POSIX stands for "Portable Operating System Interface" and defines a set of standards to provide compatibility between different computing platforms. The current version of the standard is IEEE 1003.1 2016 and can be accessed from the OpenGroup POSIX specification. Previous versions include POSIX 2004 and POSIX 1997. The POSIX 2016 edition is essentially POSIX 2008 plus errata (there was a POSIX 2013 release too).

POSIX defines various tools interfaces, commands and APIs for UNIX-like operating systems and others.

The following are considered to be within the scope of POSIX standardization:

  • System interface (functions, macros and external variables)
  • Command interpreter, or Shell (the sh utility)
  • Utilities (such as more, cat, ls)

Outside of POSIX scope:

  • DBMS Interfaces
  • Graphical Interfaces
  • Binary code portability