Linux is a complete multitasking, multi-user operating system (just like other versions of UNIX). Linux is quite compatible with a number of standards at the source level, including IEEE POSIX.1, System V and BSD.

Other Linux-specific internal features include POSIX control (used by shells such as csh and bash), pseudo-terminals (pty), support for national and standard keyboards by dynamically loaded keyboard drivers.

The kernel itself can emulate 387-FPU instructions, so that systems without a coprocessor can execute programs that rely on it (i.e., floating point).

Linux supports various types file systems for data storage. Some file systems, such as the ext2fs file system, were created specifically for Linux. Other types of file systems are also supported, such as Minix-1 and Xenix. File-based MS-DOS system, which allows you to directly access MS-DOS files on your hard drive. The ISO 9660 CD-ROM file system is also supported for working with CD-ROM discs.

Linux provides a complete set of TCP/IP protocols for networking. The full range of TCP/IP clients and services is supported, such as FTP, telnet, NNTP and SMTP.

Linux kernel immediately created taking into account a special protected mode for Intel processors 80386 and 80486. In particular, Linux uses the protected mode memory description paradigm and other new features of processors.

To increase the volume of available Linux memory It also partitions the disk into pages: that is, up to 256 MB of “swap space” can be allocated on the disk. When the system needs more physical memory, it swaps inactive pages to disk. This allows you to run larger programs and serve more users at the same time. However, swapping does not exclude the expansion of physical memory, since it reduces performance and increases access time.

The kernel also supports a universal memory pool for user programs and disk cache. In this case, the entire memory can be used for the cache, and vice versa, the cache is reduced when large programs are running.

Executable programs use dynamically linked libraries, i.e. executable programs can share a library program represented by one physical file on disk. This allows executable files to take up less disk space, especially those that reuse library functions. There are also static linked libraries for those who want object-level debugging or have "complete" executable programs that don't need shared libraries. In Linux, shared libraries are dynamically linked at runtime, allowing the programmer to replace library modules with their own.

Linux is by far the most common free and open source operating system. source code. When developing it, we tried to take the best from the world of the UNIX family. Thanks to the participation of tens of thousands of software developers and the coordination of their actions through Internet Linux And software It develops very dynamically; errors and various problems in the software are usually corrected within a matter of hours after they are discovered. Great assistance in the development and distribution of Linux and related software was provided by the Free Software Foundation (USA) and the GNU license (The GNU General Public License) for software. Today there is one Linux kernel, the development of which is coordinated by its creators Linus Torvalds and Alan Cox, and many distributions (at least 2-3 dozen), differing both in functionality and in the composition of the software included in the distribution. There are distributions that take up a dozen CDs, and distributions that fit on one or two floppy disks. Everything that is true for the UNIX family is also true for Linux. Widest support for hardware platforms, low demands on hardware resources (486 processor, 8 MB random access memory, hard drive 120 MB). Scalability, support for multiprocessor systems, clustering, support for distributed computing, dozens of graphical shells - and that's not all. Dozens of file systems are supported, native Ext2 file system. And with all its power, it is a fairly user-friendly operating system, capable of running both on a very powerful server and on an old Pentium somewhere in the office.

Linux is a full-fledged operating system, which is a free clone of the operating system UNIX systems. In this article we will try to make technical Linux description.

When the computer boots, the Linux operating system takes over control of the computer and manages the following components.

Basic description of Linux components

• Processor - Since the Linux kernel allows multiple processes to run simultaneously from multiple users (with support for multiple processors), the operating system needs multithreading controls. The Linux scheduler assigns priorities to processes and determines which process is running on a particular processor (if the system has multiple processors). The scheduler can be configured to work on systems various types. At correct setting More important processes get faster CPU response. For example, the Linux scheduler on a desktop computer gives higher priority to the window moving task and lower priority to the background file copying task.
• Memory - the Linux kernel tries to keep things running in this moment processes in RAM. Idle processes are moved to the page file, which is a dedicated area on the hard drive that is used to store data and processes that are not moved into RAM. When the RAM becomes full, processes are moved to the paging file. If the paging file is full (but this should not be allowed), new processes will not start.
• Devices - The Linux kernel supports thousands of hardware devices. At the same time, by including only current drivers in the running kernel, the kernel size can be maintained at an acceptable level. Using loadable modules allows you to add support for additional devices to the kernel. Modules can be loaded and unloaded on demand as a result of connecting or disconnecting a device. (The kernel, which will be discussed next, is the heart of the Linux operating system.)
• File systems - file systems provide the structures in which files are stored on CD-ROMs, hard drives, floppy disks, DVDs and other media. The Linux kernel supports many types of file systems (for example, Linux file systems: ext3 and reiserfs, as well as VFAT and NTFS file systems from the operating system Windows systems).
• Security - like UNIX, the Linux operating system was originally created to provide simultaneous multi-user access. To protect user resources, each file is assigned sets of read, write, and execute permissions that define access rights. In a standard system, Linux has unrestricted access to the entire system, special logins can control specific services (such as Apache Web server services), and users can be assigned permissions individually or as part of groups. Recent innovations such as Security-Enhanced Linux support more fine tuning and protecting secure information processing environments.

