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GNU Hurd
GNU Hurd is a collection of microkernel servers written as part of GNU, for the GNU Mach microkernel. It has been under development since 1990 by the GNU Project of the Free Software Foundation, designed as a replacement for the Unix kernel, and released as free software under the GNU General Public License. When the Linux kernel proved to be a viable solution, development of GNU Hurd slowed, at times alternating between stasis and renewed activity and interest. The Hurd's design consists of a set of protocols and server processes (or daemons, in Unix terminology) that run on the GNU Mach microkernel. The Hurd aims to surpass the Unix kernel in functionality, security, and stability, while remaining largely compatible with it. The GNU Project chose the multiserver microkernel for the operating system, due to perceived advantages over the traditional Unix monolithic kernel architecture, a view that had been advocated by some developers in the 1980s. Name and logo In December ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 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 in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley ( BSD), Microsoft (Xenix), Sun Microsystems ( SunOS/ Solaris), HP/ HPE ( HP-UX), and IBM ( AIX). The early versions of Unix—which are retrospectively referred to as " Research Unix"—ran on computers such as the PDP-11 and VAX; Unix was commonly used on minicomputers and mainframes from the 1970s onwards. It distinguished itself from its predecessors as the first portable operating system: almost the entire operating system is written in the C programming language (in 1973), which allows U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Text Editor
A text editor is a type of computer program that edits plain text. An example of such program is "notepad" software (e.g. Windows Notepad). Text editors are provided with operating systems and software development packages, and can be used to change files such as configuration files, documentation files and programming language source code. Plain text and rich text There are important differences between plain text (created and edited by text editors) and rich text (such as that created by word processors or desktop publishing software). Plain text exclusively consists of character representation. Each character is represented by a fixed-length sequence of one, two, or four bytes, or as a variable-length sequence of one to four bytes, in accordance to specific character encoding conventions, such as ASCII, ISO/IEC 2022, ISO/IEC 2022, Shift JIS, UTF-8, or UTF-16. These conventions define many printable characters, but also whitespace character, non-printing characters th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Stallman
Richard Matthew Stallman ( ; born March 16, 1953), also known by his initials, rms, is an American free software movement activist and programmer. He campaigns for software to be distributed in such a manner that its users have the freedom to use, study, distribute, and modify that software. Software which ensures these freedoms is termed free software. Stallman launched the GNU Project, founded the Free Software Foundation (FSF) in October 1985, developed the GNU Compiler Collection and GNU Emacs, and wrote all versions of the GNU General Public License. Stallman launched the GNU Project in September 1983 to write a Unix-like computer operating system composed entirely of free software. With that he also launched the free software movement. He has been the GNU project's lead architect and organizer, and developed a number of pieces of widely used GNU software including among others, the GNU Compiler Collection, GNU Debugger, and GNU Emacs text editor. Stallman pioneered the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inter-process Communication
In computer science, interprocess communication (IPC) is the sharing of data between running Process (computing), processes in a computer system. Mechanisms for IPC may be provided by an operating system. Applications which use IPC are often categorized as client–server model, clients and servers, where the client requests data and the server responds to client requests. Many applications are both clients and servers, as commonly seen in distributed computing. IPC is very important to the design process for microkernels and nanokernels, which reduce the number of functionalities provided by the kernel. Those functionalities are then obtained by communicating with servers via IPC, leading to a large increase in communication when compared to a regular monolithic kernel. IPC interfaces generally encompass variable analytic framework structures. These processes ensure compatibility between the multi-vector protocols upon which IPC models rely. An IPC mechanism is either Synchroni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wildebeest
Wildebeest ( , ,), also called gnu ( or ), are antelopes of the genus ''Connochaetes'' and native to Eastern and Southern Africa. They belong to the family Bovidae, which includes true antelopes, cattle, goats, sheep, and other even-toed horned ungulates. There are two species of wildebeest: the black wildebeest or white-tailed gnu (''C. gnou''), and the blue wildebeest or brindled gnu (''C. taurinus''). Fossil records suggest these two species diverged about one million years ago, resulting in a northern and a southern species. The blue wildebeest remained in its original range and changed very little from the ancestral species, while the black wildebeest changed more as adaptation to its open grassland habitat in the south. The most obvious ways of telling the two species apart are the differences in their colouring and in the way their horns are oriented. In East Africa, the blue wildebeest is the most abundant big-game species; some populations perform an annual mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herd
