Install afsctool with Homebrew, MacPorts, Nix

Project links

• Homepage
• Repository
• Upstream docs
• Package manager page

Commands and aliases

• afsctool
• zfsctool

Project history

The original afsctool was published by brkirch as a Mac OS X utility for HFS+ compression. The RJVB repository identifies itself as a modified version of brkirch's afsctool and documents changes around error reporting, large-file memory pressure, multiple file arguments, backups, read-only files, and parallel compression.

The RJVB fork became the source used by modern package managers. Its README records versioned feature work in the 1.6 and 1.7 series, including parallel compression options, additional compression types introduced by Apple in OS X 10.9 and later, LZVN support, and later LZFSE support.

Adoption history

afsctool is narrow but useful enough to appear in macOS-oriented package sets: the supplied facts list Homebrew, MacPorts, and Nix. That adoption tracks its niche: users who need to inspect or recompress files with Apple filesystem compression from scripts rather than through Finder or filesystem internals.

The RJVB fork also documents package-manager build dependencies and gives Homebrew and MacPorts examples, which helps explain why downstream formulae can build it despite the tool's macOS-specific subject matter.

How it is used

Typical usage is post-hoc compression or inspection of files and folders already on a supported filesystem. The RJVB fork adds options for parallel compression, sorting work items by size, and changing compression types when the operating system and linked libraries support them.

zfsctool, built from the same repository, adapts the afsctool idea to ZFS recompression statistics and experiments. The README is explicit that zfsctool is still a work in progress, so package users should treat afsctool as the primary stable executable.

Why package nerds care

afsctool is a classic small system package: obscure until you need it, highly platform-specific, and tightly bound to filesystem behavior and Apple compression formats. It is interesting to package maintainers because its dependency story and feature set move with macOS filesystem APIs and compression libraries.

The Homebrew formula exposes the RJVB fork rather than only the older brkirch page, so curation needs both sources: the original homepage explains the tool's purpose, while the repository explains the maintained code users actually install.

Timeline

• 2012: brkirch afsctool page published for the original AFSC utility.
• 2015: RJVB afsctool GitHub repository created.
• 2018: RJVB 1.6.9 release commit added size sorting and reverse-worker options for parallel mode.
• 2024: RJVB repository still receiving updates according to GitHub metadata.

Related projects

• Apple HFS+ and APFS filesystem compression are the core operating-system features afsctool manipulates.
• RJVB's LZVN fork and the lzfse/lzfse reference implementation are mentioned by the README as compression-library dependencies in the 1.7 series.
• zfsctool is the same repository's experimental ZFS-oriented companion utility.

Sources

• https://api.github.com/repos/RJVB/afsctool
• https://brkirch.wordpress.com/afsctool/
• https://github.com/RJVB/afsctool#readme
• source_facts.package-manager