UNIX System V

The first UNIX version that standardised most of the UNIX elements. It was developed by AT&T; and first released in 1989. It was an enhancement over AT&T's first commercial UNIX called System III. Traditionally, System V has been considered one of the two major "flavors" of UNIX, the other being BSD. However, with the advent of UNIX implementations developed from neither code base, such as Linux and QNX, this generalisation is not as accurate as it once was, and in any case standardisation efforts such as POSIX are tending to reduce the differences between implementations.