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Job Control (Unix)
In Unix and Unix-like operating systems, job control refers to control of jobs by a shell, especially interactively, where a "job" is a shell's representation for a process group. Basic job control features are the suspending, resuming, or terminating of all processes in the job/process group; more advanced features can be performed by sending signals to the job. Job control is of particular interest in Unix due to its multiprocessing, and should be distinguished from job control generally, which is frequently applied to sequential execution (batch processing). Overview When using Unix or Unix-like operating systems via a terminal (or terminal emulator), a user will initially only have a single process running, their interactive shell (it may or may not be a login shell). Most tasks (directory listing, editing files, etc.) can easily be accomplished by letting the program take control of the terminal and returning control to the shell when the program exits – formally, by atta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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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] |
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Less (Unix)
less is a terminal pager Computer program, program on Unix, Microsoft Windows, Windows, and Unix-like systems used to view (but not change) the contents of a text file one screen at a time. It is similar to , but has the extended capability of allowing both forward and backward navigation through the file. Unlike most Unix text editors/viewers, does not need to read the entire file before starting, allowing for immediate viewing regardless of file size. History Mark Nudelman initially wrote less during 1983–85, in the need of a version of More (command), more able to do backward scrolling of the displayed text. The name came from the joke of doing "backwards more." Originally, less was developed for Unix, but it has been ported to a number of other operating systems, including MS-DOS, Microsoft Windows, OS/2, and OS-9, as well as Unix-like systems such as Linux. It is still maintained today by Nudelman. To help remember the difference between less and more, a common joke is to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Logout
In computer security, logging in (or logging on, signing in, or signing on) is the process by which an individual gains access to a computer system or program by identifying and authenticating themselves. Typically, user credentials consist of a username and a password. These credentials themselves are sometimes referred to as ''a'' login. Modern secure systems often require a second factor, such as email or SMS confirmation for extra security. Social login allows a user to use an existing cell phone number, or user credentials from another email or social networking service to sign in or create an account on a new website. When access is no longer needed, the user can log out, log off, sign out or sign off. Procedure Logging in is usually used to enter a specific page, website, platform or application, which trespassers cannot see. Once the user is logged in, the login token may be used to track what actions the user has taken while connected to the site. Loggin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Login Session
In computing, a login session is the period of activity between a user logging in and logging out of a (multi-user) system. On Unix and Unix-like operating systems, a login session takes one of two main forms: * When a textual user interface is used, a login session is represented as a kernel session — a collection of process groups with the logout action managed by a session leader. * Where an X display manager is employed, a login session is considered to be the lifetime of a designated user process that the display manager invokes. On Windows NT-based systems, login sessions are maintained by the kernel and control of them is overseen by the Local Security Authority Subsystem Service (LSA). winlogon responds to the secure attention key, it requests the LSA to create login sessions on login, and terminates all of the processes belonging to a login session on logout. See also * Booting process of Windows NT * Architecture of Windows NT * Booting * Master boot recor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Pipeline (Unix)
In Unix-like computer operating systems, a pipeline is a mechanism for inter-process communication using message passing. A pipeline is a set of process (computing), processes chained together by their standard streams, so that the output text of each process (''stdout'') is passed directly as input (''stdin'') to the next one. The second process is started as the first process is still executing, and they are executed concurrency (computer science), concurrently. The concept of pipelines was championed by Douglas McIlroy at Unix's ancestral home of Bell Labs, during the development of Unix, shaping its Unix philosophy, toolbox philosophy. It is named by analogy to a physical pipeline transport, pipeline. A key feature of these pipelines is their "hiding of internals". This in turn allows for more clarity and simplicity in the system. The pipes in the pipeline are anonymous pipes (as opposed to named pipes), where data written by one process is buffered by the operating system un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Wait (command)
