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Single UNIX Specification
The Single UNIX Specification (SUS) is a standard for computer operating systems, compliance with which is required to qualify for using the "UNIX" trademark. The standard specifies programming interfaces for the C language, a command-line shell, and user commands. The core specifications of the SUS known as ''Base Specifications'' are developed and maintained by the Austin Group, which is a joint working group of IEEE, ISO/IEC JTC 1/SC 22/WG 15 and The Open Group. If an operating system is submitted to The Open Group for certification and passes conformance tests, then it is deemed to be compliant with a UNIX standard such as UNIX 98 or UNIX 03. Very few BSD and Linux-based operating systems are submitted for compliance with the Single UNIX Specification, although system developers generally aim for compliance with POSIX standards, which form the core of the Single UNIX Specification. The latest SUS consists of two parts: the ''base specifications'' technically iden ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Computer
A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic sets of operations known as Computer program, ''programs'', which enable computers to perform a wide range of tasks. The term computer system may refer to a nominally complete computer that includes the Computer hardware, hardware, operating system, software, and peripheral equipment needed and used for full operation; or to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of Programmable logic controller, industrial and Consumer electronics, consumer products use computers as control systems, including simple special-purpose devices like microwave ovens and remote controls, and factory devices like industrial robots. Computers are at the core of general-purpose devices ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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X/Open
X/Open group (also known as the Open Group for Unix Systems and incorporated in 1987 as X/Open Company, Ltd.) was a consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote open standards in the field of information technology. More specifically, the original aim was to define a single specification for operating systems derived from UNIX, to increase the interoperability of applications and reduce the cost of porting software. Its original members were Bull, ICL, Siemens, Olivetti, and Nixdorf—a group sometimes referred to as BISON. Philips and Ericsson joined in 1985, at which point the name X/Open was adopted. The group published its specifications as X/Open Portability Guide, starting with Issue 1 in 1985, and later as ''X/Open CAE Specification''. In 1987, X/Open was incorporated as X/Open Company, Ltd. By March 1988, X/Open grew to 13 members: AT&T, Digital, Hewlett-Packard, Sun Microsystems, Unisys, NCR, Olivetti, Bull, Ericsso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Echo (command)
echo is shell command that writes input text to standard output. It is available in many operating system and shells. It is often used in a shell script to log status, provide feedback to the user and for debugging. For an interactive session, output by default displays on the terminal screen, but output can be re-directed to a file or piped to another process. Many shells implement echo as a builtin command rather than an external application as are many other commands. Multiple, incompatible implementations of echo exist in different shells. Some expand escape sequences by default; some do not; some accept options; some do not. The POSIX specification leaves the behavior unspecified if the first argument is -n or any argument contains backslash characters while the Unix specification (XSI option in POSIX) mandates the expansion of some sequences and does not allow any option processing. In practice, many echo implementations are not compliant in the default environm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Korn Shell
KornShell (ksh) is a Unix shell which was developed by David Korn at Bell Labs in the early 1980s and announced at USENIX on July 14, 1983. The initial development was based on Bourne shell source code. Other early contributors were Bell Labs developers Mike Veach and Pat Sullivan, who wrote the Emacs and vi-style line editing modes' code, respectively. KornShell is backward-compatible with the Bourne shell and includes many features of the C shell, inspired by the requests of Bell Labs users. Features KornShell complies with POSIX.2, Shell and Utilities, Command Interpreter (IEEE Std 1003.2-1992.) Major differences between KornShell and the traditional Bourne shell include: * job control, command aliasing, and command history designed after the corresponding C shell features; job control was added to the Bourne Shell in 1989 * a choice of three command line editing styles based on vi, Emacs, and Gosling Emacs * associative arrays and built-in floating-point arithm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bourne Shell
The Bourne shell (sh) is a shell command-line interpreter for computer operating systems. It first appeared on Version 7 Unix, as its default shell. Unix-like systems continue to have /bin/sh—which will be the Bourne shell, or a symbolic link or hard link to a compatible shell—even when other shells are used by most users. The Bourne shell was once standard on all branded Unix systems, although historically BSD-based systems had many scripts written in csh. As the basis of POSIX sh syntax, Bourne shell scripts can typically be run with Bash or dash on Linux or other Unix-like systems; Bash itself is a free clone of Bourne. History Origins Work on the Bourne shell initially started in 1976. Developed by Stephen Bourne at Bell Labs, it was a replacement for the Thompson shell, whose executable file had the same name—sh. The Bourne shell was also preceded by the Mashey shell. Bourne was released in 1979 in the Version 7 Unix release distributed to colleges and univ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Library (computing)
In computing, a library is a collection of System resource, resources that can be leveraged during software development to implement a computer program. Commonly, a library consists of executable code such as compiled function (computer science), functions and Class (computer programming), classes, or a library can be a collection of source code. A resource library may contain data such as images and Text string, text. A library can be used by multiple, independent consumers (programs and other libraries). This differs from resources defined in a program which can usually only be used by that program. When a consumer uses a library resource, it gains the value of the library without having to implement it itself. Libraries encourage software reuse in a Modular programming, modular fashion. Libraries can use other libraries resulting in a hierarchy of libraries in a program. When writing code that uses a library, a programmer only needs to know how to use it not its internal d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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System Call
