Basic Linux Knowledge

I. INTRODUCTION of Linux

Linux is a free and open source Unix-like operating system. is currently the most widely used, most people operating system. The kernel of the operating system was first released by Linus Torvalds on October 5, 1991. After adding the user-space application, it becomes a Linux system. Linux is the most famous example of the development of free software and open source software. Any individual or institution is free to use all the underlying source code of Linux and can be freely modified and republished as long as the general Public License of the gun is followed. Most Linux systems also include programs such as the X window that provides the GUI.

Linux is strictly a single-finger kernel of the operating system, as the operating system contains many user graphics interfaces and other useful tools. Linux is now commonly used to refer to a complete Linux-based operating system, and the kernel is called the Linux kernel. Since these user-space-enabled system tools and libraries are primarily provided by the GNU program, which Richard Stallman launched in 1983, the Free Software Foundation proposes to name the combination gnu/linux.

Linux was originally a free operating system under the PC that supported the Intel x86 architecture. Currently, Linux has been ported to more computer hardware platforms, much more than any other operating system. Linux is also widely used in embedded systems, such as mobile phones, tablets, routers, televisions, and video games. The Android operating system, which is widely used on mobile devices, is created on top of the Linux kernel.

Typically, Linux is packaged as a Linux distribution for personal computers and servers, and some popular mainstream Linux distributions, such as Debian (and its derived versions of Ubuntu, Linux Mint), Fedora (and its associated version red Hat Enterprise Linux, CentOS), and openSUSE. Linux distributions include the Linux kernel and the support kernel utilities and libraries, often with a large number of applications to meet a variety of needs. Linux distributions used by personal computers typically contain X window and a corresponding desktop environment, such as GNOME or KDE. Desktop Linux operating system commonly used applications, including Firefox browser, libreoffice Office software, GIMP image processing tools and so on.

Ii. A brief history of Linux

The birth, development and growth of the Linux operating system always relies on five important pillars: the UNIX operating system, the MINIX operating system, the GNU program, the POSIX standard, and the Internet network.

1981 IBM introduced microcomputer IBM PC.

1991, the GNU program has developed a number of tool software, the most anticipated GNU C compiler has emerged, the GNU operating system Core Hurd has been in the experimental phase, there is no availability, virtually no development of the full GNU operating system, But GNU lays out the Linux user base and development environment.

In early 1991, Linus Torvalds began learning Minix operating systems on a 386SX compatible microcomputer. In April 1991, Linus Torvalds began brewing and starting its own operating system.

April 13, 1991 released on Comp.os.minix said that he has successfully transplanted bash to the Minix, and has been put down, can not leave the shell software.

July 3, 1991, the first Linux-related message was published on the Comp.os.minix (of course, there is no Linux this name, at that time Linus Torvalds's mind may be freax,freax English meaning is grotesque, monsters, whimsical, etc.).

On the October 5 of 1991, Linus Torvalds released a message on the Comp.os.minix News Group, formally announcing the birth of the Linux kernel (freeminix-like kernel sources for 386-at).

In 1993, about 100 programmers took part in the coding/modification of the Linux kernel, where the core group consisted of 5 people, at which time the code for Linux 0.99 was about 100,000 lines and the user was around 100,000.

In March 1994, Linux1.0 released a code volume of 170,000 lines, which was released under a completely free and free agreement, followed by a formal GPL agreement.

In January 1995, Bob Young founded Redhat (Little Red Riding Hood), with Gnu/linux as the core, with more than 400 open-source program modules, developed a brand-name Linux, the Redhat Linux, called Linux "Distribution", Sold on the market. This is an innovation in the business model.

In June 1996, the Linux 2.0 kernel was released with approximately 400,000 lines of code and could support multiple processors. At this time, Linux has entered the practical stage, around the world about 3.5 million people use.

In February 1998, a group of young "old wildebeest cadres" led by Eric Raymond finally realized the essence of the industrialization road of gnu/linux system, not what philosophy of freedom, but the driving of market competition, founded "Open Source intiative" (Open Source Association) "Revival" banner, in the Internet World launched a historic Linux industrialization movement.

Linux 2.4 was released in January 2001 to further enhance the scalability of the SMP system, and it also integrates many features to support Desktop systems: USB,PC Card (PCMCIA) support, plug-and-play, and more.

December 2003, Linux version 2.6 kernel release, compared to the 2.4 version of kernel 2.6 in the support of the system has changed greatly.

In the 1th month of 2004, SuSE was married to Novell,sco, who continued to force "alms" around the stigma, Asianux, MandrakeSoft also announced quarterly profits for the first time in five years. In March, SGI announced the successful implementation of the Linux operating system supporting 256 Itanium 2 processors.

Three, the main characteristics

Basic ideas

The basic idea of Linux has two points: first, everything is a document; second, each software has a definite purpose. The first article in detail is that everything in the system boils down to a file, including commands, hardware and software devices, operating systems, processes, and so on for the operating system kernel, all of which are considered to have their own attributes or types of files. Linux is Unix-based, largely because of the similarity between the two basic ideas.

Completely free

Linux is a free operating system that can be obtained free of charge through the Internet or other channels, and can be arbitrarily modified by the source code. This is not what other operating systems can do. Because of this, countless programmers from all over the world are involved in the modification and writing of Linux, and programmers can change them according to their own interests and inspirations, which allows Linux to absorb the essence of countless programmers and grow.

Fully compatible with the POSIX1.0 standard

This makes it possible to run common DOS and Windows programs under Linux with the appropriate simulator. This lays the groundwork for users to go from Windows to Linux. When many users consider using Linux, they think about whether the programs that were common to windows before are working properly, which eliminates their doubts.

Multi-user, multi-tasking

Linux supports multiple users, each user has their own special rights to the file device, to ensure that the user does not affect each other. Multitasking is one of the most important features of computers now, and Linux allows multiple programs to run simultaneously and independently.

A good interface

Linux has both a character interface and a graphical interface. In the character interface, the user can use the keyboard to enter the appropriate instructions. It also provides a x-window system similar to the Windows graphical interface that allows users to manipulate it using the mouse. In the X-window environment, like in Windows, it can be said to be a Linux version of Windows.

Supports multiple platforms

Linux can run on a variety of hardware platforms, such as those with x86, 680x0, SPARC, and Alpha processors. In addition, Linux is an embedded operating system that can run on a handheld, set-top box, or game console. The Linux version 2.4 kernel, released in January 2001, has been able to fully support Intel's 64-bit chip architectures. Linux also supports multi-processor technology. Multiple processors work at the same time, which greatly improves system performance.

Basic Linux Knowledge