Unix
Unix ( english [ ju ː nɪks ] ) is a multiuser operating system. It was developed by Bell Laboratories to support software development in August 1969. Today, Unix is generally for operating systems that either originated in the Unix system from AT & T (formerly Bell Laboratories) have or implement its concepts. Significant developer of Unix were Ken Thompson and Dennis Ritchie, the first, then wrote it in assembler language developed by Ritchie C programming language. With some Unix to date relevant concepts of information technology were first introduced, such as the hierarchical, tree-like structured file system folder structure. The early developers also defined a set of concepts and rules for software development, which became known as the Unix philosophy and to date have influence in computer science. Unix was developed further until the 1980s as open-source operating system designed primarily to U.S. Universities and had considerable influence on the hacker culture.
In the 1980s, it was commercialized by AT & T, which led to a number of independent developments and spin-offs and in the " Unix wars " so-called (Unix Wars ) resulted between different systems and manufacturers. The various Unix-based or derived operating systems today are taken together, the most popular operating systems for computers and for many types of electronic equipment containing a computer. The use of bandwidth of mobile devices such as smartphones extends beyond personal computers and Web servers to the largest supercomputers. Furthermore, in particular, the Unix-like Linux is also used as an embedded system in industrial measurement and control devices, in medical devices, consumer electronics and electronically controlled commodities such as household appliances, automobiles or wireless routers. Today's most widely used commercial, proprietary Unix variant is Mac OS X from Apple or its mobile version Apple iOS, the most popular open - source version is Linux and its cognate Android.
System functions and commands of Unix were originally to be called by a command line by the user via keyboard only input, the concept of the graphical user interface with windows and mouse operation was not known to the emergence time. Therefore, there is no standardized graphical Unix user interface, but a number of later-developed variants such as Gnome and KDE, of which many build on the X Window System. For many users such as professional programmers and system administrators the command line is still the preferred user interface. Unix derivatives for mobile devices such as smartphones and tablet computers, including Apple iOS and Android, use your own operating concepts. Network access to the command line and the file system is usually completely blocked.
- 6.1 prehistory
- 6.2 GNU 6.2.1 Linux
Typology of variants
Since UNIX is a registered trademark of the Open Group, only certified systems must bear the name UNIX. For the identification of "certified systems " Accordingly, one uses in the literature typically UNIX ( in caps or small caps ), while Unix is used as a term for unix -like systems.
Unix -like systems can be divided into Unix and Unix-like systems derivatives. The Unix derivatives include, for example, the BSD systems, HP- UX (Hewlett -Packard), DG / UX ( Data General ), AIX (IBM), IRIX ( Silicon Graphics ), UnixWare (SCO Group), Solaris (Oracle) and Mac OS X ( Apple). Other systems such as Linux or QNX, however, not based on the original Unix source code, but have been developed separately. They are called " Unix-like " refers to systems because they implement the typical Unix operating system functions ( POSIX) as a programming interface (API). A special case is BSD, which although originally was based on Bell Labs source code, but has been completely rewritten from a loose community of programmers since the mid- 1990s, so it is now free from the original, copyrighted code.
Dissemination
Originally distributed mainly at the university level, it was used from the 1980s and 1990s, especially in professional workstations and servers. With Linux, Mac OS X and as the basis of several popular operating systems for mobile devices, it reached from about the 2000s and the mass market for home users. The two most popular operating systems for smartphones and tablet computers, Apple iOS and Android, based BSD (iOS ) or Linux ( Android) on Unix-like operating systems. In September 2013 alone, over one billion Android devices were activated worldwide. For 2013, forecasted, the market research firm Gartner Group that more Android-based systems would be sold than PCs with Microsoft Windows for the first time. Also, Linux gained greater importance than open source operating system for enterprise applications and as an embedded system for electronic devices such as wireless routers or devices in consumer electronics.
Since the technology based on Unix, Linux can be very flexibly adapted and optimized, it has spread widely in data centers where specially adapted versions on mainframe computers, computer clusters ( see Beowulf ) or running supercomputers. In the TOP500 list of fastest computer systems (as of June 2012) a total of 462 operated exclusively on Linux systems and 11 partial ( CNK / SLES 9 ) are listed under Linux driven systems. Thus, 92.4 % and 94.6 % run completely at least partially under Linux. Almost all other systems are operated on a Unix or Unix-like systems. The largest in the desktop segment competitor Windows plays in the field of high performance computing systems with two ( 94th and 156), only a minor role ( 0.4%). In June 2011, there were four systems ( including number 40 ), which were operated under Windows.
