Knowledge content:
1. Introduction to the operating system
2. Introduction to the Linux operating system
3. Linux installation
4. Introduction to common Linux commands
1. Introduction to the operating system
1. Why do you need an operating system
A modern computer system consists of a processor, main memory, hard disk, keyboard, mouse, monitor and other input and output devices. Generally speaking, a modern computer system is a complex system.
Programmers cannot understand all the details of hardware operations. It is very tedious work to manage these hardware and optimize their use. This tedious work is done by the operating system. With him, programmers can benefit from these tedious work. When you are freed, you only need to consider the writing of your own application software. The application software directly uses the functions provided by the operating system to indirectly use the hardware.
2. What is an operating system
An operating system is a control program that coordinates, manages and controls computer hardware and software resources
The operating system is located between the computer hardware and the application software, and is essentially a software. The operating system consists of two parts: the kernel of the operating system (running in kernel mode, managing hardware resources) and system calls (running in user mode, providing a system call interface for applications written by application programmers). Therefore, simply speaking of the operating system is running in kernel mode, which is inaccurate
3. The role of the operating system
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Processing management
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Memory management
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File system
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Networking
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Security mechanism (Security)
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User interface
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Driver (Device drivers)
4. Introduction to commonly used operating systems
(1) DOS
DOS is the abbreviation of Disk Operation System in English, and disk operating system in Chinese. It has been upgraded to version 6.22 since the launch of version 1.0 in 1981. The interface of DOS is operated by character commands and can only run a single task.
(2)Windows
Windows adopts a graphical mode GUI, which is more user-friendly than the way DOS needs to type commands. With the continuous upgrade of computer hardware and software, Microsoft's Windows is also constantly upgraded
(3)UNIX
The UNIX operating system was designed from a minicomputer, and from the very beginning it was a multi-user, multi-task general operating system, which provided users with an interactive and flexible operation interface, supported data sharing among users, and provided many The integrated tools to improve the user's work efficiency, while being able to port to different hardware platforms. The reliability and stability of UNIX operating system are unmatched by other systems, and it is recognized as the best Internet server operating system. In a sense, almost the entire backbone of the Internet is built on the numerous machines and network devices running UNIX.
Famous Unix systems: FreeBSD, UNIXSUN, UNIX (SOLARIS), IBM UNIX
(4)Linux
To be precise, Linux should be an operating system that conforms to the UNIX specification, and Linux is developed based on source code. Linux is a free-to-use and freely disseminated UNIX-like operating system designed and implemented by thousands of programmers around the world. Users can obtain it and its source code without paying any fees, and can make necessary modifications to it according to their needs, use it free of charge, and continue to disseminate it without restriction.
Linux is known for its efficiency and flexibility. It can realize all the UNIX features on the PC computer, and has the ability of multi-tasking and multi-user. It also includes application software such as text editors and high-level language compilers. It also includes an X-Windows graphical user interface with multiple window managers, allowing us to operate the system using windows, icons, and menus as we did with Windows NT. It is a powerful, high-performance, stable and reliable operating system.
Famous Linux systems: Ubuntu, Fedora, Debian, RedhatEnterpriseLinux, centos
(5) Other operating systems
Mac OS is a dedicated operating system for Apple's Macintosh machines. Essentially, Mac OS is also a variant of UNIX.
2. Introduction to Linux Operating System
1 Overview
The Linux operating system was born on October 5, 1991. Linus Torvalds created the Linux operating system at the University of Helsinki, Finland. Its appearance broke the dominance of the Windows operating system.
Linux is a set of Unix-like operating systems that are free to use and spread freely. It is a multi-user, multi-tasking, multi-threading and multi-CPU operating system based on POSIX and UNIX. It can run major UNIX tools, 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.
Strictly speaking, the word Linux itself only means the Linux kernel, but in fact, people are used to using Linux to describe the entire operating system based on the Linux kernel and using various tools and databases of the GNU Project.
2. Main Features
- Multitasking, multiuser, multiplatform, multiprocessor
- Protect memory used by applications
- "On-demand disk retrieval": When any executable file is executed, only those code segments that are actually used will be read into memory by the system, which saves a lot of time and speeds up execution.
- Shared memory pages, applications and hard disk cache use a unified memory pool.
- With dynamic link library (Dynamic Linked Library DLL) and static link library
- Can do memory field preservation (Core Dumps) for later analysis.
- All original program source code is available, including the entire core and all driver development tools and all applications
- Supports several common file systems
- Powerful network function
3. Linux installation
1. Installation Preface
I use the virtual machine to install the Linux operating system, the virtual machine uses the oracle's VM virtualbox, and the downloaded operating system image is the Linux centos6.9
Related information download address:
Virtual machine download: https://www.virtualbox.org/
centos6.9: http://isoredirect.centos.org/centos/6/isos/x86_64/
2. Preparations before installing the system
(1) Download and install the virtual machine
(2) Download the operating system image file (iso)
For the above two steps, you can download the corresponding installation package and image file from the link in (1)
3. Start the installation