Linux is a free and open source UNIX-like operating systems. The operating system kernel created by Linus Torvalds for the first time in October 5, 1991, after adding an application to become the Linux operating system. Linux is free software and open source software development in the most famous example. As long as the GNU General Public License (GPL), any individuals and institutions are free to use all the underlying source code for Linux is also free to modify and redistribute. It simply is an open source UNIX-like operating system.
Multics project
Why is it like? It had to start with UNIX, UNIX is the operating system, so it is to do everything from Multics project, an early computer architectures is difficult to use in addition to the cup processing speed as well as user interface is difficult to use, because At that time only reader input devices, output devices only printer, the user can not interact with the operating system. Wrong place procedures to debug must be re-clocking, particularly troublesome and very few users many machines, in order to solve this situation presented MIT Compatible Time-Sharing System Compatible Time-Sharing System CTSS abbreviated as in 1961, this operating system allows multiple users to connect to a mainframe computer through a terminal software, while many people use computer resources for computing, everything seems to have got better, with the development of Multics project CTSS why should it, in fact, most of the CTSS operating system You can only drive 30 to a terminal, in order to allow more people to use computer resources operations, involved in the development of this project in 1964 at Bell labs, MIT and General Electric Company with the United States, aimed at connecting the 1000 terminal, support 300 users simultaneously on-line that is Multics CTSS is an upgraded version, but the joint development progress is not guaranteed, Bell labs withdrew from the joint development, MIT and General electric continue to develop Multics project.
UNIX was born
Bell Labs quit after a man named Ken Thompson programmers This guy is a genius who invented language B (? Formerly the C language) is also a creative person and the C language in Bell Labs Nine projects are in the main developers, 2006 google and join with colleagues involved in the design of the language go together. The Thompson is a fun loving person in the development of Multics project himself developed a game called Space Travel Multics project after exiting Bell Thompson to be able to continue playing the game, Thompson had to find an old PDP-7 machine, rewrote his "Space Travel" game, in the game after transplantation good, Thompson started his own tools and expanded into a complete operating system. Thompson called his colleagues together to open the black, colleagues of his game is not cold, but he's very interested in the operating system, so Thompson and Dennis Ritchie (C language inventor) led this other colleagues completed the file system, process, device files, command line interpreter and some small utility programs, the time has come to 1970, the project team put this system is called UNIC (Uniplexed Information and Computing system) , early UNIC very simple in that old-fashioned PDP -7 machine can only support two users, because of poor performance PDP-7, Ken Thompson and Dennis Ritchie decided to migrate to the first edition of UNIX machines PDP-11/20, the development of the second edition UNIX. After the performance, can really provide for concurrent use, when a colleague Brian Kelin Han asked to name the UNIX operating system to replace the previous UNIC, some applications of the first edition of the UNIC written entirely in assembly language B is a mixture of languages, called an interpreted language and written in assembly language, during system programming is not strong enough, so Thompson and Ritchie its transformation, and in 1971 co-inventor of the C language, soup 1973 P Johnson and Ritchie C language rewritten Unix, Third Edition formation UNIX.
UNIX development
Because Bell Labs is under the US AT & T's, and was not supported UNIX attitude is not exclusive, in order to allow better development at this time and UNIX Berkeley academics involved in, since the third version of UNIX is C language development, portability aspect much better than the compilation, Bill Joy at Berkeley UNIX source code to proceed after getting the version modified to suit their own computers, while increasing the corresponding application and named Berkeley Software Distribution (BSD) this is very important points for UNIX, FreeBSD after that evolved from this, this Bill Joy also rely on BSD founder of the famous SUN company. At that time, the good portability combined with the absence of copyright disputes number of commercial companies are beginning to study UNIX and AT & T's own System V, IBM's AIX and HP and DEC and other companies, has launched its own host with its own Unix operating system.
UNIX copyright disputes
In 1975, UNIX 4,5,6 released three versions. In 1978, there have been about 600 machines running UNIX. In 1979, version 7 release, this is the last extensive research released versions of UNIX. But AT & T's commercial considerations in, trying to recover the UNIX copyrights, it is specifically mentioned in the release, the student may not provide the source code, a move that caused a lot of commercial disputes. UNIX System V Release 4 was released shortly after, AT & T will sell all of its rights to the UNIX Novell. Novell desirable in order to counter Microsoft's Windows NT, but its core market has been seriously hurt, in 1993 Novell will sell the trademark rights of SVR4 to the X / OPEN Company, which became the definition of UNIX standards bodies. In 1996, X / OPEN and OSF / 1 merger, creating Open Group, which it announced the "Single UNIX Specification" defines the operating system has what features can crown on UNIX name, relatively, does not meet these criteria However, the Unix operating system similar properties can be called "class Unix" (unix-like). This is linux is known as the main reason for UNIX-like operating systems, but linux is so used to it?
Linux was born
Because AT & T's System V release harsh terms of the operating system (for students not provide the source code), then a man named Tanenbaum teacher anxious, do not provide the source code programs will continue to how to do it, but under our only developing a system called Mini UNIX referred minix, the development process does not use any code of aT & T, on licensing, copyright Minix announcement in early is considered to be relatively free: Professor Tanenbaum take Minix as hope a public textbooks and publishers want to protect the balance of copyright under the code, it only requires a very low license fee (buy a disc you can get the source code). But because it is not a licensing program open source, which makes the young age of Linus Torvalds unhappy, the initiation of an operating system to write their own idea of how difficult it is to write a single scratch, bought after the start minix a large number of study design minix, and to design their own kernel Linus 'Minix meaning Linus' Minix kernel, the kernel and minix kernel completely different kernel and the original Unix are used monolithic, and minix uses a micro-kernel, learn copyright issues in front of Linus Torvalds decided to change his original agreement (this agreement will limit the commercial use) to GNU GPL agreement to replace the original Linus Torvalds said the name of the kernel is "Freax" meaning free ( "free") and singular ( "freak") in conjunction with the word, and attach the "X" that commonly used letters, in September 1991 by the University of FTP administrator Ari Lemmke posted on the Internet, administrators dislike this Freax not sound, named Linux, at this time? Linux was born