IEEE Draft Standard for Information Technology-Portable Operating System Interface (POSIX®)--IEEE Draft Technical Standard: Base Specifications, Issue 7

POSIX.1-200x defines a standard operating system interface and environment, including a command interpreter (or "shell"), and common utility programs to support applications portability at the source code level. POSIX.1-200x is intended to be used by both application developers and system implementors and comprises four major components (each in an associated volume)