Shown above description is a description of the basic components of the kernel Linux. The name from the Linux kernel (which was created and is still being developed under the leadership of Linus Torvalds) extended to the entire operating system.

The kernel is a software component that interacts directly with the computer hardware. Other components added to the core, such as administration tools and applications, are taken from other open source projects. The Linux kernel and the necessary components make up a complete operating system.

The next part in the article about describing Linux tells that many other components were created by other projects, so the correct way to pronounce Linux is: GNU Linux

The GNU Project contributed many components that are now part of the Linux operating system. (GNU, Apache, KDE, GNOME, and other key open source projects within Linux operating systems are discussed below.) The following subsystems were created from other projects.

• GUI user consists of a graphics infrastructure (usually the X WindowSystem), window managers, panels, icons and menus. The GUI allows you to use a combination of mouse and keyboard instead of simply entering commands from the keyboard (as was done in the good old days). In the near future, the X graphical server will be replaced by Wayland on all Linux distributions. Ubuntu is developing its own graph. server Mir.
• Administration tools include hundreds (and possibly thousands) of commands and graphical utilities that allow you to add users, manage disks, monitor network status, install software, and ensure security and manage computer resources.
• Applications - although none of them Linux distributions does not contain all existing applications, but each contains thousands of games, office applications, Web browsers, media players, chat clients and many other applications available exclusively for the Linux platform.
• Developer tools include exclusively tools for developing and creating libraries and applications to implement custom interfaces.
• Server capabilities allow the computer to Linux control provide services to clients on the network. In other words, in addition to installing Web browsers to view Web pages, a computer can be turned into a server that provides Web pages to other computers. At the same time, among the popular server functions we can name Web servers, servers Email, databases, printing, file servers, DNS servers and DHCP.

There are many different ones and one of them is Linux. What is it and where is it used? How is it structured? What differences are there from the Windows that most people are used to? "Linux"? All these questions will be answered within the article.

What is Linux

This is the operating system relative to which you have wide choose on the software that will be installed. In it you can choose between several types of desktops and about a dozen shells for command line. The latter, by the way, is called a terminal and plays a very important role. Thanks to its focus on executing several programs at once, the operating system is relatively less prone to failures. Due to the fact that no program can run by default without the user's knowledge, it is very difficult (although not impossible) to encounter a virus written under Linux. But if they infect computers, it is solely because the user launched a suspicious application. Some samples of this system can be easily placed and operated via optical drives or USB.

Development history

Linux in Russian sounds like “Linux”, that is, it is not translated. Do you know why this is so? This is due to the fact that it is named after its pioneering founder, Linus Torvalds. He presented his creation to the public in 1994 (although development began back in 1991). Due to the fact that the operating system was open source and anyone could modify it, he gained followers all over the world. Various companies that produce paid distributions are beginning to become interested in it. At the same time, communities of developers are emerging who create and distribute their builds on a volunteer basis. And as of 2016, there are about a dozen popular versions of Linux operating systems. What does this state of affairs tell us? This means that there is strong competition, mutual assistance (no matter how strange it may sound) and diversity. In addition to popular versions, less common ones are also widely used, which are often aimed at performing a specific range of tasks. And now, if you are interested in Russian Linux, know that downloading it is not a problem. And for others there are localizers that will translate at least some of the symbols.

Linux and Windows: what are the differences?

At first glance, the data does not look much different. But that's not true. There are differences, but to see them, you need to look “deeper.” The main focus will be on Linux, but to give you an idea of ​​what and how, a comparison will be made with Windows. We will consider:

1. File system.
2. Graphic shell.
3. System configuration.
4. Scope of application.

And finally, a little attention will be paid to distribution kits.

