<P> The Unix - like family is a diverse group of operating systems, with several major sub-categories including System V, BSD, and Linux . The name "UNIX" is a trademark of The Open Group which licenses it for use with any operating system that has been shown to conform to their definitions . "UNIX - like" is commonly used to refer to the large set of operating systems which resemble the original UNIX . </P> <P> Unix - like systems run on a wide variety of computer architectures . They are used heavily for servers in business, as well as workstations in academic and engineering environments . Free UNIX variants, such as Linux and BSD, are popular in these areas . </P> <P> Four operating systems are certified by The Open Group (holder of the Unix trademark) as Unix . HP's HP - UX and IBM's AIX are both descendants of the original System V Unix and are designed to run only on their respective vendor's hardware . In contrast, Sun Microsystems's Solaris can run on multiple types of hardware, including x86 and Sparc servers, and PCs . Apple's macOS, a replacement for Apple's earlier (non-Unix) Mac OS, is a hybrid kernel - based BSD variant derived from NeXTSTEP, Mach, and FreeBSD . </P> <P> Unix interoperability was sought by establishing the POSIX standard . The POSIX standard can be applied to any operating system, although it was originally created for various Unix variants . </P>

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