CSA Standards

Information technology — Portable Operating System Interface (POSIX®) Base Specifications, Issue 7
 N CAN/CSA-ISO/IEC-9945-10

Annotation

Purpose

Several principles guided the development of POSIX.1-2008:

• Application-Oriented – The basic goal was to promote portability of application programs across UNIX system environments by developing a clear, consistent, and unambiguous standard for the interface • specification of a portable operating system based on the UNIX system documentation. POSIX.1-2008 codifies the common, existing definition of the UNIX system.

• Interface, Not Implementation – POSIX.1-2008 defines an interface, not an implementation. No distinction is made between library functions and system calls; both are referred to as functions. No details of the implementation of any function are given (although historical practice is sometimes indicated in the RATIONALE section). Symbolic names are given for constants (such as signals and error numbers) rather than numbers.

• Source, Not Object, Portability – POSIX.1-2008 has been written so that a program written and translated for execution on one conforming implementation may also be translated for execution on another conforming implementation. POSIX.1-2008 does not guarantee that executable (object or binary) code will execute under a different conforming implementation than that for which it was translated, even if the underlying hardware is identical.

• The C Language – The system interfaces and header definitions are written in terms of the standard C language as specified in the ISO C standard.

• No Superuser, No System Administration – There was no intention to specify all aspects of an operating system. System administration facilities and functions are excluded from this standard, and functions usable only by the superuser have not been included. Still, an implementation of the standard interface may also implement features not in POSIX.1-2008. POSIX.1-2008 is also not concerned with hardware constraints or system maintenance.