In the previous article, we reviewed several Raspberry Pi models and considered which are most suitable depending on the application. Most of the time, you will be using RPi as a Linux computer. Raspbian, the official operating system for Raspberry Pi, is a variant of Debian OS (a Linux Distribution). Other operating systems are available, but Linux is typically preferred.
From an electronics perspective, any computing device is a digital electronic circuit that can process and execute a set of digital instructions in a programmed order so that specific tasks are completed. The programmed order of these instructions is called an application. When an operating system runs on the computing device, the Screenshot of Raspbian OS on Raspberry Piapplications, and all of the hardware resources, are managed by it.
The operating system is, therefore, a unique program designed and developed to manage hardware resources, data, memory, and applications.
Any application “allows” the hardware to manipulate the data. For example, a word processing application allows a computer:
- To read data input from a keyboard
- Display typed data or data files through a graphic user interface on the screen
- Save data files to a secondary memory device
- Print the data using a printer or plotter.
The data can be runtime data or files stored on the secondary memory device. The data files that store the application on a secondary memory device are called programs. At runtime, the programs are called processes. However, the processes cannot directly access hardware resources. They must interact with the operating system for access to the hardware resources, primary memory, other files that are on the secondary memory, or to transfer the data from one device to another.
It is the operating system that is responsible for:
- Managing and allocating hardware resources
- Allocating primary and virtual memory resources
- Manage processes
- Maintain file system
- Protect files and data on secondary storage.
The person using the computer is called the user. The user interacts with applications through the input/output peripherals. To manage the transfer of data from the input/output peripherals, device drivers must be installed on the operating system. These device drivers are programs that dictate data communication with a hardware component. Each hardware device connected in the computer system has a device driver that must be explicitly installed on the operating system to let it interact with the specific hardware device.
Additionally, the operating system is responsible for providing a user interface (command-line or graphical) to let the user access the files stored on the secondary or removable storage devices, and interact with the application programs. It also provides system services or utility services, such as the scheduling of processes, file handling, manipulation of text, printing, networking, etc. These services run as separate processes and are initiated when the operating system is booted. The application programs may need to access or interact with one or several of these services for specific tasks.
Linux operating system
Linux is an open-source operating system that was first developed by Linus Benedict Torvalds. The software is available as a Linux kernel for free without a license fee. This means anybody can download and modify the source code of Linux to have his or her own Linux distribution. The Linux Kernel is written in C programming language.
It is combined with:
- System utilities (GNU utilities)
- Shell — a special utility for a user to manage files and programs.
- Desktop environment, which adds a graphic user interface to the Linux Kernel.
- Default application software, written for the Linux Kernel, and forms a complete operating system.
Together, the Linux Kernel with its combined features, is a ready-to-use Linux distribution — and there are hundreds of Linux distributions. Interestingly, Linux is not limited to any platform, meaning its different distributions are available as an operating system for desktops, servers, mobile devices, mainframe computers, supercomputers, and embedded devices.
The current Linux desktop share is 1.74 to 2.18 percent. About 85 percent of mobile devices are running on Android, which is a Linux derivative. Approximately 66 percent of servers use Linux and almost all supercomputers run on custom Linux variants.
The Linux Kernel is periodically updated and made available for download. A version number identifies each new release, which is composed of three components:
1. The major number indicates a significant revision to the Linux Kernel.
2. The minor number refers to minor changes and stability of the version. If the minor number is odd, it means that it’s a development kernel. If it’s even, it’s a production kernel. Development kernels are not fully tested and can be unstable. A production kernel is a fully tested and stable release of Linux Kernel.
3. The revision number specifies minute changes to the kernel. For example, the latest stable Linux Kernel version is 5.4.1 (November 2019), in which 5 is the major number, 4 is the minor number, and 1 is revision number. This is a production kernel.
Linux is available under GNU Public License, which was developed by the Free Software Foundation (FSF), a nonprofit with a global mission to promote computer user freedom. Under GPL, any software and its source code must be freely available. If someone modifies the source code, it should also be redistributed without any license fee.
So, Linux is an Open Source Software (OSS). Under Open Source license, the software and source code must be available free of charge. This means software companies and developers are unable to generate revenue on an OSS because the software and its source code, must be distributed for free under the open-source licenses. As a result, OSS developers (and Linux developers) generate revenue by selling the hardware that runs an OSS, the closed-source software that runs on an OSS (such as the applications for Linux), or by providing related customer support.
As an operating system, Linux has a few notable features. It provides multi-threading, multi-tasking, and multi-user capability, as well as a stable, secure, and monolithic kernel. It also offers the versatility of the hardware platform, multiple file system options, open-source code, simple customization, and low operational costs.
Popular Linux distributions include Red Hat, Fedora, Slackware, Arch Linux, OpenSUSE, Mandriva Linux, Gentoo, Debian, Ubuntu, CentOS, PCLinuxOS, Puppy Linux, Solus, Elementary OS, etc. Raspbian is a Linux distribution that’s based on Debian.
Any Linux system has these building blocks:
- Linux Kernel
- GNU utilities
- Desktop environment
- Add-on application software
To learn more about these building blocks, check out this article: “Any Linux System at a Glance.” It’s an important read to understand the different software components that make up a Linux operating system and how they function.
In the next article, we learn how to set up a Raspberry Pi computer. Be ready to get your hands dirty from the following tutorial and onwards.