Unix (officially trademarked as UNIX, sometimes also written as Unix with small caps In typography, small capitals are uppercase (capital) characters set at the same height and weight as surrounding lowercase (small) letters or text figures. They are used in running text to prevent capitalized words from appearing too large on the page, and as a method of emphasis or distinctiveness for text alongside or instead of italics, or) is a computer operating system An operating system is the software on a computer that manages the way different programs use its hardware, and regulates the ways that a user controls the computer. Operating systems are found on almost any device that contains a computer with multiple programs—from cellular phones and video game consoles to supercomputers and web servers. Some originally developed in 1969 by a group of AT&T AT&T Corporation, originally the American Telephone & Telegraph Company, is an American telecommunications company that provides voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agencies. During its long history, AT&T was at times the world's largest telephone employees at Bell Labs Bell Laboratories is the research and development organization of Alcatel-Lucent and previously of the American Telephone & Telegraph Company (AT&T), including Ken Thompson Kenneth Lane Thompson , commonly referred to as Ken Thompson (or simply ken in hacker circles), is an American pioneer of computer science notable for his work with the B programming language and his shepherding of the Unix and Plan 9 operating systems, Dennis Ritchie Dennis MacAlistair Ritchie is an American computer scientist notable for his influence on C and other programming languages, and on operating systems such as Multics and Unix. He received the Turing Award in 1983 and the National Medal of Technology in 1998. Ritchie was the head of Lucent Technologies System Software Research Department when he, Brian Kernighan Brian Wilson Kernighan is a Canadian computer scientist who worked at Bell Labs alongside Unix creators Ken Thompson and Dennis Ritchie and contributed greatly to Unix and its school of thought. He is also coauthor of the AWK and AMPL programming languages. The 'K' of K&R C and the 'K' in AWK both stand for 'Kernighan'. Brian Kernighan is, Douglas McIlroy Malcolm Douglas McIlroy is a mathematician, engineer, and programmer. As of 2007 he is an Adjunct Professor of Computer Science at Dartmouth College. Dr. McIlroy is best known for having originally developed the Unix pipeline implementation, software componentry and several Unix tools, such as spell, diff, sort, join, graph, speak, and tr, and Joe Ossanna Joseph F. Ossanna , received his Bachelor of Engineering from Wayne State University, Detroit, Michigan, in 1952. He was a member of the Technical Staff of the Bell Telephone Laboratories in Murray Hill, New Jersey. He was actively engaged in the software design of Multics (Multiplexed Information and Computing Service), a general purpose. Today's Unix systems are split into various branches, developed over time by AT&T as well as various commercial vendors and non-profit A non-profit organization is an organization that does not distribute its surplus funds to owners or shareholders, but instead uses them to help pursue its goals. Examples of NPOs include charities (i.e. charitable organizations), trade unions, and public arts organizations. Most governments and government agencies meet this definition, but in organizations.
The Open Group The Open Group is an industry consortium to set vendor- and technology-neutral open standards for computing infrastructure. It was formed when X/Open merged with the Open Software Foundation in 1996. The Open Group is most famous as the certifying body for the UNIX trademark, in the past the group was best known for its publication of the Single, an industry standards consortium, owns the “Unix” trademark. Only systems fully compliant with and certified according to the Single UNIX Specification The Single UNIX Specification is the collective name of a family of standards for computer operating systems to qualify for the name "Unix". The SUS is developed and maintained by the Austin Group, based on earlier work by the IEEE and The Open Group are qualified to use the trademark; others may be called "Unix system-like" or "Unix-like 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" (though the Open Group disapproves of this term). However, the term "Unix" is often used informally to denote any operating system that closely resembles the trademarked system.
