Only by understanding the past can we know it: Unix legends

The title of the article: understanding the past before you can know it: Unix legends. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

Only by understanding the past can we know and understand it. In conclusion, we will know how to plan and how to proceed tomorrow. In the scroll wheel of time, many things are just like a meteor, and some things are able to withstand the test of time, which is a constant charm and relishing, so far. You need to know how to choose tomorrow and how to do it. Instead of blindly following all kinds of cutting-edge technologies today, you must carefully understand and review history.

Unix is the old operating system that is still alive. It has been around for nearly 40 years. In today's rapidly updated computer world, Unix has always maintained its holy aura, its twists and turns, its sighing history, and the ideological changes it has triggered, the profound impact on today's computer culture, the people and things that have taken place in the last 40 years, have turned it into a legend that cannot be left alone.

This is a history that all people in the computer industry, especially software developers, need to understand. The legendary history of Unix is the most representative of the whole computer world culture. It has the greatest and most profound influence on the whole computer world culture. His experience in the past has brought us a new trend of thought in the computer world.

Only by understanding the history of this period can we understand the right, the right, and the right, the right, and the right. Hope that this article will allow you to feel the powerful pulse of the computer world, so that you can embark on this exciting road.

The following is an outline of this article:

Part 1
Unix Origin
Unix splitting
Unix legal disputes
GNU open-source organization
Linux was born
Linux leader today

Next
Unix and hacker culture
Unix lessons
Unix family Spectrum
Unix features
Unix influence and Philosophy
Unix hate manual

Unix Origin

Looking back at the history of Unix, we need to talk about a project called Multiplexed Information and Computing Service. In the 1960s s, most computers used Batch Processing (that is, when a job accumulates a certain number of jobs ). At that time, our well-known American Telephone and Telegraph Inc .; AT&T, General Electric Appliance Company (General Electric ICS; G. E .) and mas usetts Institute of Technology (MIT) are planning to develop a General-Purpose, Time-Sharing, and Multi-User operating system, this MULTICS was designed to run on a large GE-645 host. However, this project is too complex, the overall goal is too large, it combines too many features, the progress is too slow, there has been no results in a few years, and the performance is very low. So in February 1969, Bell Labs decided to withdraw from the project.

Anyone familiar with this history knows that there is a Ken Thompson in Bell's lab who writes a game called Space Travel for the MULTICS operating system, after running on MULTICS, he found that the game was slow and expensive-$75 for each operation. After exiting the project. To make the game play, he found Dennis Ritchie to develop an extremely simple operating system for the game. This is the later Unix. (It is worth mentioning that at that time they wanted to write in DEC-10, and later did not apply, I had to find a abandoned Digital PDP-7 mini computer at the corner of the lab to make their plan, and the computer didn't even have an operating system, so they developed an operating system prototype in just a month using the assembly language.) their colleague Brian Kernighan liked the system very much and laughed at Ken Thompson: "The system you wrote is really bad. It's just called Unics." The name of Unics is a nickname relative to MULTICS. The post industry is changed to Unix. As a result, Unix was created by games and jokes. It was in August 1969. This year, Linus Torvalds, the father of Linux, was born in Finland.

In 1971, Ken Thompson wrote a sufficiently long application report and applied for a PDP-11/24 machine. So the first version of Unix came out. Finished on a PDP-11/24 machine. This computer only has 24 KB of physical memory and KB of disk space. Unix occupies 12 kb of memory, and the remaining half of memory can support Space Travel games for dual-purpose users. The well-known fork () System Call emerged at this moment.

In 1973, Ken Thompson and Dennis Ritchie felt that it was too headache to transplant in assembly language. They wanted to complete the third edition in advanced language, the idea of developing programs completely using assembly languages was crazy. At first they tried to use Fortran, but they failed. Later, they developed it in a Language called BCPL (Basic Combined Programming Language). They integrated BCPL to form the B Language. Later, Dennis Ritchie thought that the B Language still could not meet the requirements, that is, the Language B is improved. This is the famous C language today. Therefore, Ken Thompson and Dennis Ritchie successfully used the C language to rewrite the third-edition Unix kernel. So far, the Unix operating system is quite convenient to modify and transplant, laying a solid foundation for the popularization of Unix in the future. While the perfect combination of Unix and C becomes a unity, C and Unix soon become the world's dominant.

