UNIX? Compatibility issues
Release Date : 20/12/89
In this paper we present areas where compatibility problems exist between various
UNIX systems, and examine how they affect the construction of portable code. We also look into the future directions of UNIX and more specifically the AT&T System V, release 4 and the graphical user interfaces (GUIs).
Keywords: UNIX, System V, BSD 4.3, compatibility
Most books on UNIX include an illustration depicting the evolution of the UNIX system from its early beginnings on the PDP8. These graphs usually include a great number of Unix-like systems that were mainly derived from Version 6 and Version 7 UNIX. Fortunately only three UNIX systems are important enough to warrant serious attention: System V Release 3.2 the current commercial AT&T offering, Version 9 UNIX, used internally by AT&T for research and development, and last but not least the 4.3 Berkeley Software Distribution UNIX which is widely used by universities and research centers all over the world.
AT&T is also ready to release the new version of System V (SysV-R4), but we haven't yet seen any commercially available products that use this system, (for more information on SysV-R4, see section 4) furthermore, Version 9 UNIX is not available outside AT&T. Thus, in this paper we will concentrate on System V Release 3.2 (SysV-R3.2) and the Berkeley UNIX (BSD 4.3).
Most UNIX vendors use the SysV-R3.2 on their products since this system has the support of AT&T. Nevertheless, BSD 4.3 has a great number of followers mainly because of its superior networking support and richer set of commands. Another point in favor of the Berkeley UNIX is that most computer science graduates are familiar with it and prefer it over the AT&T system.
Although the two systems are sufficiently different to cause untold suffering to
users that migrate from one to the other, most differences can be hidden from the user.
In fact most Sys V vendors have made efforts to bring the two systems closer. The two
? UNIX is a registered trademark of AT&T.
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