Let’s start with GNU/Linux and its importance today. First, we call it GNU/Linux because Linux is just a Kernel which controls the memory, resources, drivers, etc. GNU stands for “GNU’S Not Unix.” GNU was a project created by Richard Stallman in 1983. The goal was to create a free Unix-compatible operating system that users could study, modify, and redistribute. From it came the GNU C Compiler (GCC), the GNU C Library (glibc), the Bash shell, core command-line utilities like (ls, cp, rm, cat, etc) along with development tools and libraries. These commands allow us to interact with the Linux Kernel, so the two married are GNU/Linux.
Linux runs much of the internet. Most web servers, cloud platforms and online services run Linux. Companies such as Amazon, Google, Meta, and Microsoft rely heavily on Linux in their data centers. When you visit a website, to include this one, chances are Linux is involved.
Linux powers the cloud. Most virtual machines and containers in the cloud environment run Linux. Technologies like Docker and Kubernetes were built around Linux features. Without Linux, modern cloud computing would look much different.
Linux dominates supercomputing. Virtually all of the world’s fastest supercomputers run Linux. Researchers use it for weather forecasting, physics simulations, medical research, artificial intelligence, and more.
Linux is also the foundation of Android. The operating system on most smartphones is based on the Linux Kernel. Every Android device contains Linux at its core.
Linux drives embedded systems such as: Routers, Smart TVs, Network appliances, Industrial controllers, Automotive systems, Internet-of-Things devices. Many people are using Linux without realizing it.
Linux fuels modern Open Source Development like Apache Software Foundation, Mozilla Foundation Projects, Kubernetes, The FreeBSD Project collaborations all benefited from the broader open-source culture that grew alongside Linux.
Linux changed the economics of computing because before Linux, organizations often had to buy expensive proprietary Unix systems, which we’ll get into. Linux gave businesses, universities, government, and hobbyists access to a Unix-like environment at little or no software cost. This drastically lowered the barrier to learning operating systems, networking, and software development.
Historically, Unix introduced many of the ideas that define modern operating systems, Linux’s importance is that it make those Unix concepts available to everyone on inexpensive hardware and eventually became the standard platform for servers, cloud computing, embedded devices, and much of modern infrastructure.
Unix taught the industry how modern operating systems should work. Linux made those ideas available to the world at scale.
Now Unix is a full operating system whereas it didn’t need to be pieced together like Linux with a Kernel and the GNU tools. Unix was created in 1969 at Bell Labs by Ken Thompson, Dennis Richie, and others. Unix introduced: Multi-user computing, Multitasking (doing multiple jobs or threads), Hierarchical file systems, Device-independent I/O (input and output), and small programs that were connected through pipes “|”.
ls -l /usr/bin | lessHere the “ls” list command with the “-l” option will list the contents of the /usr/bin directory, and if the contents are very long the “less” command will introduce pagination for easier readability.
Unix was written in C which allowed for portability. A problem back then is previous machines used Assembly Language which is difficult to program in. Each program would have to be rewritten for each different computer and its hardware. Now with C, they can compile the program for each computer that you wish to run the program.
With Unix programmers learned C, Shell scripting, Operating system concepts, and networking. Now at this point you might be saying, “Did Linux steal these commands?” Well, that brings us to what happened with Unix and how Linux came about.
A professor John Lions wrote a book that describes the code line by line what the Unix operating system did. Exactly how Unix worked, and this was taught to computer science majors across the world. The heads of Unix AT&T found out about John’s book, and they said no more teaching. When Unix version 7 came out there was a teaching ban in the license. From this point computer science students could only learn the theory of an operating system which left them with a lopsided understanding of how to implement an operating system.
This brings us to a professor named Andrew S. Tanenbaum. He wanted to teach operating systems and write a book like John Lions. Tanenbaum wrote his own operating system, and he called it MINIX. Tanenbaum was testing MINIX on a bare metal intel machine, but after an hour MINIX would crash. Tanenbaum wrote a virtual machine that would be used to run MINIX, and MINIX ran successfully. A student of Tanenbaum mentioned that there was a thermal sensor that would throw an interrupt 15, thus shutting the computer down to prevent damage. Tanenbaum could not find this in the Intel documentation. Tanenbaum being frustrated and almost giving up on his project put a piece of code in to check for interrupt 15. Sure enough after running MINIX for a while Tanenbaum got a message, “This is interrupt 15. You should not see be because I don’t exist.”
After this MINIX finally worked, which brings us to Linux. Tanenbaum wanted to keep MINIX small for teaching, and one of his students Linus Torvalds wanted more. They were working and sharing ideas on a news group, which led to Linus growing Linux. He only had a working Kernel but with GNU Tools being around, at the time, he was able to marry the two into a working operating system.
Now, it’s worth mentioning that MINIX is a micro kernel while Linux and Unix are monolithic Kernels. The difference, in short, is that in a monolithic kernel all the device drivers are included in the kernel which gives them superpower, and this can result in security issues. Most of the kernel is comprised of drivers, and drivers potentially insecure. Most programmers are interested in memory management and/or the scheduler. Drivers are rarely worked on after published, nor tested well in some cases.
In MINIX, an audio driver, for example, cannot write to the disk nor spawn processes without the Kernel’s approval. This back and forth causes latency, so most large operating systems do not use it. However, micro kernels are in CPU chips and the like.
So we can see if Andrew S. Tanenbaum gave up on MINIX, the landscape would look different today.
I hope you enjoyed this article as much as I did writing it. I will include the link to Andrew S. Tanenbaum: The Impact of MINIX