File system

First of all, it should be noted that no hard drives in the usual sense in Linux. What is the first thing that this state of affairs tells you? Difficult? Not at all! Logical partitions and physical disks will be preserved, only here they will be represented by directories. The operating system connects to some folder, and everything that is created ends up in it. Work can only be done with the files that are in it. The most important folder is the root one. It is denoted by /. For example, user files are typically stored in /home/username/. But you can change the location of almost anything you want if you wish. Is it difficult to move around such a structure?

Graphic shell

At first, after Windows, it may seem that moving is inconvenient. But this is only when using the terminal. There are also graphical shells with which you can work with the familiar interface. The terminal, by the way, is used either on servers or by very advanced people with good memory. The graphically designed shell is suitable for everyone else, as well as those who simply do not want to remember exact catalogs of information. The Linux system can appear in a variety of forms. Several desktop options can be configured, and the graphic design for them comes in hundreds of variations.

Configuration

U Windows given information is in system registry, which is a specific database. It is necessary so that programs launched in the operating system are configured correctly when they are loaded and at the beginning of their work. In it, if the registry is damaged, then only a complete reinstallation will help. Although there is an advantage to this - everything is in one place. But Linux took a different path. In it, each program has a separate configuration file (and sometimes even several). They can be viewed or edited at will text editor. If there are several files, then this has its advantages - if one of them is damaged, only part of the work will be lost. And reinstall in worst case You only need a separate program. When the user decides to change the computer he is using, he does not have to start all over again. He can simply copy the necessary files between machines (directly or using media). What to do if the operating system is damaged? This is an important advantage that Linux has. The operating system needs to be reinstalled, and you need to do it. But the file settings will be saved after this process and will not be lost. Although there is one small drawback - each program has its own format configuration files, and you will need to have a good understanding of what and how before editing.

Areas of application

We talked about this and how it differs from the Windows system familiar to most users. Now let's pay attention to the areas of its use. Unfortunately, it will not find application everywhere. So, Linux server or home/office work station- here it is close to ideal. The fact is that there are not many ported or created games for this operating system. There are also separate programs that run Adobe graphics packages and complex engineering programs(like AutoCAD, MatLAB and the like). But with the help of emulation this problem in most cases it can be solved. People do not always need a computer that solves specific problems. Therefore, I suggest that you familiarize yourself with a short list of the system’s capabilities, and if it does what you need, you can try it in practice and not be disappointed:

1. The system can create office documents, spreadsheets, various documentation and process texts.
2. It is possible to view and edit images and photographs.
3. You can listen to music and watch videos.
4. You can play games on the system - but usually very simple ones.
5. Realize communication processes via the Internet (in this regard, Linux is head and shoulders above Windows).
6. Convenient to program.
7. You can explore the Internet.
8. It is convenient to remotely manage operating systems (any).
9. Various messaging programs and email are available.
10. File sharing is conveniently implemented.
11. Free operating system
12. And finally, viruses here exist as a myth. At least the author has not met one in his entire life.

About distributions

Do you already want Russian Linux? Then it is necessary to say a little about distributions. On the one hand, it’s difficult to say that we have different operating systems. But on the other hand, no one will prove otherwise. You can choose the desired language and geographic focus, which will help make Linux more convenient. Russian version, French, Brazilian - the choice is yours. With the help of the operating system, you can seriously study foreign languages. But let's talk about distributions. Their main differences are the location of the programs in the file system. It cannot be said that one distribution is more convenient than another. It all depends on the tasks that you face. So, you can install one version in which you can only program, and there is weak Internet support (only text components are loaded). This option is suitable for those who cannot concentrate on work and are constantly distracted. There are also those that will allow you to best adjust the power to get optimal machine performance. There are a lot of choices, and it’s up to you to choose one of them.

The main difference between the OS Linux from family operating systems Windows is a qualitatively different type of file system organization. If in OS Windows the user deals with a disk file system, i.e. accesses logical drives C, D, E... and uses file system types such as FAT16, FAT32, NTFS, then in operating systems UNIX-families, including Linux, no logical drives. Organizing the file system in Linux built on the delimitation of so-called partitions ( partitions) – parts of the total space of a hard disk (hard drive), access to data on which is possible by selecting a designated file system directory, and the types of file systems are EXT2 And EXT3. The difference between the above file systems lies in the different level of security for storing data. Flexible way to assign partitions Linux implements effective management of operating system security, allowing some users to assign access to data, but not others.

