Introduction to Linux Technologies

Over time, Linux, an open-source operating system, has grown significantly in popularity and usage.  The foundations of Linux technology, its origins, distributions, advantages, kernel, command-line interface (CLI), graphical user interface (GUI), file system, package management, shell scripting, and applications that it supports in different settings will all be discussed in this article.

This article will give you a thorough introduction to Linux technology, whether you are brand-new to Linux or just want to learn more.

What is Linux Operating System?

Linux is a series of open-source operating systems that are based on the Linux kernel. Linus Torvalds was the first person to publish the Linux kernel, which was released on September 17, 1991. In most cases, Linux is packaged as the Linux distribution, which includes the kernel, as well as an assortment of supporting libraries and system software. The GNU Project is responsible for providing a number of these components. There are a few Linux distributions that use the term “Linux” in their titles, but the Free Software Foundation uses the designation “GNU/Linux” to emphasize the importance of GNU software, which has resulted in a few disagreements.

Among the most well-known Linux distributions are Ubuntu, Fedora Linux, and Debian. Debian is a collection of various different modifications and distributions, including Xubuntu and Lubuntu, among others. The SUSE Linux Enterprise and Red Hat Enterprise Linux distributions are examples of commercial distributions. Windowing systems such as Wayland or X11, as well as desktop environments such as KDE Plasma and GNOME, are examples of desktop distributions of the Linux Operating System.

• The Linux operating system was initially developed for personal computers and was based on the Intel x86 architecture. However, since its inception, Linux has been adapted to a wider range of contexts than other operating systems.
• Linux, which includes Android, has the largest installed base of any general-purpose operating system. This is due to the fact that Android, which is built on Linux, holds control over smartphones as of May 2022.
• On the other hand, as of November 2022, Linux is only utilized by only 2.6% of desktop computers.
• Additionally, Linux is able to run on a wide variety of embedded systems, which are devices in which the operating system is often built into the firmware and is exceedingly tailored to the system.
• Spacecraft (such as the Perseverance rover, the Dragon crew capsule, and the Falcon 9 rocket), automobiles (such as Toyota, Hyundai, Mercedes-Benz, Audi, and Tesla), televisions (such as LG and Samsung Smart TVs), video game consoles, smart home gadgets, automation controllers, and routers are all included in this category.

The open-source and free software collaboration that is Linux is one of the most remarkable examples of this type of software; in accordance with the terms of its individual licenses, such as the GNU General Public License (GPL), the source code may be distributed, updated, and used by anyone, whether for non-commercial or commercial purposes. Taking the Linux kernel as an example, it is licensed under the GPLv2 license.

The History of Linux

The original iteration of the Linux kernel was created in the early 1990s by a Finnish computer science student named Linus Torvalds.  Since that time, Linux has developed thanks to the efforts of a large development ecosystem on a global scale to become a strong and adaptable operating system used on a variety of platforms.

Precursors

At the Bell labs of AT&T in the United States, Joe Ossanna, Douglas Mcllroy, Dennis Ritchie, and Ken Thompson were the individuals responsible for the implementation and conception of the Unix-based operating system in the year 1969. The first version of Unix, which was released in 1971, was written entirely in assembly code, which was the standard writing method at the time. In 1973, Dennis Ritchie made a significant and pioneering contribution by updating it in the C programming language. The fact that a high-level language implementation running on Unix was readily available made the process of porting it to different computer platforms more convenient.

Creation

While Torvalds was attending the University of Helsinki in the fall of the 1990s, he enrolled in a Unix class. The MicroVAX minicomputer that was used in the class was capable of running Ultrix, and one of the required textbooks was titled Operating Systems: Design and Implementation and was written by Andrews S. Tanenbaum. Tanenbaum’s MINIX operating system was included in the textbook as a copy of the software. It was in conjunction with this lesson that Torvalds first became receptive to the Unix operating system. The year 1991 marked the beginning of his interest in operating systems. As a result of his frustration with the licensing of MINIX, which at the time restricted its usage to educational purposes only, he began working on the kernel of his operating system, which would later become the Linux Kernel itself.