During the late 1970s and early 1980s, the influence of Unix in academic circles led to large-scale adoption of Unix (particularly of the BSD Berkeley Software Distribution is the UNIX operating system derivative developed and distributed by the Computer Systems Research Group (CSRG) of the University of California, Berkeley, from 1977 to 1995 variant, originating from the University of California, Berkeley The University of California, Berkeley , is a public research university located in Berkeley, California, United States. The oldest of the ten major campuses affiliated with the University of California, Berkeley offers some 300 undergraduate and graduate degree programs in a wide range of disciplines. The university occupies 6,651 acres (2,692 ha)) by commercial startups, the most notable of which are Solaris Oracle Solaris is a UNIX-based operating system introduced by Sun Microsystems in 1992 as the successor to SunOS, HP-UX HP-UX is Hewlett-Packard's proprietary implementation of the Unix operating system, based on System V (initially System III). It runs on the HP 9000 PA-RISC-based range of processors and HP Integrity systems that are based on Intel's Itanium-processors. HP-UX was also available for later Apollo/Domain systems, and earlier versions ran on the HP 900 and AIX AIX is the name given to a series of proprietary operating systems sold by IBM for several of its computer system platforms, based on UNIX System V with 4.3BSD-compatible extensions. Today, in addition to certified Unix systems such as those already mentioned, Unix-like 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 operating systems such as Linux Linux refers to the family of Unix-like computer operating systems using the Linux kernel. Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2009 it held a server market share and BSD descendants (FreeBSD FreeBSD is a free Unix-like operating system descended from AT&T UNIX via the Berkeley Software Distribution . It has been characterized as "the unknown giant among free operating systems". It is not a clone of UNIX, but works like UNIX, with UNIX-compliant internals and system APIs. FreeBSD is generally regarded as reliable and, NetBSD NetBSD is a freely available open source version of the Unix-derivative Berkeley Software Distribution computer operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. The NetBSD project is primarily focused on high quality design, stability and performance of, and OpenBSD OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995. The project is widely known for the developers' insistence on open source code and quality documentation,) are commonly encountered. The term "traditional Unix" may be used to describe a Unix or an operating system that has the characteristics of either Version 7 Unix Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix operating system. V7, released in 1979, was the last Bell Laboratories release to see widespread distribution before the commercialization of Unix by AT&T in the early 1980s. V7 was originally developed for Digital Equipment or UNIX System V Unix System V, commonly abbreviated SysV , is one of the versions of the Unix operating system. It was originally developed by American Telephone & Telegraph (AT&T) and first released in 1983. Four major versions of System V were released, termed Releases 1, 2, 3 and 4. System V Release 4, or SVR4, was commercially the most successful.
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Overview
Timeline of Unix variantsUnix operating systems are widely used in both servers In computing, a server is any combination of hardware or software designed to provide services to clients. When used alone, the term typically refers to a computer which may be running a server operating system, but is also used to refer to any software or dedicated hardware capable of providing services and workstations A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has also been used to refer to a mainframe computer terminal or a PC connected to a. The Unix environment and the client–server program model were essential elements in the development of the Internet The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks of local to global scope that are linked by a broad array of electronic and and the reshaping of computing as centered in networks Computer networking is the engineering discipline concerned with the communication between computer systems or devices. A computer network is any set of computers or devices connected to each other with the ability to exchange data. Computer networking is sometimes considered a sub-discipline of telecommunications, computer science, information rather than in individual computers.
Both Unix and the C programming language C is a general-purpose computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system 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. As a result, Unix became synonymous with "open systems Open systems are computer systems that provide some combination of interoperability, portability, and open software standards".
Unix was designed to be portable In computer science, porting is the process of adapting software so that an executable program can be created for a computing environment that is different from the one for which it was originally designed . The term is also used in a general way to refer to the changing of software/hardware to make them usable in different environments, multi-tasking In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for that task. Multitasking solves the problem by and multi-user Multi-user is a term that defines an operating system or application software that allows concurrent access by multiple users of a computer. Time-sharing systems are multi-user systems. Most batch processing systems for mainframe computers may also be considered "multi-user", to avoid leaving the CPU idle while it waits for I/O in a time-sharing Time-sharing is the sharing of a computing resource among many users by means of multiprogramming and multi-tasking. Its introduction in the 1960s, and emergence as the prominent model of computing in the 1970s, represents a major technological shift in the history of computing configuration. Unix systems are characterized by various concepts: the use of plain text In computing, plain text is the contents of an ordinary sequential file readable as textual material without much processing, usually opposed to formatted text for storing data; a hierarchical file system A file system is a method of storing and organizing computer files and their data. Essentially, it organizes these files into a database for the storage, organization, manipulation, and retrieval by the computer's operating system; treating devices and certain types of inter-process communication (IPC) as files; and the use of a large number of software tools A programming tool or software development tool is a program or application that software developers use to create, debug, maintain, or otherwise support other programs and applications. The term usually refers to relatively simple programs that can be combined together to accomplish a task, much as one might use multiple hand tools to fix a, small programs that can be strung together through a command line interpreter A command-line interpreter is a computer program that reads lines of text entered by a user and interprets them in the context of a given operating system or programming language using pipes In Unix-like computer operating systems , a pipeline is the original software pipeline: a set of processes chained by their standard streams, so that the output of each process (stdout) feeds directly as input (stdin) to the next one. Each connection is implemented by an anonymous pipe. Filter programs are often used in this configuration, as opposed to using a single monolithic program that includes all of the same functionality. These concepts are collectively known as the Unix philosophy The Unix philosophy is a set of cultural norms and philosophical approaches to developing software based on the experience of leading developers of the Unix operating system.
