【Linux Operating System】——Linux Overview

Linux Operating System - Linux Overview

1. Operating systemOS

  Definition: An operating system ( Operating System, for short OS) is a computer program that manages computer hardware and software resources.

  Function: It is to encapsulate the operation of the hardware device in the computer system, which is called by the application software, and also to provide an operation interface for the user to interact with the system.

Among our common operating systems are:

PCend operating system

1、Windows

2、MacOS

3、Linux

mobile operating system

1. Android system and Apple system

2. The history of the operating system

Unix

  Before 1965, computers were not as common as they are now, they were not accessible to ordinary people, except in military or academic research institutions, and at the time mainframes could provide up to 30 terminals (30 keyboards, monitors) , connect a computer

In order to solve the problem of insufficient quantity

  After 1965, Bell Labs, MIT, and General Electric jointly launched a Multicsproject to make the mainframe support 300 terminals

  Around 1969, the project progressed slowly and funds were short, and Bell Labs withdrew from the research.

  When I quit this project in 1969, Ken Thompsonwhen I was bored in the laboratory, in order to run the "Interstellar Travel" parade on an idle computer, I spent a month around August while his wife was visiting relatives. Wrote a prototype of the Unix operating system

  In 1970, Bell Labs in the United States Ken Thompson, based on the BCPLlanguage , designed a very simple and very close to hardware B language (taking the initials of BCPL), and he wrote the first UNIXoperating system in B language.

  Because the cross-platform of the B language is poor, in order to be able to run this great Unix operating system on other computers, we are Dennis Ritchie和Ken Thompsongoing to study a better language based on the B language.

Ken Thompson (left) and Dennis Ritchie (right)

  In 1972, Bell Labs Dennis Ritchiein finally designed a new language based on the B language, and he took the BCPLsecond letter as the name of the language, which is the C language.

  In early 1973, the main body of the C language was completed. ThompsonAnd Ritchie can't wait to start completely rewriting the now-famous Unixoperating system with it.

  Early Unixsystems were developed for specialized hardware systems, and different manufacturers developed specialized Unix operating systems for their own servers.

​Minix

  Because AT&Tof (GE's) policy change, after Version 7 Unixlaunch, new terms of use were issued to privatize UNIX source code, and UNIX source code can no longer be used in universities.

  Andrew S. TanenbaumIn order to teach students the practical details of the operation of the operating system in the classroom, Professor (Tanenbaum) decided to AT&Tdevelop a compatible operating system without using any source code UNIXto avoid copyright disputes. He means small UNIX（mini-UNIX）and called it MINIX.

  ​Because it is only used for teaching, the function is not strong, so the bash used is used as a development environment, as a compilation tool, and the kernel is written , but at the beginning, Linux is not compatible with Unix, that is, applications running on Unix cannot run on Linux. That is, the interface between the application and the kernel is inconsistent, because Unix follows the POSIX specification, so Torvalds modified Linux, and followed , he standardized the interface specification between the application and the kernel); At first, Linux was only suitable for 386, and later after With the help of netizens all over the world, it can finally be compatible with a variety of hardware;Linux
MinixTorvaldsGNUgccLinux-v0.02POSIX（Portable Operating System Interface

  MinixThe most famous student user Linus Torvalds, he used the operating platform at the University of Helsinki in Finland to Minixbuild the kernel of a new operating system, which he called Linux.

LinuxThe kernel written as a hobby by Finn Linus Torvalds ( ) at the University of Helsinki.Linus Torvalds

  LinuxIt is a set of free-to - use and freely disseminated class Unixoperating systems.POSIXUNIXCPU

  Linux can run major UNIX utilities, applications and network protocols. It supports 32-bit and 64-bit hardware. Linux inherits the network-centric design idea of ​​Unix, and is a multi-user network operating system with stable performance.

  At present, the more well-known distributions on the market are: Ubuntu、RedHat、CentOS、Debain、Fedora、SuSE、OpenSUSE.

