Almquist Shell
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Almquist Shell
Almquist shell (also known as A Shell, ash and sh) is a lightweight Unix shell originally written by Kenneth Almquist in the late 1980s. Initially a clone of the System V.4 variant of the Bourne shell, it replaced the original Bourne shell in the BSD versions of Unix released in the early 1990s. History ash was first released via a posting to the Usenet news group, approved and moderated by Rich Salz on 30 May 1989. It was described as "a reimplementation of the System V shell ithmost features of that shell, plus some additions". Fast, small, and virtually compatible with the POSIX standard's specification of the Unix shell, ash did not provide line editing or command history mechanisms, because Almquist felt that such functionality should be moved into the terminal driver. However, modern variants support it. The following is extracted from the ash package information from Slackware v14: Myriad forks have been produced from the original ash release. These derivatives o ...
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C (programming Language)
C (''pronounced'' '' – like the letter c'') is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted Central processing unit, CPUs. It has found lasting use in operating systems code (especially in Kernel (operating system), kernels), device drivers, and protocol stacks, but its use in application software has been decreasing. C is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems. A successor to the programming language B (programming language), B, C was originally developed at Bell Labs by Ritchie between 1972 and 1973 to construct utilities running on Unix. It was applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity. It has become one of the most widely used programming langu ...
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Bash (Unix Shell)
In computing, Bash (short for "''Bourne Again SHell''") is an interactive command interpreter and command programming language developed for UNIX-like operating systems. Created in 1989 by Brian Fox for the GNU Project, it is supported by the Free Software Foundation and designed as a 100% free alternative for the Bourne shell (sh) and other proprietary Unix shells. Since its inception, Bash has gained widespread adoption and is commonly used as the default login shell for numerous Linux distributions. It holds historical significance as one of the earliest programs ported to Linux by Linus Torvalds, alongside the GNU Compiler ( GCC). It is available on nearly all modern operating systems, making it a versatile tool in various computing environments. As a command-line interface (CLI), Bash operates within a terminal emulator, or text window, where users input commands to execute various tasks. It also supports the execution of commands from files, known as shell scripts, f ...
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GNU GPL
The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first copyleft license available for general use. It was originally written by Richard Stallman, the founder of the Free Software Foundation (FSF), for the GNU Project. The license grants the recipients of a computer program the rights of the Free Software Definition. The licenses in the GPL series are all copyleft licenses, which means that any derivative work must be distributed under the same or equivalent license terms. The GPL is more restrictive than the GNU Lesser General Public License, and even more distinct from the more widely used permissive software licenses such as BSD, MIT, and Apache. Historically, the GPL license family has been one of the most popular software licenses in the free and open-source software (FOSS) domain. Promi ...
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BSD Licenses
BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft licenses, which have share-alike requirements. The original BSD license was used for its namesake, the Berkeley Software Distribution (BSD), a Unix-like operating system. The original version has since been revised, and its descendants are referred to as modified BSD licenses. BSD is both a license and a class of license (generally referred to as BSD-like). The modified BSD license (in wide use today) is very similar to the license originally used for the BSD version of Unix. The BSD license is a simple license that merely requires that all code retain the BSD license notice if redistributed in source code format, or reproduce the notice if redistributed in binary format. The BSD license (unlike some other licenses e.g. GPL) does not require that source code be distributed at all. Terms In addition to ...
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Android (operating System)
Android is an operating system based on a modified version of the Linux kernel and other open-source software, open-source software, designed primarily for touchscreen-based mobile devices such as smartphones and tablet computer, tablets. Android has historically been developed by a consortium of developers known as the Open Handset Alliance, but its most widely used version is primarily developed by Google. First released in 2008, Android is the world's Usage share of operating systems, most widely used operating system; the latest version, released on June 10, 2025, is Android 16. At its core, the operating system is known as the Android Open Source Project (AOSP) and is free and open-source software (FOSS) primarily licensed under the Apache License. However, most devices run the proprietary software, proprietary Android version developed by Google, which ships with additional proprietary closed-source software pre-installed, most notably Google Mobile Services (GMS), which ...
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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 ...
