When choosing a Operating System the informed person would want to know it follows certain standards. The Portable Operating System Interface standard was created to ensure that Unix-like Operating Systems use applications that look and feel similar to those used on other POSIX compliant Operating Systems.
If an Operating System is POSIX compliant, you can be assure of the following:
It is an acceptable level of quality,
It will have the same look and feel as other products on the market, this makes training and support an easier task to source and implement,
It has industry input that has been built up over time and experience of other technical learning curves when building and supporting other operating systems.
The POSIX standard is maintained by the Portable Application Standards Committee (PASC) of the IEEE organisation. The standard is heavily influenced by Unix - and in the latest revision now merges with The Open Group's Base Specifications (LSB) which comprise the core of the Single Unix Specification.
The POSIX standard was developed so that people developing Operating Systems could reference one standard so as to ensure that different Operating Systems would be able to interoperate with each other. Linux is not completely compliant with POSIX, a draft document has been released by the Open Group detailing conflicts between POSIX and their Linux Standards Base (LSB). This can be viewed at: http://www.opengroup.org/personal/ajosey/tr28-07-2003.txt
The Open Group's LSB certification is another standard that has been set against which developers can test their products. Visit this page to find out more about this certification. The LSB is a standard created to ensure greater conformity between the different Linux Distributions, whilst the POSIX standard is meant to ensure greater conformity between all Unix-like operating Systems.
The Open Group is a trademark of The Open Group. Unix is a registered trademark of The Open Group in the US and other countries. POSIX is a registered trademark of the IEEE Inc. LSB is a trademark of the Free Standards Group.