The development of the Linux kernel was initially begun by Torvalds on MINIX, and software that was originally created for MINIX was also utilized on Linux. Later on, Linux was developed, and this was followed by the appearance of the Linux kernel on Linux-based computers from the beginning. Additionally, GNU programs have replaced every MINIX component since it was advantageous to utilize the free code through the GNU Project with the new operating system. Code that is licensed under the GNU General Public License (GPL) can be re-applied in other computer functions as long as they are also published under a license that is compatible with or the same as the GNU GPL.

It was Torvalds who initiated the transition from his original license, which prohibited commercial distribution, to the GNU General Public License. The goal of the developers was to create a free and fully functional operating system by combining GNU components with the Linux Kernel.

Current development

In addition to directing the development of the Linux Kernel, Greg Kroah-Hartman is the primary maintainer of the Linux kernel. It was William John Sullivan who served as the executive director of the Free Software Foundation, which was responsible for providing support for the GNU components. Lastly, corporations and people alike are developing non-GNU third-party components.

It is possible for the third-party components to include user libraries and programs in addition to kernel modules. These components are made up of a vast body of work. The Linux community and vendors are responsible for the distribution and combination of the kernel, non-GNU components, and GNU components, along with additional package management tools, in the manner of Linux distributions.

Popular and commercial uptake

When it came to production environments, Linux adoption started to take off in the middle of the 1990s in the supercomputing community. At that time, the only people who used Linux were hobbyists. Organizations such as NASA began to gradually replace their expensive machines with inexpensive commodity computer clusters that ran Linux. IBM and Dell, with Hewlett-Packard’s assistance, began offering Linux support in an effort to break free from Microsoft’s stronghold on the desktop operating system market. This marked the beginning of the commercial use of Linux.

Linux systems have secured a position in server setups such as the well-known LAMP application stack, and they are used in every aspect of computing on the planet today, from embedded devices to practically every supercomputer. There has been a growing trend toward the utilization of Linux distributions in both business and personal PCs.

In addition, Linux distributions have gained popularity in the market for netbooks, as seen by the fact that a number of devices are going forward with customized Linux distributions installed on them and Google publishing ChromeOS, which was created specifically for netbooks.

Uses of Linux OS

There are several quantitative studies that focus on open-source and free software, with many of these research investigating Linux in particular. These studies focus on aspects such as reliability and marketplace share. The Linux industry is expanding, and it is anticipated that the size of the Linux operating system market will increase by 19.2% by the year 2027, reaching 15.64 billion dollars, which is a significant increase from the total of 3.89 billion dollars in 2019. Both advocates and experts believe that the success of Linux can be attributed to its freedom, low cost, reliability, and protection from being locked in by a single vendor.

The Linux operating system adheres to a standard design, which is the primary motivating factor for its many different distributions and modifications. Even though every Linux distribution is built on top of the Linux kernel, it might vary depending on factors such as:

• Kernel version: Distros can be set up with more recent releases to add new aspects or with previous releases to be more balanced.
• Kernel modules: This software can be unloaded and loaded into the kernel development functionality without restarting. Often, kernel modules are used for support:
  • Device drivers utilize code that manages how linked devices work.
  • File system drivers utilize code that manages how the kernel operates with distinct file systems.
  • System calls utilize code that manages how programs claim services through the kernel.
• Configuration options: Kernels unified with configuration options configured to add only file system or device drivers are used for a few specialized distributions, for instance, compiling the kernel for any wireless device without wired network device drivers.
  The kernel is the one thing that every system has in common running Linux. Linux operates by:
• Booting and loading the Linux kernel.
• The kernel handles every system output and input once booted. The system is booted, and processes can be initialized.
• The system can be utilized for processes that contain commands interactively entered by the command line, network server functions, desktop applications, or any program or application as system processes are booted.