Under Unix, the "operating system" consists of many of these utilities along with the master control program, the kernel In computing, the kernel is the central component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources . Usually as a basic component of an operating system, a kernel can provide the lowest-level. The kernel provides services to start and stop programs, handles the file system A file system is a method of storing and organizing computer files and their data. Essentially, it organizes these files into a database for the storage, organization, manipulation, and retrieval by the computer's operating system and other common "low level" tasks that most programs share, and, perhaps most importantly, schedules access to hardware to avoid conflicts if two programs try to access the same resource or device simultaneously. To mediate such access, the kernel was given special rights on the system, leading to the division between user-space and kernel-space.
The microkernel In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system. These mechanisms include low-level address space management, thread management, and inter-process communication. As an operating system design approach, microkernels permit typical operating system 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 "normal" 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 computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons. (Although traditionally a button is typically round or square, modern mice have spring-loaded regions of their top, and in the 1980s non-blocking I/O and the set of inter-process communication Inter-process communication is a set of techniques for the exchange of data among multiple threads in one or more processes. Processes may be running on one or more computers connected by a network. IPC techniques are divided into methods for message passing, synchronization, shared memory, and remote procedure calls (RPC). The method of IPC used mechanisms was augmented (sockets, shared memory In computing, shared memory is memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies. Depending on context, programs may run on a single processor or on multiple separate processors. Using memory for communication inside a single program, for example among its, message queues, semaphores In computer science, a semaphore is a protected variable or abstract data type which constitutes the classic method for restricting access to shared resources such as shared memory in a parallel programming environment. A counting semaphore is a counter for a set of available resources, rather than a locked/unlocked flag of a single resource. It), and functionalities such as network protocols were moved out of the kernel.
History
In the 1960s, Massachusetts Institute of Technology The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological research. MIT is one of two private land-grant universities[b] and is also a sea-grant and space-, AT&T Bell Labs Bell Laboratories is the research and development organization of Alcatel-Lucent and previously of the American Telephone & Telegraph Company (AT&T), and General Electric developed an experimental operating system called Multics for the GE-645 mainframe.[1] Multics was highly innovative, but had many problems.
Bell Labs, frustrated by the size and complexity of Multics but not the aims, slowly pulled out of the project. Their last researchers to leave Multics, Ken Thompson, Dennis Ritchie, M. D. McIlroy, and J. F. Ossanna,[2] decided to redo the work on a much smaller scale. At the time, Ritchie says "What we wanted to preserve was not just a good environment in which to do programming, but a system around which a fellowship could form. We knew from experience that the essence of communal computing, as supplied by remote-access, time-shared machines, is not just to type programs into a terminal instead of a keypunch, but to encourage close communication."[2]
While Ken Thompson still had access to the Multics environment, he wrote simulations for the new file and paging system on it. He also programmed a game called Space Travel, but the game needed a more efficient and less expensive machine to run on, and eventually a little-used PDP-7 at Bell Labs fit the bill.[3] On this PDP7, a team of Bell Labs researchers led by Thompson and Ritchie, including Rudd Canaday, developed a hierarchical file system, the notions of computer processes and device files, a command-line interpreter, and some small utility programs.[2]
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Wed, 01 Sep 2010 18:01:40 GMT+00:00
InfoGrok Job Description An urgent need has come about for an experienced technical consultant to work as part of the team involved in a Unix Utilisation ...
the oracle
Fri, 13 Aug 2010 18:23:24 GM
The idea that Windows could be as secure as . Unix. /Linux is a silly one, but Microsoft insists upon continuing the charade with puffing about the security of.
