What Does this 'POSIX' or 'POSIX 1003.2' Standard mean?    POSIX (Portable Open System in Unix) is a name originally coined by Richard Stallman for a family of open system standards based on Unix. There are a number of aspects of Unix under consideration for standardization, from the basic system services at the system call and C library level to applications and tools to system administration and management. Each area of standardization is assigned to a IEEE working group in the 1003 series. Thus, POSIX 1003.2 means Unis shell and utilities standard developed by IEEE Working Group 1003.2 (=POSIX.2). POSIX 1003.2 (POSIX.2) concentrates on the command interpreter interface and utility programs commonly executed from the command line or by other programs. An initial version of the standard has been approved and published by the IEEE, and work is currently underway to update it. A good example of POSIX-compliant shell is bash shell. Therefore, you can reasonably expect standard behaivoirs from any program compliant to POSIX.2 standard regardless of its platform and operating system.