The user experience can widely vary, depending on how the Linux system is being utilized, while the kernel may almost be identical with some compilation differences and divergence for configuration. For example, a few use cases of Linux with distinct user experiences are:

• Desktop productivity systems, like those utilized by software developers or several other professionals. The workstations of software development may be enhanced for performance, while desktops may be enhanced for the utilization of desktop productivity tools for administrative professionals.
• Network servers might not even add a command line window for direct access. Remotely, these headless servers are handled by Windows sessions or network terminals. Servers may be utilized by several but should only be accessed by authorized system admins.
• Thin clients let users utilize a rich desktop environment with a lightweight device. It includes Google Chromebooks and Raspberry Pi single-card systems.

Linux operates similarly to any GUI-based operating system when using it as a GUI with a desktop environment. Applications and many other resources can be launched by pressing icons, and files can be deleted, copied, or moved using a trackpad or mouse.

Usage of different OSes

Linux

In Linux, LKMs are loaded by using the modprobe command. LKMs are located in /usr/lib/modules and /lib/modules and have had the .ko (kernel object) extension since the 2.6 version. The command, i.e., lsmod, is used to list the kernel modules which are already loaded. In some serious cases, if the system doesn’t boot, e.g., due to broken modules, particular modules can be activated or deactivated by changing the list of the kernel boot parameters (e.g., if utilizing GRUB, by clicking ‘e’ inside the start menu of GRUB, then altering the kernel parameter line).

• Linuxant controversy

Linuxant, an advising company that published proprietary device drivers as kernel modules (loadable) in 2004, attempted to exploit a null terminator in the MODULE_LICENSE, as shown in the below code piece:

MODULE_LICENSE(“GPL\0for files in the \”GPL\” directory; for others, only LICENSE file applies”);

• License issues

LKM is kernel-derived works from the point of view of Linux maintainers. The Linux maintainers permit the distro of proprietary modules but permit symbols to be considerable as just available to GNU GPL modules.

Loading a non-GPL-compatible or proprietary module will fix a ‘taint’ flag inside the running kernel, which means that any bugs or problems experienced will likely be less likely to be inspected by the maintainers. Effectively, LKMs become an element of the running kernel, so they can produce bugs and kernel data structures that can’t be inspected if that module is proprietary indeed.

FreeBSD

For FreeBSD, kernel modules are stored in /boot/kernel/ for several modules shared with the OS, or basically /boot/modules/ for several modules inaugurated from FreeBSD packages or FreeBSD ports, or otherwise for binary-only or proprietary modules. Usually, FreeBSD kernel modules have the .ko extension. When the device has started, it might be loaded with a command, i.e., kldload, unloaded with the kldunload command, and listed with the kldstat command. Also, modules can be loaded through the loader before the kernel begins, either by hand or automatically (via /boot/loader.conf).

macOS

In macOS, a few loadable kernel modules can automatically be loaded. Also, loadable kernel modules can be loaded via the command, i.e., kextload. They can be shown by a command, i.e., kextstat. LKMs are placed in bundles using the .kext extension. Modules equipped with the OS are saved in the directory, i.e., /System/Library/Extensions; modules equipped by third parties are in many other directories.

NetWare

The NetWare kernel module is called an NLM (NetWare Loadable Module). NLMs are embedded into the NetWare kernel using the command, i.e., LOAD, and deleted by the command, i.e., UNLOAD. The command, i.e., modules, lists currently loaded kernel modules. NLMs may located in any accurate search path defined on the NetWare server and have .NLM is an extension of the file name.

VxWorks

A DKM (Downloadable kernel module) type project can be made to produce a file, i.e., .out, which can be loaded to the kernel space with the help of the “ld” command.

Solaris

Solaris includes a kernel module (configurable) load path that defaults to the directory, i.e., /platform/platform-name/kernel /kernel /usr/kernel. Almost every module resides in subdirectories upon the /kernel directory; those not acknowledged necessary to start the system that init can boot and are often found inside the /usr/kernel directory. When executing the DEBUG kernel, establish the system that tries to unload modules actively.

Binary compatibility

Linux doesn’t offer a stable ABI or API for kernel modules. It means there are many differences in function and internal structure between distinct kernel releases, which can lead to compatibility problems. Symbol versioning data is located inside the section, i.e., .modinfo, of ELF modules (loadable). This versioning data can be correlated to that of the active kernel before going to load a module; the modules can’t be loaded if the releases are incompatible.

