In some versions of the Unixoperating system, the term universe was used to denote some variant of the working environment. During the late 1980s, most commercial Unix variants were derived from either System V or BSD. Most versions provided both BSD and System V universes and allowed the user to switch between them. Each universe, typically implemented by separate directory trees or separate filesystems, usually included different versions of commands, libraries, man pages, and header files. While such a facility offered the ability to develop applications portable across both System V and BSD variants, the requirements in disk space and maintenance (separate configuration files, twice the work in patching systems) gave them a problematic reputation. Systems that offered this facility included Harris/Concurrent's CX/UX, Convex's Convex/OS, Apollo's Domain/OS (version 10 only), Pyramid's DC/OSx (dropped in SVR4-based version 2), Concurrent's Masscomp/RTU, MIPS Computer Systems' RISC/os, Sequent's DYNIX/ptx and Siemens' SINIX.
Some versions of System V Release 4 retain a system similar to Dual Universe concept, with BSD commands (which behave differently from classic System V commands) in /usr/ucb, BSD header files in /usr/ucbinclude and library files in /usr/ucblib. /usr/ucb can also be found in NeXTSTEP and OPENSTEP, as well as Solaris.
In computing, the Executable and Linkable Format, is a common standard file format for executable files, object code, shared libraries, and core dumps. First published in the specification for the application binary interface (ABI) of the Unix operating system version named System V Release 4 (SVR4), and later in the Tool Interface Standard, it was quickly accepted among different vendors of Unix systems. In 1999, it was chosen as the standard binary file format for Unix and Unix-like systems on x86 processors by the 86open project.
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.
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 JTC 1 SC22 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.
Xenix is a discontinued version of the Unix operating system for various microcomputer platforms, licensed by Microsoft from AT&T Corporation in the late 1970s. The Santa Cruz Operation (SCO) later acquired exclusive rights to the software, and eventually replaced it with SCO UNIX.
A man page is a form of software documentation usually found on a Unix or Unix-like operating system. Topics covered include computer programs, formal standards and conventions, and even abstract concepts. A user may invoke a man page by issuing the man command.
The cd command, also known as chdir, is a command-line shell command used to change the current working directory in various operating systems. It can be used in shell scripts and batch files.
In computing, a symbolic link is a file whose purpose is to point to a file or directory by specifying a path thereto.
GoboLinux is an open source operating system whose most prominent feature is a reorganization of the traditional Linux file system. Rather than following the Filesystem Hierarchy Standard like most Unix-like systems, each program in a GoboLinux system has its own subdirectory tree, where all of its files may be found. Thus, a program "Foo" has all of its specific files and libraries in /Programs/Foo, under the corresponding version of this program at hand. For example, the commonly known GCC compiler suite version 8.1.0, would reside under the directory /Programs/GCC/8.1.0.
The Filesystem Hierarchy Standard (FHS) is a reference describing the conventions used for the layout of a UNIX system. It has been made popular by its use in Linux distributions, but it is used by other UNIX variants as well. It is maintained by the Linux Foundation. The latest version is 3.0, released on 3 June 2015.
The archiver, also known simply as ar, is a Unix utility that maintains groups of files as a single archive file. Today, ar is generally used only to create and update static library files that the link editor or linker uses and for generating .deb packages for the Debian family; it can be used to create archives for any purpose, but has been largely replaced by tar for purposes other than static libraries. An implementation of ar is included as one of the GNU Binutils.
Unix System V is one of the first commercial versions of the Unix operating system. It was originally developed by AT&T and first released in 1983. Four major versions of System V were released, numbered 1, 2, 3, and 4. System V Release 4 (SVR4) was commercially the most successful version, being the result of an effort, marketed as Unix System Unification, which solicited the collaboration of the major Unix vendors. It was the source of several common commercial Unix features. System V is sometimes abbreviated to SysV.
These tables provide a comparison of operating systems, of computer devices, as listing general and technical information for a number of widely used and currently available PC or handheld operating systems. The article "Usage share of operating systems" provides a broader, and more general, comparison of operating systems that includes servers, mainframes and supercomputers.
The file command is a standard program of Unix and Unix-like operating systems for recognizing the type of data contained in a computer file.
SINIX is a discontinued variant of the Unix operating system from Siemens Nixdorf Informationssysteme. SINIX supersedes SIRM OS and Pyramid Technology's DC/OSx. Following X/Open's acceptance that its requirements for the use of the UNIX trademark were met, version 5.44 and subsequent releases were published as Reliant UNIX by Fujitsu Siemens Computers.
In computing, a shebang is the character sequence consisting of the characters number sign and exclamation mark at the beginning of a script. It is also called sharp-exclamation, sha-bang, hashbang, pound-bang, or hash-pling.
The Berkeley Software Distribution or Berkeley Standard Distribution (BSD) is a discontinued operating system based on Research Unix, developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley. The term "BSD" commonly refers to its descendants, including FreeBSD, OpenBSD, NetBSD, and DragonFly BSD.
Unix is a family of multitasking, multiuser 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.
In the C and C++ programming languages, unistd.h is the name of the header file that provides access to the POSIX operating system API. It is defined by the POSIX.1 standard, the base of the Single Unix Specification, and should therefore be available in any POSIX-compliant operating system and compiler. For instance, this includes Unix and Unix-like operating systems, such as GNU variants, distributions of Linux and BSD, and macOS, and compilers such as GCC and LLVM.
The History of the Berkeley Software Distribution begins in the 1970s.
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