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Unix (all-caps UNIX for the trademark) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, developed in the 1970s at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties from the late 1970s, leading to a variety of both academic and commercial variants of Unix from vendors such as the University of California, Berkeley (BSD), Microsoft (Xenix), IBM (AIX) and Sun Microsystems (Solaris). AT&T finally sold its rights in Unix to Novell in the early 1990s, which then sold its Unix business to the Santa Cruz Operation (SCO) in 1995,〔http://www.novell.com/news/press/archive/1995/12/pr95274.html〕 but the UNIX trademark passed to the industry standards consortium The Open Group, which allows the use of the mark for certified operating systems compliant with the Single UNIX Specification (SUS). Among these is Apple's OS X,〔(Apple Inc. - UNIX 03 ) Register of Certified Products, The Open Group〕 which is the Unix version with the largest installed base as of 2014. From the power user's or programmer's perspective, Unix systems are characterized by a modular design that is sometimes called the "Unix philosophy", meaning that the operating system provides a set of simple tools that each perform a limited, well-defined function, with a unified filesystem as the main means of communication〔 and a shell scripting and command language to combine the tools to perform complex workflows. Aside from the modular design, Unix also distinguishes itself from its predecessors as the first portable operating system: almost the entire operating system is written in the C programming language that allowed Unix to reach numerous platforms. Many clones of Unix have arisen over the years, of which Linux is the most popular, having overtaken the popularity of SUS-certified Unices on server platforms since its inception in the early 1990s. == Overview == Originally, Unix was meant to be a programmer's workbench to be used for developing software to be run on multiple platforms, more than to be used to run application software.〔(【引用サイトリンク】url=https://archive.org/stream/Whole_Earth_Software_Catalog_1984_Point/Whole_Earth_Software_Catalog_1984_Point_djvu.txt )〕 The system grew larger as the operating system started spreading in the academic circle, as users added their own tools to the system and shared them with colleagues. Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration. Unix systems are characterized by various concepts: the use of plain text for storing data; a hierarchical file system; treating devices and certain types of inter-process communication (IPC) as files; and the use of a large number of software tools, small programs that can be strung together through a command-line interpreter using pipes, as opposed to using a single monolithic program that includes all of the same functionality. These concepts are collectively known as the "Unix philosophy". Brian Kernighan and Rob Pike summarize this in ''The Unix Programming Environment'' as "the idea that the power of a system comes more from the relationships among programs than from the programs themselves".〔Kernighan, Brian W. Pike, Rob. ''The UNIX Programming Environment.'' 1984. viii〕 By the early 1980s users began seeing Unix as a potential universal operating system, suitable for computers of all sizes.〔(【引用サイトリンク】title=Tandy/Radio Shack Book: Whole Earth Software Catalog )〕 Unix operating systems are widely used in servers, workstations, and mobile devices. The Unix environment and the client–server program model were essential elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers. Both Unix and the C programming language were developed by AT&T and distributed to government and academic institutions, which led to both being ported to a wider variety of machine families than any other operating system. Under Unix, the operating system consists of many utilities along with the master control program, the kernel. The kernel provides services to start and stop programs, handles the file system and other common "low-level" tasks that most programs share, and schedules access to avoid conflicts when programs try to access the same resource or device simultaneously. To mediate such access, the kernel has special rights, reflected in the division between user space and kernel space. The microkernel concept was introduced in an effort to reverse the trend towards larger kernels and return to a system in which most tasks were completed by smaller utilities. In an era when a standard computer consisted of a hard disk for storage and a data terminal for input and output (I/O), the Unix file model worked quite well, as most I/O was linear. However, modern systems include networking and other new devices. As graphical user interfaces developed, the file model proved inadequate to the task of handling asynchronous events such as those generated by a mouse. In the 1980s, non-blocking I/O and the set of inter-process communication mechanisms were augmented with Unix domain sockets, shared memory, message queues, and semaphores. In microkernel implementations, functions such as network protocols could be moved out of the kernel, while conventional (monolithic) Unix implementations have network protocol stacks as part of the kernel. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Unix」の詳細全文を読む スポンサード リンク
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