POSIXusing

POSIXusing is a software development approach that centers on building applications using the Portable Operating System Interface (POSIX) standards as the primary contract between software and the operating system. The term describes efforts to maximize portability across POSIX-compliant platforms, including Linux, macOS, FreeBSD, OpenBSD, NetBSD, Solaris, and IBM AIX.

POSIX provides a set of APIs for core operating system services, including file I/O, process control, signals, threading (POSIX threads), synchronization, timers, and standard C library facilities. POSIXusing advocates coding against these stable, documented interfaces rather than relying on vendor- or OS-specific extensions. Practitioners emphasize feature-testing, clear error handling, and consistent resource management to ensure portable behavior.

Adopting POSIXusing involves practical guidelines: prefer open, documented APIs; use feature test macros (such as _POSIX_C_SOURCE) to enable portable behavior; structure builds with tools like Autotools or CMake to detect available features; isolate non-POSIX code behind portable abstractions; and maintain separate code paths for non-POSIX targets when necessary. It also benefits from automated conformance tests and regular portability audits.

Limitations include uneven feature support across implementations, divergent behavior of some POSIX interfaces, and the challenge of targeting Windows without POSIX compatibility layers. While POSIXusing can greatly improve portability, it does not guarantee identical behavior across all environments, and pragmatic deviations are sometimes required.