Information AboutUnix-like |
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A Unix-like Operating System is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification . The term can include Free Software / Open Source operating systems inspired by Bell Labs’ Unix or designed to emulate its features, commercial and proprietary work-alikes, and even versions based on the licensed UNIX source code (which may be deemed so “Unix-like” that they are certified to bear the “UNIX” trademark). There is no formal standard for defining the term, and some difference of opinion is possible as to whether a certain OS is “Unix-like” or not. THE TERM “UNIX-LIKE” AND THE UNIX TRADEMARK The Open Group owns the UNIX® Trademark and administers the Single UNIX Specification, with the “UNIX” name being used as a Certification Mark . They do not approve of the construction “Unix-like”, and consider it misuse of their trademark. Their guidelines require “UNIX” to be presented in uppercase or otherwise distinguished from the surrounding text, strongly encourage using it as a branding adjective for a generic word such as “system”, and discourage its use in hyphenated phrases. The closest phrase they consider correct is “UNIX system-like”.http://www.opengroup.org/tm-guidelines.htm
As of 2007 there is an active legal battle between court documents indicate that Gray’s legal team is seeking for the Open Group to provide documentation for their trademark claim. CATEGORIES Dennis Ritchie , one of the original creators of UNIX, has expressed his opinion that Unix-like systems such as Linux are De Facto UNIX systems. Eric S. Raymond has suggested that there are three kinds of Unix-like systems:
DEVELOPMENT OF UNIX-LIKE SYSTEMS “Unix-like” systems started to appear in the late ’70s and early ’80s. Many Proprietary versions, such as Idris (1978), Coherent (1983), and UniFlex (1985), aimed to provide businesses with the functionality available to academic users of UNIX. When AT&T later allowed commercial licensing of UNIX in the 1980s, a variety of proprietary systems were developed based on it, including AIX , HP-UX , IRIX , Solaris , Tru64 , Ultrix , and Xenix . These largely displaced the proprietary clones. Growing incompatibility between these systems led to the creation of interoperability standards, including POSIX and the Single UNIX Specification . Meanwhile, the GNU Project was launched in 1983 with the goal of making GNU , an operating system which all computer users could freely use, study, modify, and redistribute. Various “Unix-like” operating systems developed alongside GNU, frequently sharing substantial components with it (leading to some disagreement about whether they should be called “GNU” or not). These primarily served as low-cost and unrestricted substitutes for UNIX, and include 4.4BSD , Linux, and Minix. Some of these have in turn been the basis for commercial “Unix-like” systems, such as BSD/OS and Mac OS X . Notably, the next release of Mac OS X, Leopard, is certified under the Single UNIX Specification. The various BSD systems are notable in that they are in fact descendants of UNIX, developed by the University of California at Berkeley with UNIX source code from Bell Labs. However, the BSD code base has evolved since then, replacing all of the AT&T code. Since these operating systems are not certified as compliant with the Single UNIX Specification, they are referred to as "UNIX-'like'". CURRENT EXAMPLES Free software / open source Most Free / Open-source Unix-like systems do not seek UNIX branding for their product even if fully or mostly conformant; the costs for certification (especially given frequent release cycles) are generally considered prohibitive. The term Freenix is sometimes used to refer to such systems. Components are often shared between systems, with hybrids possible.
Free of charge & closed source Proprietary
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