Modern operating systems. Advantages, qualitative comparison and functional features of OS

OS UNIX-families satisfy all the requirements imposed on them by VLSI development tools: this is the ability to provide simultaneous access to development tools for many users; high speed of information processing; availability of a set of text and graphic editors, tools for reading help files and internal CAD documentation; set of programs for network access on the Internet and other networks; a set of tools for remote work with CAD; a wide variety of useful programs and utilities for working with audio, video and photo objects, as well as much more. In addition, an important component of operating systems of this family is the presence of a command interpreter capable of processing user command requests and displaying the received information on the monitor screen, in a file or on a device.

OS development process UNIX was carried out by computer professionals working in a scientific environment. As UNIX developed, it provided the basis for various operating systems, among which the most famous are Linux, Solaris And FreeBSD. Each of these systems began to develop individually, but retained all the advantages UNIX.

The most used operating system of the family UNIX is Linux. This platform has a user-friendly graphical interface that allows the user to more comfortably control the OS using not only a keyboard, but also a mouse-type device. Among the main advantages of Linux are:

1. flexibility;

2. power;

3. stability;

4. multitasking mode;

5. multi-user mode;

6. high level of security;

7. convenient graphical interface;

8. a large number of text and graphic programs;

9. a set of client and server applications;

10. Availability of an “open license”.

OS Linux conveniently combines high system performance and the ability to fine-tune system elements to the needs of a specific developer. Qualified configuration of the operating system functions allows it to work around the clock for a long time without interruption. The presence of multi-user and multi-tasking modes, together with a high level of OS security, allows developers to use many CAD applications simultaneously, without the threat of losing or damaging their data. High stability, along with the high power of the operating system, allows you to reliably serve user requests on a mid-range hardware and computing platform.

No less important advantage Linux is the presence of a so-called “open license” for most distributions. Although the source code of some software is openly distributed and free, it is protected by public licenses, which exclude the right of commercial companies to slightly modify it and claim copyright on these changes, and then take control of the software product and sell it as their own. The most popular is the public license GNU Public License provided by the Free Software Foundation ( Free Software Foundation). The Linux operating system is distributed under this license. General Public License GNU reserves copyright to the developer, but guarantees free use of the software, provided that the software itself and all additions and changes to it will always remain freely distributable.

When working with Linux The VLSI developer has the ability to launch programs both from the main computer, at which he is directly located, and from a remote computer, working with it through his terminal. IN Linux it is possible to customize the required type, size and color of fonts as desired; background color terminal window; team invitation display form; set the necessary variables and aliases. The developer can control the processes, change the priority between them as necessary, and remove some.

Did you know, What is the falsity of the concept of “physical vacuum”?

Physical vacuum - the concept of relativistic quantum physics, by which they mean the lowest (ground) energy state of a quantized field, which has zero momentum, angular momentum and other quantum numbers. Relativistic theorists call a physical vacuum a space completely devoid of matter, filled with an unmeasurable, and therefore only imaginary, field. Such a state, according to relativists, is not an absolute void, but a space filled with some phantom (virtual) particles. Relativistic quantum theory fields states that, in accordance with the Heisenberg uncertainty principle, virtual, that is, apparent (apparent to whom?), particles are constantly born and disappeared in the physical vacuum: so-called zero-point field oscillations occur. Virtual particles of the physical vacuum, and therefore itself, by definition, do not have a reference system, since otherwise Einstein’s principle of relativity, on which the theory of relativity is based, would be violated (that is, an absolute measurement system with reference to the particles of the physical vacuum would become possible, which in turn would clearly refute the principle of relativity on which the SRT is based). Thus, the physical vacuum and its particles are not elements of the physical world, but only elements of the theory of relativity, which do not exist in the real world, but only in relativistic formulas, while violating the principle of causality (they appear and disappear without cause), the principle of objectivity (virtual particles can be considered, depending on the desire of the theorist, either existing or non-existent), the principle of factual measurability (not observable, do not have their own ISO).

When one or another physicist uses the concept of “physical vacuum,” he either does not understand the absurdity of this term, or is disingenuous, being a hidden or overt adherent of relativistic ideology.

The easiest way to understand the absurdity of this concept is to turn to the origins of its occurrence. It was born by Paul Dirac in the 1930s, when it became clear that denying the ether in its pure form, as was done by a great mathematician but a mediocre physicist, was no longer possible. There are too many facts that contradict this.

To defend relativism, Paul Dirac introduced the aphysical and illogical concept of negative energy, and then the existence of a “sea” of two energies compensating each other in a vacuum - positive and negative, as well as a “sea” of particles compensating each other - virtual (that is, apparent) electrons and positrons in a vacuum.