Apple markets macOS as a UNIX® certified operating system, suggesting that the version running on Macs complies with the current UNIX standard. However, an examination of Apple’s own conformance statements submitted to The Open Group reveals that the certification does not reflect the standard macOS experience.
The UNIX trademark is tied to specific versions of the Single UNIX Specification (SUS). The latest SUS version 4 (2008, updated through 2018) corresponds to the UNIX® V7 trademark, but Apple’s macOS 15.0 only conforms to SUS version 3 from 2004, which earns the older UNIX® 03 trademark.
To pass the certification tests, Apple must alter the system in ways documented in the conformance statements: disabling System Integrity Protection (SIP), turning off timer coalescing, enabling the root user account, and mounting file systems with the strictatime option to obtain standard atime behavior.
The modified system used for testing is not the same as the macOS shipped to users, so the UNIX® label does not guarantee that a typical Mac meets the UNIX standard. While OSnews draws these conclusions from Apple’s supplied documents, it does not independently verify whether the practices violate The Open Group’s rules or assess the practical impact on developers and users.