The first Unix article "The UNIX Time Sharing System" consists of Ken Thompson and Dennis

Ritchie was published on the Communications of the ACM in July 1974. This is the first time UNIX has been exposed to the outside world. As a result, it has aroused widespread interest in the academic community and obtained the source code. Therefore, the fifth version of Unix provides the Protocol "for educational purposes only" to various universities for teaching, became an example textbook in the operating system course at that time. Various University companies began to improve and expand Unix through the Unix source code. As a result, Unix is widely used.

 

Ken Thompson & Dennis Ritchie,

Unix splitting

In 1978, it was a revolutionary year for Unix, because the academic leader UC Berkeley launched a sixth version, added some improvements and new features into Unix. This is the famous "1 BSD (1st Berkeley Software Distribution)", which created another branch of Unix: BSD series. In the same period, AT&T established the USG (Unix Support Group) to convert Unix into commercial products. Since then, BSD Unix and AT&T's Unix stand-alone courtesy. Unix is divided into the System IV and 4.x BSD mainstream, each of which is booming.

The seventh version of Unix, published in 1979, is called "the last real Unix". The Unix kernel of this version is only 40 K bytes. Later, this version was transplanted to the VAX machine (I used this VAX machine when I was studying C language in College). I still remember that my biggest hobby on the VAX machine was to use the talk command to chat with others, haha ). Versions 8, 9, and 10 released in 1980s are only authorized to a few universities.

In 1982, AT&T developed the first version of UNIX System III based on version 7, a commercial version for sale only. To solve the chaotic UNIX version, AT&T integrated various UNIX developed by other universities and companies and developed UNIX System V Release 1. This new commercial release of UNIX does not contain source code. Therefore, the University of California Berkeley continues to develop bsd unix as an alternative to UNIX System III and V. One of the most important contributions of BSD to UNIX is TCP/IP. BSD has eight major releases including TCP/IP: 4.1c, 4.2, 4.3, 4.3-Tahoe, 4.3-Reno, Net2, 4.4, and 4.4-lite. The TCP/IP code in these releases is almost the predecessor of TCP/IP implementation in all systems, including the source code of BSD for both AT&T System v unix and Microsoft Windows.

At the same time, some other companies have begun to provide commercial UNIX systems for their minicomputers or workstations, some choose System V as the basic version, and some choose BSD. Bill Joy, a major developer of BSD, developed SunOS Based on BSD and finally founded Sun Microsystems.

In 1991, a group of BSD developers (Donn Seeley, Mike Karels, Bill Jolitz, and Trent Hein) left the University of California and founded Berkeley Software Design, Inc (BSDI ). BSDI is the first vendor to provide full-featured commercial bsd unix on cheap and common Intel platforms. Later, Bill Jolitz left BSDI and started the ipvbsd job. Javasbsd is considered FreeBSD, OpenBSD and NetBSD, DragonFlyBSD.

This is a Unix era in which AT&T wants to privatize itself. To privatize Unix, in 1986 IEEE appointed a commission to develop a standard for one open Operating system, known as POSIX (Portable Operating Systems Interface ). Add X to the end. I don't know whether it is for good or because it is essentially a UNIX standard. Of course, AT&T Unix won the standard-setting war and the registered trademark Unix. At this time, the advocates of BSD are the opposite of the cold and heartless corporate empire. In terms of sales volume, AT&T UNIX never keeps up with BSD/Sun. By 1990, AT&T and BSD had been difficult to distinguish, because each of them had their own new inventions.

During this period, Unix shared by the world from the laboratory was in a critical period of privatization.

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