntu 24.04 LTS package indexes: libudunits2-0 from https://archive.ubuntu.com/ubuntu/dists/noble/universe/binary-amd64/Packages.gz | Library for handling of units of physical quantities | https://www.unidata.ucar.edu/software/udunits/ - Ubuntu apt - libudunits2-data - 2.2.28-7build1: normalized package name match | Ubuntu 24.04 LTS package indexes: libudunits2-data from https://archive.ubuntu.com/ubuntu/dists/noble/universe/binary-amd64/Packages.gz | Data for handling of units of physical quantities | https://www.unidata.ucar.edu/software/udunits/ - Ubuntu apt - libudunits2-dev - 2.2.28-7build1: normalized package name match | Ubuntu 24.04 LTS package indexes: libudunits2-dev from https://archive.ubuntu.com/ubuntu/dists/noble/universe/binary-amd64/Packages.gz | Development files for the libunits physical units package | https://www.unidata.ucar.edu/software/udunits/ - Ubuntu apt - udunits-bin - 2.2.28-7build1: normalized package name match | Ubuntu 24.04 LTS package indexes: udunits-bin from https://archive.ubuntu.com/ubuntu/dists/noble/universe/binary-amd64/Packages.gz | Utility for handling units of physical quantities | https://www.unidata.ucar.edu/software/udunits/ - apk - udunits - 2.2.28-r0: normalized package name match | Alpine Linux edge package indexes: udunits from https://dl-cdn.alpinelinux.org/alpine/edge/community/x86_64/APKINDEX.tar.gz | Library for handling of units of physical quantities | https://www.unidata.ucar.edu/software/udunits/ - apk - udunits-dev - 2.2.28-r0: normalized package name match | Alpine Linux edge package indexes: udunits-dev from https://dl-cdn.alpinelinux.org/alpine/edge/community/x86_64/APKINDEX.tar.gz | Library for handling of units of physical quantities (development files) | https://www.unidata.ucar.edu/software/udunits/ - apk - udunits-doc - 2.2.28-r0: normalized package name match | Alpine Linux edge package indexes: udunits-doc from https://dl-cdn.alpinelinux.org/alpine/edge/community/x86_64/APKINDEX.tar.gz | Library for handling of units of physical quantities (documentation) | https://www.unidata.ucar.edu/software/udunits/ - zypper - udunits-compat - 2.2.28-2.5: normalized package name match | openSUSE Tumbleweed package metadata: udunits-compat from https://download.opensuse.org/tumbleweed/repo/oss/repodata/be8d3611d25469107f32075a1697e69ec57a2b850b42348a658cc671ad5ec2b50760d02c3e59524d50da9a11d5be799bdaffba2e166e8ca8858512e3c0bd665d-primary.xml.zst | Udunits2 compatibility layer for udunits v1 API | https://www.unidata.ucar.edu/software/udunits/ - MacPorts - udunits: normalized package name match | MacPorts ports tree: science/udunits/Portfile from https://api.github.com/repos/macports/macports-ports/git/trees/master?recursive=1 - MacPorts - udunits2: installed executable or alias match | MacPorts ports tree: science/udunits2/Portfile from https://api.github.com/repos/macports/macports-ports/git/trees/master?recursive=1 - dnf - udunits2 - 2.2.28-13.fc44: installed executable or alias match | Fedora Rawhide package metadata: udunits2 from https://dl.fedoraproject.org/pub/fedora/linux/development/rawhide/Everything/x86_64/os/repodata/e5ca8ce900cd68f5419e1c39ae517343100b306336cbaeb70a3c153121d95094-primary.xml.zst | A library for manipulating units of physical quantities | http://www.unidata.ucar.edu/software/udunits/ ## Related links - [Terminal utility packages](https://www.automicvault.com/pkg/terminal-utilities/) - Matched terminal and command-line workflow metadata. - [Networking and protocol packages](https://www.automicvault.com/pkg/networking-protocol-tools/) - Matched network, protocol, or remote-service metadata. - [Scientific computing packages](https://www.automicvault.com/pkg/scientific-computing-tools/) - Matched scientific computing metadata. - [Documentation packages](https://www.automicvault.com/pkg/documentation-tools/) - Matched documentation, manual, or publishing metadata. - [texinfo](https://www.automicvault.com/pkg/brew/texinfo/) - Build dependency declared by Homebrew. - [nco](https://www.automicvault.com/pkg/brew/nco/) - Popular package that depends on this formula. - [ncview](https://www.automicvault.com/pkg/brew/ncview/) - Popular package that depends on this formula. - [gsl](https://www.automicvault.com/pkg/brew/gsl/) - Shares av.db curated category or tags: c, cli, science, scientific-computing. - [itk](https://www.automicvault.com/pkg/brew/itk/) - Shares av.db curated category or tags: cli, library, science, scientific-computing. - [libxc](https://www.automicvault.com/pkg/brew/libxc/) - Shares av.db curated category or tags: cli, library, science, scientific-computing. - 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Shared terms: cli, computing, science, scientific, scientific-computing. - [metis](https://www.automicvault.com/pkg/brew/metis/) - Local package facts share a topical domain. Shared terms: cli, computing, science, scientific, scientific-computing. ## Combined YAML source View the package source record on GitHub. [combined/udunits.yml](https://github.com/automic-vault/db/blob/main/combined/udunits.yml) ## Sources - Nucleus package database - Geiger risk classifier - package-page enrichment - curated package history - package version freshness - av.db category and tag curation - package relationship graph - external package-manager database matches - cross-ecosystem install command graph