Other OSes, including Windows, macOS, FreeBSD, and Solaris, keep the kernel ABI or API relatively stable, hence ignoring this issue. For instance, FreeBSD kernel modules unified against the 6.0 version of the kernel will operate without revision on other 6.x versions of FreeBSD, e.g., 6.4. However, they aren’t compatible with other releases and must be revised for use with the 7.x version of FreeBSD, as ABI and API compatibility is managed inside a branch only.

Security

While LKMs are a suitable way of changing the active kernel, they can be exploited by the attackers on an affected system to avoid detection of their files or processes, permitting them to manage control over a system. In this way, several rootkits use LKMs. Remember that, on almost every operating system; modules don’t aid privilege elevation in a way because elevated privilege is needed to load a loadable kernel module; they hardly make it convenient for the attacker to cover the break-in.

Linux

Linux permits deactivating module loading by sysctl option, i.e., /proc/sys/kernel/modules_disabled. A system called initramfs may load particular modules required for a device at the start and then deactivate module loading. It lets the security quite the same as a monolithic kernel. The attackers can modify the kernel binary if they can modify the initramfs.

macOS

A kernel extension needs to be code-signed using a developer certificate that contains a specific “entitlement” in OS X Yosemite and future releases. This type of developer certificate is only given upon Apple request and is not provided automatically to all members of Apple Developer. This aspect, known as “kext signing,” is activated by default and instructs the kernel to avoid booting if unidentified kernel extensions are available. It’s the System Integrity Protection part in OS X EI Capitan and future releases.

In a kernel extension bundle, an LKM can be loaded using non-root users if the property, i.e., OSBundleAllowUserLoad, is fixed to true inside the property list of the bundle in older releases of macOS or when kext signing is deactivated. However, if the files within the bundle, such as the executable code file, aren’t owned via group and root wheel or are specifiable via the “other” or group, the attempt to load the LKM will fail.

Solaris

Optionally, kernel modules can contain an ELF cryptographic signature section that is authenticated on load, relying on the policy settings of the Verified Boot. The kernel can accomplish this by allowing modules to be signed cryptographically by a group of trusted certificates. Userspace started kernel module loading is possible only through the Trusted Path if the system is active with the feature, i.e., Immutable Global Zone, enabled.

Linux Distributions

Linux distributions, or distros as they are commonly known, are various varieties of Linux that bundle the Linux kernel with a selection of programs and applications.  Several well-known Linux distributions are CentOS, Fedora, Ubuntu, and Debian.  These distributions offer a variety of functions and software packages to accommodate various user demands and tastes.

Ubuntu	Based on Debian, Ubuntu is a user-friendly Linux distribution. It has a robust graphical user interface (GUI) and is frequently used for desktop computing. Ubuntu is a well-liked option for newcomers since it places a strong emphasis on usability and accessibility.
Fedora	Red Hat supports Fedora, a Linux distribution that is fueled by community input.  It places a focus on modern-day technology and is frequently utilized by players and developers.  Fedora is appropriate for both workstation and server settings because it strikes an equilibrium between stability and fresh capabilities.
Debian	One of the first and most well-known Linux distributions is Debian.  It is an increasingly common choice for servers and mission-critical systems because it places a high priority on reliability and security.  Debian has a huge library of software packages and a clear preference for free and open-source applications.
CentOS	Red Hat Enterprise Linux (RHEL)’s source code served as the foundation for the Linux distribution known as CentOS.  It aspires to offer a long-term supported, free, enterprise-class OS.  In server settings where dependability and stability are essential, CentOS is extensively utilized.

Pros and Cons of Linux OS

Numerous advantages that Linux provides help to fuel its rising appeal across multiple industries.  Knowing these advantages will assist in clarifying why Linux is used so frequently in various settings.

