The UNIX operating system originated from AT&T (now USL) in the early 1970's. Because UNIX was able to run on different hardware from different vendors, this encouraged developers to modify UNIX and distribute it as their own value-added version of UNIX. Separate UNIX traditions evolved as a result: USL's System V, Berkeley Standard Distribution (BSD, from the University of California, Berkeley), Xenix, etc.
Today, UNIX developers are trying to blend the different traditions back into a more standard version. (The ongoing work on POSIX, an international standard based on System V and BSD, is influencing this movement.) This quick reference describes two systems that offer what many people consider to be a "more standard" version of UNIX: System V Release 4 (SVR4) and Solaris 2.0.
SVR4, which was developed jointly by USL (a division of AT&T) and Sun Microsystems, has merged features from BSD and SVR3. This adds about two dozen BSD commands (plus some new SVR4 commands) to the basic UNIX command set. In addition, SVR4 provides a BSD Compatibility Package, a kind of "second string" command group. This package includes some of the most fundamental BSD commands, and its purpose is to help users of BSD-derived systems make the transition to SVR4.
Solaris 2.0 includes the SunOS 5.0 operating system plus additional features such as OpenWindows. SunOS 5.0, in turn, merges SunOS 4.1 and SVR4. Most of the new content comes from SVR4. As a result, Solaris 2.0 is based on SVR4 but contains additional BSD/SunOS features. To help in the transition from the old (largely BSD-based) SunOS, Solaris 2.0 provides the BSD/SunOS Compatibility Package and the Binary Compatibility Package.