macOS Tahoe is certified Unix 03 [pdf]

Original Article ↗ Hacker News Discussion ↗

Status and Scope of Unix Certification

  • Thread notes that “UNIX V7” exists (2013) but is effectively only implemented by AIX today; Solaris used to qualify.
  • macOS is certified to an older Unix 03 profile; some wonder why there is no newer, more user-facing standard that mandates tools like curl, wget, git, jq, sqlite, gzip, etc.
  • C17 is now in the spec, but user-space tooling remains mostly out of scope; POSIX “Shell & Utilities” still doesn’t include curl/wget.

Why Apple Maintains Certification

  • Historical backstory: early Mac OS X marketing misused the UNIX trademark; certification was pursued to avoid legal trouble and as leverage internally.
  • Today, commenters speculate reasons: contractual checkboxes for governments/megacorps; cheap insurance against trademark risk; potential future marketing; extra regression test suite.
  • Others argue the benefit is marginal given that most customers only care that it’s “Unix-like,” not trademark UNIX.

Conformance Gaps and “Paper Unix” Critique

  • macOS’s poll(2) does not support devices, contradicting the Unix spec, yet certification is granted. People infer the Open Group is lenient.
  • OSNews piece and Open Group config docs show certification uses a non-default configuration: SIP disabled, APFS formatted case-sensitive, etc. The mass-market macOS image is therefore not literally the certified one.
  • Case-insensitive filesystems are allowed as an extension, but for “Unix-conformant behavior” Apple itself says to use case-sensitive APFS. Some commercial apps break on that.
  • Longstanding kernel/userland bugs (e.g., poll, fsync quirks) are said to linger for decades, contrasting with Linux/BSD.

Unix vs POSIX vs GNU/Linux Reality

  • Distinction stressed between POSIX and the Single UNIX Specification; POSIX is necessary but not sufficient for certification.
  • GNU tools intentionally diverge in small ways; POSIXLY_CORRECT and similar modes exist but aren’t default.
  • A few Linux distros were once Unix-certified, but maintaining that would make them subtly incompatible with “standard Linux” expectations, so vendors stopped.
  • Many argue the real de facto standard today is “Linux + GNU + common APIs,” not the trademark.

macOS as a Unix-like Developer Platform

  • Several commenters say they choose macOS specifically for a Unix-ish CLI plus polished hardware/desktop; certification per se doesn’t matter.
  • Others heavily replace the bundled BSD tools with Homebrew/MacPorts (GNU coreutils, grep, sed, etc.).
  • Some fear dropping certification might accelerate removal/neglect of Unix-like tooling; others think Apple understands developer needs regardless.
  • WSL on Windows is cited as a parallel: vendors can’t ignore Unix-style tooling without hurting developer adoption.

Standards and Future Directions

  • There’s nostalgia for the 80s–90s “open standards will define Unix” era; consensus is that open source and de facto practice ultimately won.
  • A “living” POSIX-like standard is proposed; responses argue that slower, conservative revisions (vs web-style rapid change) are healthier, with standards mostly ratifying what BSD/Linux already converge on.