In Unix shells, wait is a command which pauses until execution of a background process has ended. Usage wait ... where n... is a list of pids or job IDs of a currently executing background process (job). If no ids are provided, the command waits until all jobs known to the invoking shell have terminated. wait normally returns the exit status of the last job which terminated. It may also return 127 in the event that n specifies a non-existent job or zero if there were no jobs to wait for. Because wait needs to be aware of the job table of the current shell execution environment. Under the POSIX specifications it is required to be a shell builtin. Example This command can be useful where part of a script can execute in parallel to implement a barrier where an upcoming section depends on the successful completion of the preceding sections. The following example will fetch the src/ directory from a machine named iona using rsync rsync (remote sync) is a utility for ... [...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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Bell Labs
Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the company operates several laboratories in the United States and around the world. As a former subsidiary of the American Telephone and Telegraph Company (AT&T), Bell Labs and its researchers have been credited with the development of radio astronomy, the transistor, the laser, the photovoltaic cell, the charge-coupled device (CCD), information theory, the Unix operating system, and the programming languages B (programming language), B, C (programming language), C, C++, S (programming language), S, SNOBOL, AWK, AMPL, and others, throughout the 20th century. Eleven Nobel Prizes and five Turing Awards have been awarded for work completed at Bell Laboratories. Bell Labs had its origin in the complex corporate organization of the Bell System telepho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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KornShell
KornShell (ksh) is a Unix shell which was developed by David Korn (computer scientist), David Korn at Bell Labs in the early 1980s and announced at USENIX Annual Technical Conference, 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 (text editor), 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#POSIX.2, POSIX.2, Shell and Utilities, Command Interpreter (IEEE Std 1003.2-1992.) Major differences between KornShell and the traditional Bourne shell include: * Job control (Unix), job control, alias (command), command aliasing, and command history designed after the corresponding C shell features; job control was added to the Bourne Shell in 1989 * a choice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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IIASA
The International Institute for Applied Systems Analysis (IIASA) is an independent International research institute located in Laxenburg, near Vienna in Austria, founded as an East-West scientific cooperation initiative during the Cold War. Through its research programs and initiatives, the institute conducts policy-oriented interdisciplinary research into issues too large or complex to be solved by a single country or academic discipline. These include climate change, energy security, population aging, and sustainable development. The results of IIASA research and the expertise of its researchers are made available to policymakers worldwide to help them make informed and evidence-based policies. Organization Nearly 500 researchers from 50 countries currently work with the institute. IIASA's international and interdisciplinary network includes staff, alumni, member communities, collaborators, diplomatic partners, and visiting fellows. Hans Joachim "John" Schellnhuber is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bill Joy
William Nelson Joy (born November 8, 1954) is an American computer engineer and venture capitalist. He co-founded Sun Microsystems in 1982 along with Scott McNealy, Vinod Khosla, and Andy Bechtolsheim, and served as Chief Scientist and CTO at the company until 2003. He played an integral role in the early development of BSD UNIX while being a graduate student at Berkeley, and he is the original author of the vi text editor. He also wrote the 2000 essay " Why The Future Doesn't Need Us", in which he expressed deep concerns over the development of modern technologies. Joy was elected a member of the National Academy of Engineering (1999) for contributions to operating systems and networking software. Early career Joy was born in the Detroit suburb of Farmington Hills, Michigan, to William Joy, a school vice-principal and counselor, and Ruth Joy. He earned a Bachelor of Science in electrical engineering from the University of Michigan and a Master of Science in electrical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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C Shell
The C shell (csh or the improved version, tcsh) is a Unix shell created by Bill Joy while he was a graduate student at University of California, Berkeley in the late 1970s. It has been widely distributed, beginning with the 2BSD release of the Berkeley Software Distribution (BSD) which Joy first distributed in 1978. Other early contributors to the ideas or the code were Michael Ubell, Eric Allman, Mike O'Brien and Jim Kulp. The C shell is a command processor which is typically run in a text window, allowing the user to type and execute commands. The C shell can also read commands from a file, called a script. Like all Unix shells, it supports filename wildcarding, piping, here documents, command substitution, variables and control structures for condition-testing and iteration. What differentiated the C shell from others, especially in the 1980s, were its interactive features and overall style. Its new features made it easier and faster to use. The overall style of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |