Install b4 with Homebrew, apk, apt, dnf, Nix, pacman, zypper

Project links

• Homepage

Commands and aliases

• b4

Project history

b4 grew out of the Linux kernel community's long-running email patch workflow. Its documentation states that it was created to make it easier for developers and maintainers to use distributed workflows that rely on patches and distribution lists for contribution and review.

The project is hosted under kernel.org's utilities namespace and its docs are divided by role: maintainers who receive and apply series, reviewers who inspect patches, and contributors who prepare and send work. That structure mirrors the social workflow of kernel development more than a generic Git porcelain.

Adoption history

b4's adoption follows the public-inbox and lore.kernel.org era of kernel development: instead of scraping local mailboxes, it can operate against archived mailing-list threads by message id and then produce mbox, git-am, trailer, and review workflows.

The package metadata in this batch shows b4 available through Homebrew, Debian, Ubuntu, Fedora, Arch, Alpine, Nix, and openSUSE. That is a practical sign that the tool moved from kernel-maintainer specialty into the general Unix developer toolbox.

How it is used

Maintainers use b4 commands such as mbox, am, shazam, diff, pr, ty, review, and kr to fetch patch threads, apply series, compare revisions, process pull requests, send feedback, and work with contributor keys.

Contributors use b4 prep, send, and trailers to prepare patch series, send mail, and collect reviewed-by or acked-by trailers from mailing-list discussion. Configuration is intentionally Git-native, using system, user, repository, and optional .b4-config settings.

Why package nerds care

b4 is package-nerd gold because it packages a culture, not just a command. It encodes the Linux kernel's email-first review workflow into reproducible CLI steps that can be installed on macOS and Linux without joining the whole kernel.org infrastructure by hand.

It also marks the modern public-inbox turn in open-source packaging: source history, review, and artifact provenance are stitched together by message ids, Link trailers, and git metadata rather than by a web forge alone.

Timeline

• 2019: b4 documentation copyright begins, matching the period when kernel.org tooling around public-inbox workflows became formalized.
• 2022: b4 end-user docs cover maintainer and contributor workflows, including patch retrieval, application, diffing, pull requests, and automated feedback.
• 2026: b4 release notes document newer review and bug-tracking workflows, showing the tool expanding beyond patch retrieval into broader maintainer workflow support.

Related projects

• public-inbox and lore.kernel.org provide the archived mailing-list substrate b4 works against.
• git-am is the traditional Git patch-application workflow that b4 helps feed.
• git-config is the configuration mechanism used by b4.
• Patchwork and git-bug appear in b4's documented integrations and newer workflow areas.

Sources

• https://b4.docs.kernel.org/en/latest/
• https://b4.docs.kernel.org/en/latest/config.html
• https://b4.docs.kernel.org/en/latest/releases.html
• https://git.kernel.org/pub/scm/utils/b4/b4.git
• input.json source_facts.package-manager