In computing, a system call (syscall) is the programmatic way in which a computer program requests a service from the operating system on which it is executed. This may include hardware-related services (for example, accessing a hard disk drive or accessing the device's camera), creation and execution of new processes, and communication with integral kernel services such as process scheduling. System calls provide an essential interface between a process and the operating system. In most systems, system calls can only be made from userspace processes, while in some systems, OS/360 and successors for example, privileged system code also issues system calls. For embedded systems, system calls typically do not change the privilege mode of the CPU. Privileges The architecture of most modern processors, with the exception of some embedded systems, involves a security model. For example, the '' rings'' model specifies multiple privilege levels under which software may be e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bourne Shell
The Bourne shell (sh) is a shell command-line interpreter for computer operating systems. It first appeared on Version 7 Unix, as its default shell. Unix-like systems continue to have /bin/sh—which will be the Bourne shell, or a symbolic link or hard link to a compatible shell—even when other shells are used by most users. The Bourne shell was once standard on all branded Unix systems, although historically BSD-based systems had many scripts written in csh. As the basis of POSIX sh syntax, Bourne shell scripts can typically be run with Bash or dash on Linux or other Unix-like systems; Bash itself is a free clone of Bourne. History Origins Work on the Bourne shell initially started in 1976. Developed by Stephen Bourne at Bell Labs, it was a replacement for the Thompson shell, whose executable file had the same name—sh. The Bourne shell was also preceded by the Mashey shell. Bourne was released in 1979 in the Version 7 Unix release distributed to colleges and univ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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C Header File
An include directive instructs a text file processor to replace the directive text with the content of a specified file. The act of including may be logical in nature. The processor may simply process the include file content at the location of the directive without creating a combined file. Different processors may use different syntax. The C preprocessor (used with C, C++ and in other contexts) defines an include directive as a line that starts #include and is followed by a file specification. COBOL defines an include directive indicated by copy in order to include a copybook. Generally, for C/C++ the include directive is used to include a header file, but can include any file. Although relatively uncommon, it is sometimes used to include a body file such as a .c file. The include directive can support encapsulation and reuse. Different parts of a system can be segregated into logical groupings yet rely on one another via file inclusion. C and C++ are designed to leverage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Research Unix
Research Unix refers to the early versions of the Unix operating system for DEC PDP-7, PDP-11, VAX and Interdata 7/32 and 8/32 computers, developed in the Bell Labs Computing Sciences Research Center (CSRC). The term ''Research Unix'' first appeared in the Bell System Technical Journal (Vol. 57, No. 6, Part 2 July/August 1978) to distinguish it from other versions internal to Bell Labs (such as PWB/UNIX and MERT) whose code-base had diverged from the primary CSRC version. However, that term was little-used until Version 8 Unix (1985), but has been retroactively applied to earlier versions as well. Prior to V8, the operating system was most commonly called simply UNIX (in caps) or the UNIX Time-Sharing System. Ancient UNIX is any early release of the Unix code base prior to Unix System III, particularly the Research Unix releases prior to and including Version 7 (the base for UNIX/32V as well as later developments of AT&T Unix). History AT&T licensed Version 5 to ed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Version 7 Unix
Version 7 Unix, also called Seventh Edition 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 Corporation in the early 1980s. V7 was originally developed for Digital Equipment Corporation's PDP-11 minicomputers and was later ported to other platforms. Overview Unix versions from Bell Labs were designated by the edition of the user's manual with which they were accompanied. Released in 1979, the Seventh Edition was preceded by Sixth Edition, which was the first version licensed to commercial users. Development of the Research Unix line continued with the Eighth Edition, which incorporated development from 4.1BSD, through the Tenth Edition, after which the Bell Labs researchers concentrated on developing Plan 9. V7 was the first readily portable version of Unix. As this was the era of minicompute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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The GNU Project
The GNU Project ( ) is a free software, mass collaboration project announced by Richard Stallman on September 27, 1983. Its goal is to give computer users freedom and control in their use of their computers and computing devices by collaboratively developing and publishing software that gives everyone the rights to freely run the software, copy and distribute it, study it, and modify it. GNU software grants these rights in its license. In order to ensure that the ''entire'' software of a computer grants its users all freedom rights (use, share, study, modify), even the most fundamental and important part, the operating system (including all its numerous utility programs) needed to be free software. Stallman decided to call this operating system ''GNU'' (a recursive acronym meaning "''GNU's not Unix!''"), basing its design on that of Unix, a proprietary operating system. According to its manifesto, the founding goal of the project was to build a free operating system, and if p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |