Linux Fundamental

The  command line interface (CLI)  is a simple text input system for entering anything from single-word commands to complicated scripts. Most operating systems have a CLI that provides a direct way of accessing and controlling the computer. On systems that boot to a GUI, there are two common ways of accessing the command line—a GUI-based terminal, and a virtual terminal: ·          A GUI terminal is a program within the GUI environment that emulates a terminal window. GUI terminals can be accessed through the menu system. For example, on a CentOS machine, you could click on  Applications  on the menu bar, then  System Tools  > and, finally,  Terminal . If you have a search tools, you can search for  terminal , as shown here. ·          A virtual terminal can be run at the same time as a GUI but requires the user to log in via the virtual terminal before they...

  Navigating the Linux Desktop To be a Linux systems administrator, it is necessary to be comfortable with Linux as a desktop operating system and have proficiency with basic Information and Communication Technology (ICT) skills. Using Linux for productivity tasks, rather than depending on Windows or Macintosh systems, accelerates learning by working with Linux tools on a daily basis. Systems administrators do far more than manage servers; they are often called upon to assist users with configuration issues, recommend new software, and update documentation among other tasks. Most Linux distributions allow users to download a “desktop” installation package that can be loaded onto a USB key. This is one of the first things aspiring system administrators should do; download a major distribution and load it onto an old PC. This process is fairly straightforward, and tutorials are available online. The Linux desktop should be familiar to anyone who has used a PC or Macintosh with ic...

Linux started out as something that would only run on a computer like Linus Torvald's: an Intel 386 PC with a specific hard drive controller, but since anyone could add to or change Linux, people started building support for other hardware. Eventually, Linux started supporting other chips with an emphasis on small size and low power consumption. Because of this flexibility, a significant number of device makers have used Linux as the operating system for their hardware products. Today we call these  embedded systems  because they are designed to do a specific task on hardware optimized for only that purpose. These systems encompass a tremendous diversity of devices that are used today, from cell phones to smart TVs and appliances, to remote monitoring systems for pipelines and factories. As Linux evolved, specialized processor chips were developed for consumer and industrial devices to take advantage of its capabilities. Support for Linux has become so ubiquitous that it i...

Red Hat Red Hat  started as a simple distribution that introduced the Red Hat Package Manager (RPM). The developer eventually formed a company around it, which tried to commercialize a Linux desktop for business. Over time, Red Hat started to focus more on the server applications, such as web- and file-serving and released  Red Hat Enterprise Linux (RHEL) , which was a paid service on a long release cycle. The release cycle dictates how often software is upgraded. A business may value stability and want long release cycles, while a hobbyist or a startup may want the latest software and opt for a shorter release cycle. To satisfy the latter group, Red Hat sponsors the  Fedora Project  which makes a personal desktop comprising the latest software but is still built on the same foundations as the enterprise version. Because everything in Red Hat Enterprise Linux is open source, a project called  CentOS  came to be. It  recompiled  all the RHEL pa...

Linux users typically obtain an operating system by downloading a  distribution . A Linux distribution is a bundle of software, typically comprised of the Linux kernel, utilities, management tools, and even some application software in a package which also includes the means to update core software and install additional applications. The distribution takes care of setting up the storage, building the kernel and installing hardware drivers, as well as installing applications and utilities to make a fully functional computer system. The organizations that create distributions also include tools to manage the system, a package manager to add and remove software, as well as update programs to provide security and functionality patches. The number of Linux distributions available numbers in the hundreds, so the choice can seem daunting at first. However, the decision points are mostly the same as those highlighted for choosing an operating system. Role With Linux, there are mul...

Apple  makes the  macOS  operating system, which is partially based on software from the FreeBSD project and has undergone UNIX certification. macOS is well known for being “easy to use”, and as such has continued to be favored by users with limited access to IT resources like schools and small businesses. It is also very popular with programmers due to its robust UNIX underpinnings. On the server side,  macOS Server  is primarily aimed at smaller organizations. This low-cost addition to macOS desktop allows users to collaborate, and administrators to control access to shared resources. It also provides integration with iOS devices like the iPhone and iPad. Some large corporate IT departments allow users to choose macOS since users often require less support than standard Microsoft productivity deployments. The continued popularity of macOS has ensured healthy support from software vendors. macOS is also quite popular in the creative industries such as graph...

Microsoft  offers different operating systems according to the machine’s role: desktop or server? The desktop version of Windows has undergone various naming schemes with the current version (as of this writing) being simply  Windows 10 . New versions of this OS come out every 3-5 years and tend to be supported for many years. Backward compatibility is a priority for Microsoft, even going so far as to bundle virtual machine technology so that users can run older software. Windows Server  currently (as of this writing) is at version  2019  to denote the release date. The server can run a GUI but recently Microsoft, largely as a competitive response to Linux, has made incredible strides in its command line scripting capabilities through PowerShell. There is also an optional Desktop Experience package which mimics a standard productivity machine. Microsoft also actively encourages enterprise customers to incorporate its Azure cloud service.  