Structure and Features
The Unix kernel has device driver alone access to the hardware and managed processes. In addition, he provides the filesystem available in modern versions in addition to network protocol stack. System calls from processes used to start ( system calls fork, exec ) and taxes of other processes as well as for communication with the file system. Accesses to the device drivers are mapped as hits on " special files " (device ) files in the file system. This will restore files and devices from the perspective of the processes and thus unifies the application programs as much as possible ( system calls open, read, write, etc ).
A variety of programs, including a C development system and a typesetting program ( troff ) complete the system.
The file system is organized as a hierarchical tree with any subdirectories, then a new concept that is understood everywhere today. Root directory ( root directory ) of this hierarchy is the "/" directory. One of the basic concepts of UNIX, is also floppy and CD drives, additional hard disk of your own computer or other computers, terminals, tape recorders and other special files in the file system mapping ( device files, files that appear to contain the data from one drive and reading " spend " ) rather than as some other operating systems ( inter alia, VMS, MS- DOS, Microsoft Windows) for separate directory hierarchies below the so-called " drive letter " to create. "Everything is a file " is a fundamental principle of Unix. This generalized concept file is in the nature of UNIX, and allows a simple, uniform interface for a variety of applications. In some UNIX systems processes and their properties even on mapped files ( proc File System).
The command interpreter, the shell - Unix is a normal process without privileges - as well as many standard commands allow the user to easily output redirection to files and pipes to communicate between processes.
A large collection of simple commands, the UNIX toolbox can be combined using the programming capabilities of the command interpreter and take complicated tasks. By simply combining the largely standardized tools is often avoided, that you have to write for " one-off tasks " or simpler administration work each specialized programs, as is often the case in other operating systems.
Among the important features of a typical Unix system include: high stability, multi-user, multi-tasking (now also multithreading ), memory protection and virtual memory ( first implemented in the BSD line), IP networking support ( also first in the BSD line), excellent scripting properties, a fully equipped Shell and a variety of tools ( the Unix commands ) and daemons. Operating systems of Unix and Unix workstations derivatives generally comprise a graphical user interface based on the X11.
Unix has historically been closely linked to the C programming language - both helped each other to break through, and so C is still the preferred language under Unix systems.
The name Unix
The system was originally developed by an employee of the name Unics, an acronym of Uniplexed Information and Computing Service and a pun on Multics. As will the shorter spelling of the decay tail "x " was created as a single letter, is unclear.
Whether the spelling Unix or UNIX instead is correct, has been debated for a long time. History is the spelling Unix, the elderly, the spelling of UNIX did not appear until later on - for purely aesthetic reasons. Today, they have different meanings in the literature are usually used as a term for Unix Unix -like systems, while UNIX uses to identify certified systems. When plural is in German " Unix " and that the third declension of Latin ajar " Unices " in use in English " Unixes " and also " Unices ".
History
Ken Thompson created in 1969 the first version of Unix in assembly language on the DEC PDP -7 as an alternative to Multics. As one of the first programs for the new kernel Thompson wrote with Dennis Ritchie the game Space Travel to explore the interfaces they need. 1972-1974, the operating system has been completely re-implemented in C and, together with a C compiler free of charge to various universities (AT & T was allowed as a state-controlled monopoly in the telecommunications industry sell no software ) - from a developed and at the University of California Berkeley BSD line of Unix. It was not until the late 1970s, AT & T finally tried himself, Unix to market profitably, resulting in the System V Unix line was born. In the 1980s, UNIX was the dominant operating system in the universities and there existed a wealth of various Unix derivatives, all descended in some form of the two main lines of BSD or System V. In response, the cry arose for standardization.
