The difference between Unix and Linux.

When I asked, it was difficult for me to explain the difference of them strictly.


To understand the difference and history of Unix and Linux.

What is Unix and Linux

They are some of OS.

UnixAT&T(1968)CLI (&GUI, X-windows)Single UNIX SpecificationC, Assembly languagemac OS
LinuxUniversity of Helsinki (1991)GUI (& CLI)Linux Standard Base
C, Assembly languageOpen source, Unix-like, used in Android
WindowsMicrosoft (1985)CLI (& GUI)C, C++, Assembly language

Difference of Unix and Linux

Unix is a general term to express operating system that meets some conditions(Single UNIX Specification).

Linux is one of the Unix-like operating system. It is developed taking after Unix, but it is different OS. Linux has its source code and original kernel called Linux kernel.

Linux is open source in contrast to Unix. This is the

Similarities of Unix and Linux

Linux is  UNIX compatible operating system that meets POSIX. So they have similar interfaces. POSIX, Portable operating system interface, is API standard that define application interface programming of Unix and Unix-like OS. OS that meet POSIX have similar system calls, formats, structures of directories and files, processes and databases.

By combining Linux kernel and GNU software, a complete UNIX compatible operating system is available as free software.