Unixwith Linuxdifference

  LinuxThe UNIXbiggest difference is that the former is free software with open source code, while the latter is traditional commercial software that implements intellectual property protection for source code.

  This should be their biggest difference. This difference is reflected in the fact that users have a high degree of autonomy for the former, but can only passively adapt to the latter; this difference also

  The development of the former is in a completely open environment, while the development of the latter is completely in a black box, and only the relevant developers can access the prototype of the product.

The specific differences are as follows:

• UNIXMost of the systems are matched with hardware, and Linuxcan run on a variety of hardware platforms.

• UNIXis commercial software, paid for, Linuxbut free software, free, open source .

• There are Linux commercialization RedHat Linux 、SuSe Linux、slakeware Linux, domestic red-flag, etc., as well as Turbo Linux.

• Unix mainly has Sun 的Solaris、IBM的AIX,　HP的HP-UX, as well as x86the platform's SCO Unix/Unixware.

3. Linux distribution

  The kernel ( kernel) is the heart of the system, the core program that runs programs and manages hardware devices such as disks and printers. It provides an abstraction layer between raw devices and applications.

The Linux kernel version is divided into a stable version and a development version. The two versions are related to each other and circulate each other:

• Stable: Industrial-strength, can be widely used and deployed. The new stable version only fixes some bugs or adds some new drivers relative to the older ones.
• Development Edition: Changes quickly due to experimenting with various solutions.

 Kernel source code URL: http://www.kernel.org All modifications to the Linux source code from all over the world will eventually be aggregated to this website, and the open source community led by Linus will screen and modify them and finally decide whether to enter the Linuxmainline kernel source code . middle.

  LinuxA distribution (also called a GNU/Linuxdistribution ) usually contains application software including desktop environments, office suites, media players, databases, and more.

ranking	Version	describe
1	MX Linux	Based on Debian and antiX
2	Linux Mint	Based on Ubuntu and Debian
3	Ubuntu	One of the top Linux distributions
4	Elementary OS	Based on Debian
5	Manjaro Linux	Based on Arch Linux
6	Zorin OS	Based on Debian
7	Fedora	Leading the way in software technology
8	Debian	designed to be very stable
9	CentOS	Best Linux for Enterprise Based on Fedora and Red Hat
10	Kali Linux	Based on Debian

LinuxWhat can be done?

  LinuxAvailable as an enterprise-class server, or an embedded development platform also includes a personal desktop system. Includes virtualization, database servers, Webservers, development platforms, and more.

Who should learn Linux?

  LinuxAdministrators, oracleadministrators, network engineers, program developers and more. The Linux system involves a wide range of aspects, and the ecology is getting stronger and stronger, which is very suitable for everyone to learn.

Personal desktop applications

  This field is linuxthe weakest link of traditional applications. Traditional linuxapplications have been suppressed by windows due to the shortcomings of simple interface, complex operation and few application software. However, in recent years, with the rise of excellent desktop environments such as ubuntu. fedoraWith the increase of its support, the share of linux in the field of personal desktop is gradually increasing.

Typical representatives: ubuntu, fedora,suse linux

​Server field

  linuxThe application in the server field is an important branch.

  linuxThe characteristics of free, stable, and efficient are well reflected here, but in the early days, they were also greatly restricted due to maintenance, operation and other reasons. However, in recent years, the Linux server market has been rapidly improved, especially in some high-end fields. particularly extensive

Typical representative:

• Red Hatcompany ASseries

• Fully open source debianseries

• suse EnterPrise 11series, etc.

​Embedded field

  In recent years linux, the application in the embedded field has been rapidly improved.

  linuxThe characteristics of stable operation, good support for the network, low cost, and software tailoring can be performed according to needs, and the minimum kernel can reach several hundreds KB, which has greatly improved its application in the embedded field in recent years.