POSIXconforming

POSIXconforming refers to software or systems that adhere to the POSIX family of standards (IEEE Std 1003), as maintained by The Open Group. POSIX defines a portable interface for operating systems, including C library functions, process and signal semantics, threading, file I/O, and a set of shell and utility interfaces intended to promote portability of software across different UNIX-like environments and other platforms.

Conformance is typically claimed for a particular edition or profile of POSIX, such as POSIX.1 for core APIs and POSIX.1c for threads, among others. A POSIXconforming implementation is expected to implement the specified interfaces and their documented behavior, including error reporting, behavior at program boundaries, and portability guarantees. Complete conformance is validated by running standardized conformance test suites aligned with the relevant POSIX edition; some suites are administered as part of a formal conformance program offered by The Open Group or other bodies.

In practice, many operating systems market themselves as POSIX-conforming or POSIX-compatible. However, conformance can vary by feature set and version; some optional extensions, non-POSIX interfaces, or platform-specific behavior may exist. Additionally, newer POSIX editions may update or augment requirements, so continued conformance may depend on system updates.

See also: POSIX, POSIX.1, POSIX.2, The Open Group, IEEE 1003, POSIX Certification, POSIX Test Suite.