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Android Ice Cream Sandwich
Android Ice Cream Sandwich (or Android 4.0) is the fourth major version of the Android mobile operating system developed by Google. Unveiled on October 19, 2011, Android 4.0 built upon the significant changes made by the tablet-only release Android Honeycomb, in an effort to create a unified platform for both smartphones and tablets. The first phone with Android Ice Cream Sandwich was Samsung Galaxy Nexus. Android 4.0 was focused on simplifying and modernizing the overall Android experience around a new set of human interface guidelines. As part of these efforts, it introduced a new visual appearance codenamed "Holo", which was built around a cleaner, minimalist design, and a new default typeface named Roboto. It also introduced a number of other new features, including a refreshed home screen, near-field communication (NFC) support and the ability to "beam" content to another user using the technology, an updated web browser, a new contacts manager with social network ...
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Test (Unix)
test is a command-line utility found in Unix, Plan 9, and Unix-like operating systems that evaluates conditional expressions. test was turned into a shell builtin command in 1981 with UNIX System III and at the same time made available under the alternate name ''. Overview The test command in Unix evaluates the expression parameter. In most recent shell implementations, it is a shell builtin, even though the external version still exists. In the second form of the command, the [ ] (brackets) must be surrounded by blank spaces (this is because [ is a program and POSIX compatible shells require a space between the program name and its arguments). One must test explicitly for file names in the C shell. File-name substitution ( globbing) causes the shell script to exit. The test command is not to be confused with the reserved word that was introduced with ksh88. The latter is not a command but part of the ksh88 syntax and does not apply file-name substitution to glob expression ...
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Linux Distribution
A Linux distribution, often abbreviated as distro, is an operating system that includes the Linux kernel for its kernel functionality. Although the name does not imply product distribution per se, a distro—if distributed on its own—is often obtained via a website intended specifically for the purpose. Distros have been designed for a wide variety of systems ranging from personal computers (for example, Linux Mint) to servers (for example, Red Hat Enterprise Linux) and from embedded devices (for example, OpenWrt) to supercomputers (for example, Rocks Cluster Distribution). A distro typically includes many components in addition to the Linux kernel. Commonly, it includes a package manager, an init system (such as systemd, OpenRC, or runit), GNU tools and libraries, documentation, IP network configuration utilities, the getty TTY setup program, and many more. To provide a desktop experience (most commonly the Mesa userspace graphics drivers) a display server (the ...
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MINIX
MINIX is a Unix-like operating system based on a microkernel Software architecture, architecture, first released in 1987 and written by American-Dutch computer scientist Andrew S. Tanenbaum. It was designed as a clone of the Unix operating system and one that could run on affordable, Intel 8086-based home computers; MINIX was targeted for use in classrooms by computer science students at universities. Its name comes from ''mini-Unix''. MINIX was initially Source-available software, proprietary source-available, but was relicensed under the BSD licenses, BSD 3-Clause to become free and open-source software, free and open-source in 2000. MINIX was ported to various additional platforms in the 1990s, and version 2.0 was released in 1997 and was the first to be POSIX compliant. Starting with MINIX 3, released in 2005, the primary aim of development shifted from education to the creation of a high availability, highly reliable and Self-management (computer science), self-healing micro ...
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DragonFly BSD
DragonFly BSD is a free and open-source Unix-like operating system forked from FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and FreeBSD developer between 1994 and 2003, began working on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on 16 July 2003. Dillon started DragonFly in the belief that the techniques adopted for threading and symmetric multiprocessing in FreeBSD 5 would lead to poor performance and maintenance problems. He sought to correct these anticipated problems within the FreeBSD project. Due to conflicts with other FreeBSD developers over the implementation of his ideas, his ability to directly change the codebase was eventually revoked. Despite this, the DragonFly BSD and FreeBSD projects still work together, sharing bug fixes, driver updates, and other improvements. Dillon named the project after photographing a dragonfly in his yard, while he was still working on FreeBSD. Intended as the log ...
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FreeBSD
FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable home-class hardware, and has since continuously been the most commonly used BSD-derived operating system. FreeBSD maintains a complete system, delivering a kernel, device drivers, userland utilities, and documentation, as opposed to Linux only delivering a kernel and drivers, and relying on third-parties such as GNU for system software. The FreeBSD source code is generally released under a permissive BSD license, as opposed to the copyleft GPL used by Linux. The project includes a security team overseeing all software shipped in the base distribution. Third-party applications may be installed using the pkg package management system or from source via FreeBSD Ports. The project is supported and promoted by the FreeBSD Foundation ...
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