Too Long; Didn't Read
POSIX is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. Most of the commands available on Linux/Unix platform are common & works in a similar way. POSIX standard provides a standard way to communicate with Operating System. There are different variants of Unix (IBM AIX, Sun Solaris, BSD Unix … ) and Linux (Red Hat, Ubuntu, Suse … ) are available in the market and POSIX provides standard for all of them.