Talking about Linux

Linux History
We all know that the development of PC can be said to be from the electron tube era to the transistor era, after the integrated circuit, and then to the VLSI, that is, the current PC, or from a minicomputer to a compatible machine to mainframe, the Linux operating system is the witness of this development. Linux operating system is a clone system of UNIX operating system. It was born on October 5 in 1991 (the first time it was officially announced). With the help of Internet networks and the concerted efforts of computer enthusiasts all over the world, it is now the most widely used UNIX class operating system in the world, and the number of users is growing rapidly. The birth, development and growth of the Linux operating system always relies on the following five pillars: the UNIX operating system, the MINIX operating system, the GNU program, the POSIX standard, and the Internet network.
The birth of the UNIX operating system
The Linux operating system is a cloned version of the UNIX operating system. The UNIX operating system is an American Bell lab.
Ken.thompson and Dennis Ritchie a time-sharing operating system developed on the DEC PDP-7 small computer in the summer of 1969. Ken Thompson developed a prototype of the UNIX operating system in one months in the summer of 1969, during his wife's return to his hometown of California, in order to run his favorite Space travel game on an unused PDP-7 computer. At that time, bcpl language (basic combinatorial programming language) was used, and after Dennis Ritchie was rewritten in 1972 with a very strong transplant C language, Unix systems were popularized in tertiary institutions.
MINIX Operating System
The MINIX system was developed by Andrew S. Tanenbaum (AST). AST is a University of Vrije in the Netherlands Amsterdam Mathematics and Computer science system work, is a senior member of ACM and IEEE (The world is also very few people are senior members of the two sessions), a total of more than 100 articles, 5 computer books. MINIX was compiled for 1987 years, mainly for students learning operating system principles, by 91 the version is 1.5. There are currently two versions in use: Version 1.5 and 2.0, when the operating system is free for use in universities, but other uses are not; Of course, it is now free and can be downloaded from many ftp. As an operating system, MINIX is not a good person, but it also provides system source code written in C and assembly language. This is the first time that aspiring programmers or hacker have been able to read the source code of the operating system, when the source code was carefully guarded by software vendors.
GNU Program
The GNU program and the Free Software Foundation (software FOUNDATION-FSF) were made by Richard M. Stallman
Founded in 1984. Designed to develop a complete operating system that is Unix-like and free software: the GNU system. (GNU is the "GNU's not Unix" recursive abbreviation, its pronunciation is "guh-new". A variety of GNU operating systems using Linux as the core are being used extensively. Although these systems are often referred to as "Linux," they should be called gnu/linux systems, strictly speaking. By the early 90, the GNU project had developed many high-quality free software, including the well-known Emacs editing system, the Bash shell program, the GCC series compiler, the GDB debugger, and so on. These software create a suitable environment for the development of Linux operating system, it is one of the foundation that Linux can be born. So far many people have called the Linux operating system "gnu/linux" operating system.
POSIX Standard
POSIX (Portable Operating System Interface for Computing Systems) is a cluster of standards developed by IEEE and ISO/IEC. The standard is based on existing UNIX practices and experiences, describing the operating system's invocation service interface, which is used to ensure that the compiled application can be ported on multiple operating systems at the source code level. It was made on the basis of early work of a UNIX user group (Usr/group) in the early 1980. The UNIX user group originally attempted to reconcile the differences between the call interfaces of the System V and Berkeley CSRG BSD systems, resulting in a/usr/group standard in 1984. In 1985, the IEEE Operating system Technical Committee Standard Subcommittee (TCOS-SS) began to oblige the IEEE Standards Committee, with the support of ANSI, to develop a formal standard for the operating system service interface for program source code portability. By the April 1986, the IEEE had developed a trial standard. The first formal standard was approved in September 1988 (IEEE 1003.1-1988), and is also a posix.1 standard that is often referred to later. The work of POSIX was transferred to the ISO/IEC community in 1989 and was continued to be established by the 15 working groups as standard. By 1990, POSIX.1 was formally approved for the IEEE 1003.1-1990 (also ANSI standard) and ISO/IEC 9945-1:1990 standards, in conjunction with the already adopted C language standards. POSIX.1 only specifies the system service Application Programming Interface (API), outlining only the basic system service standards, and therefore expects to set standards for other functions of the system. This is where the work of the IEEE POSIX begins to unfold. In 1990, there were 10 approved plans in progress, with nearly 300 people attending a quarterly meeting each week. The work started with Command and tool standards (POSIX.2), test method Standards (POSIX.3), real-time API (POSIX.4), etc. In the first half of 1990 years, 25 plans were in progress and 16 working groups were involved. At the same time, some organizations are also developing similar standards, such as X/OPEN,AT&T,OSF.
In the early 90, the POSIX standard was being finalized at the time of the final vote, which was 1991-1993. At this point, when Linux was just starting, this UNIX standard provided very important information for Linux, enabling Linux to be developed under standard guidance and compatible with most UNIX systems. In the original Linux kernel code (version 0.01, version 0.11) has been ready for the compatibility of Linux and POSIX standards.
Distribution of Linux
The composition of Linux: Hardware (CPU, calculator, controller, memory, IO device), kernel, library (System call two times package), application, terminal
Red Hat Linux
This is probably the most famous Linux version, and Red Hat Linux has created its own brand, and more and more people have heard of it. Red hat started business in 1994, employing more than 500 employees worldwide who are committed to open source code systems. Red Hat Linux is a good server in a public environment. It has its own company and can provide users with a complete set of services, which makes it particularly suitable for use in public networks. This version of Linux also uses the latest kernel and has the main package that most people need to use. The installation process for Red Hat Linux is simple and straightforward. Its graphical installation process provides easy setup of all information for the server. The disk partitioning process can be done automatically, and the GUI tools can be selected, even for Linux novices. The process of selecting a package is similar to other versions, and users can choose a package type or a special package. Once the system is up and running, users can get full technical support from the Web site and Red hat. I found Red hat to be an optimal version that meets the needs of the public. It works well in both the server and desktop systems. The only flaw with Red hat is that it has some nonstandard kernel patches, which makes it difficult to customize according to the needs of the user. Red Hat offers a wide range of technical support through forums and mailing lists, as well as its own company's telephone technical support, which is more appealing to group customers who require a higher level of technology support.
Centos
CentOS (Community ENTerprise Operating System) is one of the Linux distributions and is compiled from Red Hat ENTerprise Linux based on source code released under open source rules. Because of the same source code, some servers that require a high degree of stability are used with CentOS instead of the commercial version of Red Hat Enterprise Linux. The difference is that CentOS does not contain closed source software, and CentOS is an enterprise-class Linux distribution based on Red Hat Linux that provides free access to source code. Each version of CentOS receives a ten-year support (via security update). The new version of CentOS is released about once every two years, and each version of CentOS is updated periodically (approximately every six months) to support new hardware. This creates a secure, low-maintenance, stable, highly predictive, high-repeatability Linux environment. CentOS is an abbreviation for the Community Enterprise Operating system. CentOS is the product of the source code recompilation of Rhel (Red Hat Enterprise Linux), and it fixes a number of known bugs on the basis of Rhel, and is reliable with respect to other Linux distributions.
The philosophical thought of Linux
1, all documents: All the software, hardware equipment are stored in the form of files, performance, because the file mode of operation (open write read delect close) simple, so you can grind the differences between the hardware, improve the operation speed.
2, Linux is composed of a number of functions of a single program: The use of Shell programming small script, making development simple.
3. Minimize interaction with users
4. Use text files to save configuration information

Talking about Linux