For now, Linux is not POSIX-certified due to high costs, except for the two commercial Linux distributions Inspur K-UX [12] and Huawei EulerOS [6]. Instead, Linux is seen as being mostly POSIX-compliant.

Is Linux a Unix or POSIX?

POSIX defines set of standards for an operating system or a program. The goal is to write new software that is compatible with UNIX-like systems. For example a program runs on Linux is also can be compile and run on other UNIX-like systems like Solaris, HP-UX, and AIX etc..

Why isn’t Linux POSIX certified?

1 Answer. POSIX does not specify a kernel interface, so Linux is largely irrelevant. It does specify the system interface, various tools, and extensions to the C standard, which could exist on top of any kernel.