POSIX, which stands for Portable Operating System Interface for computing environments, began as an effort by the IEEE community to promote the portability of applications across UNIX environments by developing a clear, consistent, and unambiguous set of standards. POSIX is not limited to the UNIX environment, however. It can be implemented on non-UNIX operating systems, as was done with the IEEE Std. 1003.1-1990 (POSIX.1) implementation on the VMS, MPE, and CTOS operating systems. POSIX actually consists of a set of standards that range from POSIX.1 to POSIX.12.
As the following table shows, most of these standards are still in the proposed state. This section deals with the Windows NT implementation of a POSIX subsystem to support the international ISO/IEC IS 9945-1:1990 standard (also called POSIX.1). POSIX.1 defines a C-language source-code-level application programming interface (API) to an operating system environment.
Table 29.1 Family of POSIX Standards
Standard | ISO Standard | Description | |
POSIX.0 | No | A guide to POSIX Open Systems Environment. This is not a standard in the same sense as POSIX.1 or POSIX.2. It is more of an introduction and overview of the other standards. | |
POSIX.1 | Yes | Systems application programming interface (API) [C language]. | |
POSIX.2 | No | Shell and tools (IEEE approved standard). | |
POSIX.3 | No | Testing and verification. | |
POSIX.4 | No | Real-time and threads. | |
POSIX.5 | Yes | ADA language bindings to POSIX.1. | |
POSIX.6 | No | System security. | |
POSIX.7 | No | System administration. | |
POSIX.8 | No | Networking A. Transparent file access B. Protocol-independent network interface C. Remote Procedure Calls (RPC) D. Open system interconnect protocol-dependent application interfaces | |
POSIX.9 | Yes | FORTRAN language bindings to POSIX.1. | |
POSIX.10 | No | Super-computing Application Environment Profile (AEP). | |
POSIX.11 | No | Transaction Processing AEP. | |
POSIX.12 | No | Graphical user interface. | |