What is Linux? Commands Glossary and FAQ

What is Linux?

Linux is an open-source operating system (OS). Operating systems are programs that manage applications and support a computer’s basic functions. An OS is essential to a computer system because it’s responsible for managing hardware resources and handling all operations, including running software. After Microsoft Windows and Apple iOS versions, Linux OS versions are the primary option for users worldwide who prefer open-source software [1]. 

What is open-source software?

Software with source code that any user can view and change is open source. Nearly all open-source software is free to the public. Proprietary software (or, closed-source software) is the inverse of open-source software because it is owned by a single entity and licensed to those who want to use it. 

What is Linux used for?

Linux is a popular platform for organizations needing to host data, services, or applications securely. Its desktop environment can also be used on personal computers. Common Linux use cases include:

• Server applications. Linux is suitable for running web servers, file servers, database servers, and other shared servers that require high-volume support. 

• Software development. Linux’s open-source software development tools are popular among enterprise-level businesses. The widely used version control system Git was developed for Linux Kernel by creator Linus Torvalds. 

• Cloud computing. Linux’s open-source, highly scalable nature makes it a suitable OS for cloud infrastructure. 

• Game development. Linux can be installed on various platforms, including mobile devices and video game consoles. 

Unix vs. Linux 

Unix is a proprietary operating system for desktops, laptops, and servers. It was written in the programming language C for optimal portability and modification. While Linux is used by both organizations and individuals regardless of their technical expertise, Unix is typically used in internet servers, commercial distributions, and other large organizations such as universities. 

Read more: Unix vs. Linux Comparison Guide

Linux components

Operating systems are made up of a suite of programs that enable a computer to operate. A Linux-based operating system consists of three main parts: the kernel, shell, and programs. In the following sections, we’ll provide a brief overview of each one. 

What is a Linux kernel?

The Linux kernel is the central component of a Linux operating system, hence the name kernel. It serves as the communication interface between a computer’s hardware and processes. Linux kernels are responsible for controlling all major functions and managing computer resources such as files, processes, memory, and devices. 

What is a Linux shell?

A shell is a specialized program that enables users to execute commands and use operating system services. The Linux shell acts as a translator, translating natural-language user commands and files into input that the kernel can understand. There are two classification levels of a Linux shell:

1. Command line shell. A command line shell is accessible via a command line interface (CLI). CLIs are computer programs that rely on the direction of text-based input for task execution. Examples of command line interfaces include Terminal and Command Prompt. 

2. Graphical shell. A graphical shell is accessible via a graphical user interface (GUI). GUIs are interfaces that are designed for users to interact with by clicking, scrolling, tapping, or some other action initiation. 

What are Linux programs?

Linux programs are typically designed to do one thing efficiently. These specialized programs can be used together in many different ways. You can think of them as customization parts that enable you to add functionalities to your Linux operating system as needed. 

What is a Linux device? 

A Linux device is any piece of technology, physical or virtual, that is powered by Linux and has a specific functionality. Examples include block devices like USB sticks and character devices like keyboards. 

Linux commands

Linux commands are utilities of the Linux OS. All tasks in Linux can be accomplished by executing commands through the Linux terminal. The list below answers a few of the most frequently asked questions about Linux commands. 

Tip: Remember that Linux commands are case sensitive. 

What is cat command in Linux?

In Linux, Cat stands for concatenate. It is a commonly used, pre-installed command that can display the contents of files, link multiple files together into an output file, and adjoin content to existing files. The cat command in Linux can also be used to format file outputs. 

What is tar in Linux?

Tar is a file management command that is short for tape archive. It is used to create and extract compressed files that contain several files packaged together for portability and storage purposes. These files are also known as archive files. 

What is tarball in Linux?

Tarball in Linux refers to several files packaged together and compressed with a compression program called gzip. Tarballs can be used to move large binary files. 

What is echo in Linux?

Echo in Linux is a built-in command that is used to display the string or line of text passed as the arguments. It prints arguments to the standard output. 

What is wc in Linux?

The command wc in Linux stands for word count. It’s a utility command that calculates the word count, line count, or byte count in a file. 

What is sudo in Linux?

Sudo stands for “super user do” and it’s a command prefix that only superusers have the ability to run. Adding sudo to a command enables users with the correct permissions to execute commands as other users, similar to the Windows feature “run as administrator.” 

What is sh in Linux?

In Linux, sh is a command language interpreter. Using sh ensures that the commands read and executed from a command line string or specified file will be expressed in shell command language. 

What is export command in Linux?

The export command in Linux is a built-in utility used to create environment variables. It ensures that those environment variables and functions will be passed to child processes without affecting the existing environment variable. 

What is nc in Linux?

The nc command in Linux stands for netcat. It’s a command-line utility that enables you to read and write data between two networks. This command is especially useful for sysadmins and network administrators. 

What is xargs in Linux?

In Linux, xargs is a general command that enables users to build and execute command lines from standard input. 

Learn more about Linux with Coursera 

You can learn to use Linux with an industry leader in technology by enrolling in IBM’s Hands-on Introduction to Linux Commands and Shell Scripting. In this beginner-friendly, self-paced online course, you’ll learn how to describe Linux architecture, update and install software on a Linux system, and more in around 14 hours.