How does the POSIX.1 standard compare to the Linux Standard Base?
The POSIX.1 standard specifies application programming interfaces (APIs) at the source level, and is about source code portability. Its neither a code implementation nor an operating system, but a stable definition of a programming interface that those systems supporting the specification guarantee to provide to the application programmer. Efforts such as the Linux Standard Base, and similarly the iBCS2 for x86 implementations of System V, are primarily about binary portability and define a specific binary implementation of an interface to operating system services. In general they build upon the foundations of the POSIX standard. Two white papers with further information on this topic are available at: http://www.opengroup.org/platform/single_unix_specification/doc.tpl?gdid=9045, http://www.opengroup.org/platform/single_unix_specification/doc.tpl?gdid=9634.