Role The first decision when specifying any computer system is the machine’s role. Will you be sitting at the console running productivity applications or web browsing? If so, a familiar  desktop  is best. Will the machine be accessed remotely by many users or provide services to remote users? Then it’s a  server . Servers typically sit in a rack and share a keyboard and monitor with many other computers, since console access is generally only used for configuration and troubleshooting. Servers generally run as a CLI, which frees up resources for the real purpose of the computer: serving information to clients (any user or system that accesses resources remotely). Desktop systems primarily run a GUI for the ease of use of their users. Function Next, determine the functions of the machine. Is there specific software it needs to run, or specific functions it needs to perform? Will there be hundreds, even thousands, of these machines running at the same time? What is...

An  operating system  is software that runs on a computing device and manages the hardware and software components that make up a functional computing system. Modern operating systems don’t just manage hardware and software resources, they schedule programs to run in a multi-tasking manner (sharing the processor so that multiple tasks can occur apparently simultaneously), provide standard services that allow users and programs to request something happen (for example a print job) from the operating system, and provided it’s properly requested, the operating system will accept the request and perform the function needed. Desktop and server operating systems are by nature more complex than an operating system that runs on a single-purpose device such as a firewall, or a mobile phone. From a simple set-top box that provides a menu interface for a cable provider, to supercomputers and massive, parallel computing clusters, the generic term  operating system  is used t...

There are two basic types of interfaces available that allow you to interact with the operating system. The typical computer user today is most familiar with a  graphical user interface (GUI) . In a GUI, applications present themselves in windows that can be resized and moved around. There are menus and tools to help users navigate. Graphical applications include web browsers, graphics editing tools and email, to name a few. Below is an example of a graphical desktop, with a menu bar of popular applications to the left, a LibreOffice document being edited in the foreground and a web browser in the background. The second type of interface is the  command line interface (CLI) , a text-based interface to the computer. The CLI relies primarily on keyboard input. Everything the user wants the computer to do is relayed by typing commands rather than clicking on icons. It can be said that when a user clicks on an icon, the computer is telling the user what to do, but, when the ...

People that say their computer runs Linux usually refer to the kernel, tools, and suite of applications that come bundled together in what is referred to as a  distribution . Take Linux and the GNU tools, add some user-facing applications like a web browser and an email client, and you have a full Linux system. Individuals and even companies started bundling all this software into distributions almost as soon as Linux became usable. The distribution includes tools that take care of setting up the storage, installing the kernel, and installing the rest of the software. The full-featured distributions also include tools to manage the system and a  package manager  to help you add and remove software after the installation is complete. Like UNIX, there are distributions suited to every imaginable purpose. There are distributions that focus on running servers, desktops, or even industry-specific tools such as electronics design or statistical computing. The major players ...

Historically, most software has been issued under a closed-source license, meaning that you get the right to use the machine code, but cannot see the source code. Often the license explicitly says that you may not attempt to reverse engineer the machine code back to source code to figure out what it does! The development of Linux closely parallels the rise of  open source software . Open source takes a source-centric view of software. The open source philosophy is that you have a right to obtain the software source code and to modify it for your own use. Linux adopted this philosophy to great success. Linus made the source programming code (the instructions a computer uses to operate) freely available, allowing others to join in and shape this fledgling operating system. It was not the first system to be developed by a volunteer group, but since it was built from scratch, early adopters could influence the project’s direction. People took the source, made changes, and shared th...

The definition of the word Linux depends on the context in which it is used. Linux means the  kernel  of the system, which is the central controller of everything that happens on the computer. When most people refer to Linux, they are really referring to a combination of software called  GNU/Linux , which defines the  operating system .  GNU  is the  free software  that provides open source equivalents of many common UNIX commands. The  Linux  part of this combination is the  Linux kernel , which is the core of the operating system. The kernel is loaded at boot time and stays running to manage every aspect of the functioning system. The story of Linux begins with  UNIX , an operating system developed at AT&T Bell Labs in the 1970s. UNIX is written in the  C  language making it uniquely portable amongst competing operating systems, which were typically closely tied to the hardware for which they were written. I...

  Linux is Everywhere Hello and welcome to  Information Technology HelpDesk Online ! Linux is everywhere; Linux jobs are everywhere. There is a demand for Linux skills in just about every industry and job category on the planet, and not enough Linux talent to meet this growing demand. It’s also fun and rewarding to work with something that’s so much a part of our modern lives yet which so few people understand. If someone says they have Linux experience, it might refer to configuring systems, running web servers, or any number of other services and programs that operate on top of Linux. Over time, Linux administration has evolved to encompass just about every task that a modern business, educational institution, or government organization might use in their daily operations. The journey of learning you are beginning today has no ending point. It can take you in a myriad of different directions, from cybersecurity to application and game development, system administrati...