Standards
Each manufacturer changed and expanded the system in the 1980s, according to their own ideas. It developed versions with different capabilities, commands, command options, and libraries. Around 1985, initially, the IEEE began to standardize the interfaces for application programs. Hence the IEEE Standard 1003, which is called at the suggestion of Richard Stallman POSIX developed. It now consists of about fifteen documents with all aspects of Unix systems such as the command line interpreter (POSIX writes necessarily the Korn Shell ago) deal, the Unix commands and their options, the Ein-/Ausgabe and others.
The prices of the IEEE for the POSIX documentation are very high, the publication is prohibited by copyright law. More recently, therefore, a tendency to Single Unix Specification standard of the Open Group recorded. This standard is open, freely available on the Internet and accepts suggestions from everyone.
Trademarks
The rights to the brand Unix, so the use of the term, are at the Open Group.
Unix and Unix-like operating systems derivatives
Prehistory
Until Unix V7 appeared in 1979, the source code of UNIX was distributed against payment of the copying and disk cost at universities. Unix thus had the character of a free, portable operating system. The code has been used in lectures and publications and could be amended and supplemented according to their own ideas. The University of Berkeley has developed its own distribution with major extensions, the Berkeley Software Distribution (BSD ).
In the early 1980s, AT & T decided to commercialize Unix; AT & T source code could not be made publicly available at this time. Also the use in lectures etc. were excluded. High license fees collected - have been for BSD -based systems - as part of the code from AT & T came from.
Many companies licensed the UNIX source code and brought their own versions on the market, even Microsoft had with Xenix some time in a UNIX offer. Siemens adapted Xenix in 1984 to a German Unix called Sinix.
GNU
The unavailability of the source code led Richard Stallman to call 1983, the GNU project ( " GNU's Not Unix" ) to life. The aim of the project was to create a free Unix - compatible operating system. By 1990 the project had all the essential parts - including the GNU C compiler (gcc ) - developed, but with the exception of the kernel.
Linux
In 1987, the educational system Minix, developed by Andrew S. Tanenbaum at the Free University of Amsterdam. Minix was a Unix clone with microkernel, C compiler, text editor and many commands that ran on weak PC hardware as relatively undemanding system. The source code was part of the deal. While it was commercially and proprietary, but had a very low price. As previously served Unix, this system many as a starting point for your own experiments.
In 1991, the student Linus Torvalds was working on a terminal emulator, with which he attempted to access a university computers. Over time, he built a file system access and many other useful features. Soon he realized that he programmed more than a terminal emulator. The source text he published in the newsgroup comp.os.minix as a kernel, which should be run on an Intel 386 PC. First, his project Freax be called. As the administrator of the University awarded him as the login for his FTP repository "Linux", he named the project after this. In the source code of version 0.01 of Linux nor the name Freax occurs ( " Makefile for the kernel FREAX ").
Free BSD derivatives
In 1992, with 386BSD by Bill and Lynne Jolitz another free system for 80386 processors. It consisted of a patch for the derived not from AT & T free parts of the BSD distribution, and formed another free, very advanced operating system for Intel processors.
Published in 1994, Berkeley 4.4BSDLite the latest version of their distribution, the AT & T source code was liberated. This made together with 386BSD the basis for NetBSD, FreeBSD and OpenBSD shortly thereafter.
Mac OS X
Mac OS X is a 2001 imagined Apple's successor to the NeXTStep system. The base is a hybrid called XNU kernel, which consists of a Mach microkernel and parts of the FreeBSD kernel. The base system called Darwin also includes derived from BSD programs that are expected in a Unix-like environment. The development of Darwin was placed under the Open Source License Apple Public Source License, which was recognized in version 2.0 as a free software license by the Free Software Foundation. Together with published under proprietary licenses system parts such as the work environment Aqua forms Darwin Mac OS X. Since version 10.5 Leopard Mac OS X is certified as a true Unix system from the Open Group.
OpenSolaris
Since 2005, Solaris ( version 10 ) is available for royalty-free use in the current version. Solaris runs on 32 -bit and 64 -bit processors ( x86/AMD64, EM64T) AMD and Intel, as well as on 64- bit systems with Sun's UltraSPARC. For access to sources and staff, including an expansion, it is available in the version of OpenSolaris, the functionally no different from the binary version.
Release dates
The following summary gives only a general overview. There are only mentioned the most important systems. These have their own versions and their own history of development, respectively.