Some benefits of using Linux are listed and explained below:

Open source	The Linux kernel is published under the open-source software license of GNU GPL. Most distributions contain several applications with various options in almost all categories. Also, several distributions contain proprietary software, like device drivers offered by manufacturers, to support hardware.
Reliability	Linux is treated as a reliable operating system, and it is well-supported with several security patches. Also, Linux is treated as a stable OS, which means it can execute in almost every circumstance. Linux can also handle errors when running unexpected input and software.
Licensing costs	Linux has no accurate licensing fees, unlike Apple macOS or Microsoft Windows. While system support is present for a fee from several Linux vendors, the operating system itself is free to use and copy. A few IT organizations have enhanced their savings by moving their server software to Linux from a commercial operating system.
Backward compatibility	Linux and many open-source software tend to be frequently updated for functional and security patches while having core functionality. Shell scripts and configurations are likely to operate unchanged even if software updates are used. Generally, Linux and other open-source applications do not alter their operation modes with new versions, unlike economic software vendors that mount new releases of their operating systems with new forms of work.
Several choices	Between almost all infinite options, several available distros, and many application options to configure, compile, and run Linux on almost all hardware platforms, it’s possible to develop Linux for almost all applications.

In this regard, there are some other benefits available, such as:

• Security: Because of its sophisticated safety characteristics, Linux is well known.  Due to the fact that it is open-source, security flaws can be swiftly found and fixed by members of the community.  Furthermore, Linux has built-in safety measures, including encryption, firewalls, and file permissions.
• Stability: Linux has a reputation for being exceptionally stable. The kernel is built to effectively manage many processes, reducing errors and failures in the system.  Linux systems can operate continuously for long periods of time without the requirement for a reboot.
• Customizability: Linux’s great level of customizability is one of its main benefits.  Users are free to personalize and adjust their Linux distributions to suit their unique requirements and interests.  Users who have possession of the source code can customize and improve their Linux systems to meet their needs.
• Cost-effectiveness: In comparison to commercial operating systems, Linux is a more affordable option. Since the majority of Linux distributions have no cost, there is no longer a need for high licensing fees.  Additionally, Linux functions well on outdated hardware, enabling businesses to increase the service life of their current systems without incurring expensive hardware upgrades.

A few drawbacks of Linux are:

• Lack of standard: No standard version is available for Linux, which may be nice to optimize Linux for specific applications, but less so to deploy desktop images and standardized servers. The huge variety of options can convolute support as an outcome.
• Support costs: Support isn’t free, while an organization can freely acquire Linux without licensing fees. Almost all enterprise Linux distributors, such as Red Hat and SUSE, provide support contracts. These license fees can significantly decrease savings depending on the situation.
• Proprietary software: PC productivity software, such as Microsoft Office, can’t be utilized on Linux desktops, and many proprietary software may not be available for Linux platforms.
• Steep learning curve: Several users battle to learn to use Linux-based applications and Linux desktops.
• Unsupported hardware: Several hardware manufacturers enable the device drivers of Linux accessible for their products, but several don’t.

Linux Kernel

The Linux kernel is the foundation of every Linux distribution.  The administration of system resources, support for hardware, and interaction between hardware and software elements are all tasks that the kernel is in charge of.  It supports the operating system’s efficiency and functionality and acts as its structural backbone.

Linux Distributions

Linux has accepted the copyleft provisions of the Free Software Foundation, which produced the GNU GPL since its start in development. The GPL describes that anything taken for modification and free must be freely distributed.

Hundreds of Linux versions, also called distros or distributions, are available. Usually, distributions differentiate themselves through the pack by defining a specific goal, target market, function, or philosophy.

There are many distributions made for particular target functions, like security, gaming, desktops, servers, or embedded devices, such as Raspberry Pi systems. Almost every modern distribution is ready to use and precompiled, while others, such as Gentoo Linux, are composed of source code that any user can locally compile during starting installation to use their system configuration.

Command-Line Interface (CLI)

The robust command-line interface (CLI) provided by Linux enables users to communicate with the operating system using text-based commands.  The CLI offers sophisticated control and flexibility, allowing individuals to carry out difficult operations, automate procedures, and effectively manage the system.