A herd is a social group of certain animals of the same species, either wild or domestic. The form of collective animal behavior associated with this is called '' herding''. These animals are known as gregarious animals. The term ''herd'' is generally applied to mammals, and most particularly to the grazing ungulates that classically display this behaviour. Different terms are used for similar groupings in other species; in the case of birds, for example, the word is '' flocking'', but ''flock'' may also be used for mammals, particularly sheep or goats. Large groups of carnivores are usually called '' packs'', and in nature a herd is classically subject to predation from pack hunters. Special collective nouns may be used for particular taxa (for example a flock of geese, if not in flight, is sometimes called a ''gaggle'') but for theoretical discussions of behavioural ecology, the generic term ''herd'' can be used for all such kinds of assemblage. The word ''herd'', a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homophone
A homophone () is a word that is pronounced the same as another word but differs in meaning or in spelling. The two words may be spelled the same, for example ''rose'' (flower) and ''rose'' (past tense of "rise"), or spelled differently, as in ''rain'', ''reign'', and ''rein''. The term ''homophone'' sometimes applies to units longer or shorter than words, for example a phrase, letter, or groups of letters which are pronounced the same as a counterpart. Any unit with this property is said to be ''homophonous'' (). Homophones that are spelled the same are both homographs and homonyms. For example, the word ''read'', in "He is well ''read''" and in "Yesterday, I ''read'' that book". Homophones that are spelled differently are also called heterographs, e.g. ''to'', ''too'', and ''two''. Wordplay and games Homophones are often used to create puns and to deceive the reader (as in crossword puzzles) or to suggest multiple meanings. The last usage is common in poetry and creat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recursive Acronym
A recursive acronym is an acronym that refers to itself, and appears most frequently in computer programming. The term was first used in print in 1979 in Douglas Hofstadter's book '' Gödel, Escher, Bach: An Eternal Golden Braid'', in which Hofstadter invents the acronym GOD, meaning "GOD Over Djinn", to help explain infinite series, and describes it as a recursive acronym. Other references followed, however the concept was used as early as 1968 in John Brunner's science fiction novel ''Stand on Zanzibar''. In the story, the acronym EPT (Education for a Particular Task) later morphed into "Eptification for Particular Task". Recursive acronyms typically form backwardly: either an existing ordinary acronym is given a new explanation of what the letters stand for, or a name is turned into an acronym by giving the letters an explanation of what they stand for, in each case with the first letter standing recursively for the whole acronym. Use in computing In computing, an early tra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mutual Recursion
In mathematics and computer science, mutual recursion is a form of recursion where two mathematical or computational objects, such as functions or datatypes, are defined in terms of each other. Mutual recursion is very common in functional programming and in some problem domains, such as recursive descent parsers, where the datatypes are naturally mutually recursive. Examples Datatypes The most important basic example of a datatype that can be defined by mutual recursion is a tree, which can be defined mutually recursively in terms of a forest (a list of trees). Symbolically: f: [1 ..., t[k t: v f A forest ''f'' consists of a list of trees, while a tree ''t'' consists of a pair of a value ''v'' and a forest ''f'' (its children). This definition is elegant and easy to work with abstractly (such as when proving theorems about properties of trees), as it expresses a tree in simple terms: a list of one type, and a pair of two types. Further, it matches many algorithms on trees, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monolithic Kernel
A monolithic kernel is an operating system software architecture, architecture with the entire operating system running in kernel space. The monolithic model differs from other architectures such as the microkernel in that it alone defines a high-level virtual interface over computer hardware. A set of primitives or system calls implement all operating system services such as Process (computing), process management, Concurrency (computer science), concurrency, and memory management. Device drivers can be added to the kernel as loadable kernel modules. Examples *Most BSD kernels **FreeBSD **OpenBSD **NetBSD *Linux kernel **Android (operating system), Android *Other Unix/Unix-like kernels **AIX **Oracle Solaris *MS-DOS **Windows 9x *OpenVMS *Palm OS (version ≤ 5.0) Loadable modules Modular operating systems such as OS-9 and most modern monolithic-kernel operating systems such as OpenVMS, Linux kernel, Linux, FreeBSD, NetBSD, DragonFly BSD, Oracle Solaris, Solaris, and AIX can d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daemon (computing)
In computing, a daemon is a program that runs as a background process, rather than being under the direct control of an interactive user. Customary convention is to name a daemon process with the letter ''d'' as a suffix to indicate that it's a daemon. For example, is a daemon that implements system logging facility, and is a daemon that serves incoming SSH connections. Even though the concept can apply to many computing systems, the term ''daemon'' is used almost exclusively in the context of Unix-based systems. In other contexts, different terms are used for the same concept. Systems often start daemons at boot time that will respond to network requests, hardware activity, or other programs by performing some task. Daemons such as cron may also perform defined tasks at scheduled times. Terminology In the context of computing, the word is generally pronounced either as or . The term was coined by the programmers at MIT's Project MAC. According to Fernando J. Cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
