Which layer of the linux system contains system daemons and shells?

Resolution

Summary: "This article is an overview of the Linux operating system".

Operating Systems

An operating system is the software that manages the hardware resources associated with your laptop, desktop, or server.

Another way of thinking about an operating system would to view the operating system as a translator between the software you use, and the hardware it’s installed on. Its primary role is communication between the two separate layers to create a seamless experience for the user. There are various pieces housed inside the operating system which allow the unit to function.

An operating system is the software that manages the hardware resources associated with your laptop, desktop, or server.

Operating systems are varied and include Various Linux Distributions, Windows version and the Mac OS X are available for deployment on computer systems.

Operating System (OS) Components:

• The Bootloader: This part of the software manages the way the computer boots. Most of the time this is seen by the users as the splash screen that pops up before giving way when the operating system takes over.
• The Kernel: The kernel is the most basic level of the OS. This is also the piece which also referred to as "Linux". The kernel is the core piece of an operating system and manages the CPU, memory, and peripheral devices.
• Daemons: Background services that start up on boot or once you have accessed the operating system.
• The Shell: Similar to the DOS prompt seen in Windows OS, this is the command process which enables a user to control the computer by entering commands typed into a text interface. This is housed by the terminal in Ubuntu.
• Graphical Server: The sub-system which displays graphics on your monitor.
• Desktop Environment: The part we normally interact with. This includes the built-in applications.
• Applications: Software titles that are not readily available when a basic operating system has been installed on a system. These are available for download onto a system.

So what is Linux?

Linux is a word which encompasses many variations of operating systems which were developed using a kernel created by Linus Torvalds as an open source alternative.

Open source means that anyone is freely licensed to use, copy, study, or change the software in any way. The source code, the collection of instructions which tells the computer how to act, is shared openly to encourage continued development.

Applying this Linux kernel has created a source of operating systems which do not require purchase in order to use and install.

This is countered by proprietary code, where the source code is hidden from the users and has restricted use to copy right law.

Variations of Linux: Distributions

A simple way to think of a Linux Distribution, or "distro", is envision the different variations we have of Windows. While each version of the Windows Operating system has the same core parts, each one can look vastly different as we compare version 7 to version 10.

The same can be said for distros. Each Linux distribution will house the same core components using the open source code, but each will have differences in the functionality and appearance. The use of the Linux kernel coupled with these variations create over 600 available distributions of the Linux OS.

With so many versions of Linux software available, these distros can be created to work on specific systems like desktops, laptops, netbooks, and even mobile phones.

Distros can be commercially backed such as Fedora (Red Hat), openSUSE (SUSE), and Ubuntu (Canonical Ltd.) or entirely community driven such as Debian, Slackware, Gentoo, Arch Linux.

What versions of Linux does Dell support?

Currently, Dell offers support for Ubuntu and Red Hat distributions of Linux.

Ubuntu is on the client and consumer based systems, whereas Red Hat (RHEL) is maintained on several servers in Enterprise.

Linux Definitions

• Package: In Linux a package refers to a compressed file archive which has all the files needed for a specific application. These are stored in repositories online.
• Package Manager: Handles all updates for installed software when a new update is available for download. This is also the service used for installation of new software onto a system.
• Repository: A location where a collection of software packages is stored in order to be retrieved and installed on a system.
• APT (Advanced Packaging Tool): which simplifies the process of managing packages by automatically retrieving, configuring and installing the updates.
• Shell: A scripting language which takes your command lines entered from the keyboard and executes them on the system. Bash and C shell are examples.
• Terminal: The interface used for the Shell.
• Terminal Emulator: When a terminal is accessed through the graphical user interface, GUI, it is a simulated version of the chosen shell interface.
• BASH (Bourne Again Shell): a type of shell found in Linux distributions. BASH is basically an extension of the shell scripting language used in a terminal.

Ubuntu Definitions

• Dash - The Ubuntu version of the start menu. This is brought up by clicking the dash icon on the Unity launcher.
• Unity Launcher - Files stored in your computer with a desktop extension. It will appear on the left hand side of the screen and provide you quick access to applications, workspaces, removable devices, and the trash.
• Compiz Config Settings Manager (CCSM) - Not installed in Ubuntu by default, but can be installed through the Software Center for Ubuntu. You can use this add in to change settings in Ubuntu’s Unity Desktop.
• Ubuntu Unity - Just as Windows has its desktop representation for a user interface, Ubuntu has its own variation. This is referred to as Unity.
• Variants - A good way to understand this is to refer to the various versions of Windows. Just as Windows has variations of Windows 7 that range from Home, Professional, and Enterprise, Linux distributions take on the same structure. Changes to the Ubuntu distribution are labeled as Kubuntu, Lubuntu, Ubuntu Gnome, or Edubuntu.
• Ubuntu Version Numbers - The version numbers seen with Ubuntu indicate the release date for that version of the operating system. 16.04 indicates the release date of April 2016.
• Normal Releases versus Long Term Support - There is a bit of variation when it comes to the length of time a version of the Ubuntu OS is supported and updated. LTS, long term support versions, are typically supported for two years until the next release of an updated operating system. Normal releases come out about every six months, and have the version number to indicate they are a mid-supported release, example, 16.10 was released October of 2016.

What are the layers of Linux?

What are the three main layers of the Linux operating system architecture?

What is Linux kernel layer?

Which layer of the Linux system is the core component of the operating system and responsible for managing memory processing and security?