Graphical User Interface (GUI)

Linux distributions also include a user interface called a graphical user interface (GUI) for individuals who want an appealing user interface.  With its icons, windows, and menus, the GUI provides an easy-to-use interface that makes it simpler for novices to traverse and communicate with the system.  Linux GUIs are available in a variety of flavors, including GNOME, KDE, and Xfce, each of which offers a unique user experience.

Linux File System

Linux uses a hierarchy file system to arrange directories and files in a tree-like form.  The initial location is the root directory (“/”), from which subdirectories branch out.  This file system makes it possible to store, handle, and retrieve data quickly while maintaining its confidentiality and availability.

Package Management

Package management systems are used by Linux distributions to make it easier to install, update, and remove software packages.  Such package administrators offer an organized and effective approach to handling software, dependencies, and system upgrades.  Examples include APT (Advanced Package Tool) and YUM (Yellowdog Updater, Modified).

Linux Shell and Shell Scripting

Users can communicate with the operating system using the Linux shell, which is an interpreter for commands.  It offers a command-line interface through which users may run programs, enter commands, and automate operations.  Shell scripting enables the automated execution of intricate procedures and the development of unique workflows by allowing users to write scripts that combine several commands.

Linux in Server Environments

Due to its reliability, safety, and flexibility, Linux has an important role in server settings.  Operating systems based on Linux are used on numerous web servers, database servers, and cloud servers.  Linux is a great option for delivering crucial applications and services due to its durability and productivity.

Linux in Embedded Systems

In the case of embedded systems, typically specific computer systems built into different devices and gadgets, Linux is frequently utilized.  For executing embedded applications, Linux offers a compact and adaptable platform, making it popular in sectors including automotive, telecommunications, and healthcare.

Linux in IoT (Internet of Things) Devices

Linux is essential for running IoT devices as the Internet of Things (IoT) expands.  It is appropriate for a variety of IoT applications, ranging from smart homes and wearables to industrial automation and agriculture, due to its adaptability, minimal demands on resources, and comprehensive driver support.

Linux in Cloud Computing

Several cloud computing platforms and infrastructures are built on Linux. It is a favored option for creating cloud environments due to its scalability, dependability, and affordability.  Many cloud services, such as virtual machines, containers, and serverless computing, are powered by Linux-based operating systems, allowing companies to make use of the advantages of cloud computing.

FAQs

About Introduction to Linux Technologies

1: Is Linux difficult to learn for beginners?

Beginners may find it challenging to learn Linux, particularly if they are unfamiliar with the interfaces on the command line.  Still, there are many accessible packages and materials to aid newbies in getting started and progressively gaining skills.

2: Can I install Linux alongside my existing operating system?

Yes, dual-booting is supported by the majority of Linux distributions.  Thus, you are able to install Linux with your existing operating system and decide which to boot into at launch.  However, it’s crucial to back up your information and to pay close attention to installation guidelines.

3: Are there paid versions of Linux?

Even though Linux is a free and open-source operating system, some businesses sell Linux variants that include more features, support, and services.  Red Hat Enterprise Linux (RHEL) and SUSE Linux Enterprise are two examples.

4: Can I run Windows applications on Linux?

Linux comes with a broad choice of software applications already installed. However, compatibility levels like Wine or virtualization programs like VirtualBox or VMware could be needed to run Windows programs natively on Linux.

5: Is Linux only for programmers and technical users?

Linux is not just for computer geeks and developers.  Even though it has a wide range of developer-friendly features,  Linux is usable by people with different backgrounds in technology because of its user-friendly variants with graphical user interfaces.

Conclusion

In summary, Linux technologies have completely changed the operating system industry.  With its open-source philosophy, reliability, safety, and flexibility, Linux has become widely used in a variety of industries.  A major part of what makes Linux a flexible and potent operating system is its kernel, command-line interface (CLI), graphical user interface (GUI), file system, package management, and shell scripting.  In addition to its effect and reach, Linux discovers apps for server settings, embedded systems, IoT devices, and cloud computing.  Understanding the fundamentals of Linux technology is crucial in today’s digital world, regardless of your level of experience.

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