August 25, 1991, Helsinki, Finland.
A 21-year-old student posted a message on a Usenet newsgroup:
“Hello everybody out there - I’m doing a (free) operating system (just a hobby, won’t be big and professional like gnu)… I’d like to know what people think…”
He was Linus Torvalds. He had just released the first version of Linux—version 0.01.
He just wanted to make an operating system to learn about operating systems in university. He didn’t expect this “hobby project” to change the world.
Linus’s Hobby#
Linus was born in 1970 in Helsinki, Finland. He had been fascinated by computers since childhood.
In 1991, he was studying computer science at the University of Helsinki. The course required him to learn about operating systems, but the Minix operating system used by the school had limited functionality.
Linus thought: Why not write an operating system myself?
He bought a 386 computer and started writing code. He first wrote a terminal emulator, then added disk drivers, file system, process scheduling…
A few months later, he had a working operating system kernel.
He posted the code on an FTP server, inviting interested people to download and test it.
The GNU Project#
Before Linux, there was a similar project: GNU.
In 1983, Richard Stallman launched the GNU project, aiming to create a completely free operating system.
Stallman was a programmer at MIT. He believed: Software should be free—anyone should be able to use, modify, and distribute it.
GNU developed many components of an operating system: compiler (GCC), editor (Emacs), shell (Bash), libraries (glibc)… but was missing a core: the kernel.
GNU was developing a kernel called Hurd, but progress was slow.
Linux filled this gap. The Linux kernel plus GNU tools formed a complete operating system: GNU/Linux.
The Definition of Open Source#
Stallman proposed the concept of Free Software.
He defined four freedoms:
- Freedom 0: The freedom to run the program for any purpose
- Freedom 1: The freedom to study how the program works and modify it
- Freedom 2: The freedom to redistribute copies
- Freedom 3: The freedom to distribute modified versions
Note that “free” refers to freedom, not price. Stallman’s famous quote is: “Think of ‘free’ as in ‘free speech’, not as in ‘free beer’.”
In 1998, a group of developers proposed the concept of Open Source. Open Source emphasizes the development model—public source code, collaborative development—rather than philosophical ideas.
Open Source was more easily accepted by commercial companies. Today, “open source” is more widely known than “free software.”
Linux’s Development#
After Linux was released, developers began contributing code.
They fixed bugs, added drivers, ported to new hardware, and developed new features. Code was submitted through mailing lists, and Linus reviewed and merged it.
This distributed development model was very efficient. Thousands of developers collaborated, and Linux evolved rapidly.
In 1994, Linux 1.0 was released, already supporting multiple hardware architectures with fairly complete functionality.
In 1999, Linux 2.2 was released, supporting symmetric multiprocessing (SMP), able to run on multi-CPU servers.
Today, Linux is the world’s most widely used operating system kernel:
- Servers: About 96% of web servers worldwide run Linux
- Supercomputers: 100% of the world’s top 500 supercomputers run Linux
- Mobile devices: Android is based on the Linux kernel
- Embedded devices: Routers, smart TVs, car systems…
- Cloud platforms: AWS, Azure, Google Cloud all run on Linux
Linux Distributions#
The Linux kernel is just the core. To become a usable operating system, many components are needed: desktop environment, application software, package manager…
Different organizations package these components into distributions:
- Debian: Community-maintained, stable and reliable
- Ubuntu: Based on Debian, user-friendly, popular on desktops
- Red Hat Enterprise Linux (RHEL): Enterprise-grade, commercial support
- CentOS: Free version of RHEL
- Fedora: Testing ground for cutting-edge technology
- Arch Linux: Rolling release, geek favorite
Each distribution has its own characteristics and target users.
Open Source Changed Business#
Open source was initially seen as a threat by commercial companies. A Microsoft executive once called Linux a “cancer.”
But open source ultimately changed business rather than destroying it:
Red Hat: Sold Linux enterprise editions and support services, acquired by IBM for $34 billion in 2019.
Google: Open-sourced Android, becoming the mobile OS hegemon.
Facebook: Open-sourced React and PyTorch, building technical influence.
Amazon: Open-sourced various tools, contributing to the community.
Today, almost every tech company participates in open source. Open source has become the industry standard; closed source has become the exception.
The Advantages of Open Source#
Why has open source succeeded?
First, higher quality. Thousands of developers review code; bugs are more easily found and fixed. “Given enough eyeballs, all bugs are shallow.”
Second, more secure. Source code is public; security vulnerabilities are more easily discovered. Closed-source software relies on “security through obscurity”—once cracked, it’s dangerous.
Third, avoids lock-in. Using open-source software, you’re not locked into a vendor. If the vendor goes bankrupt or raises prices, you can maintain it yourself or find another vendor.
Fourth, promotes innovation. Open source lowers the barrier to innovation. Developers can stand on giants’ shoulders without starting from scratch.
Fifth, reduces costs. Open-source software is usually free, reducing software costs.
The Challenges of Open Source#
Open source also faces challenges:
Business model: How to make money from open-source software? Red Hat sells services, MongoDB sells enterprise editions, GitHub sells hosting…
Sustainability: Many open-source projects rely on volunteer maintenance, lacking funding. The Log4j vulnerability incident exposed this problem.
Governance: Who decides a project’s direction? Linus still controls the Linux kernel, but many projects lack clear governance.
Licensing: There are dozens of open-source licenses with different terms, easily causing confusion.
Linus’s Story#
Linus now works at the Linux Foundation, maintaining the Linux kernel full-time.
He still has final say over the kernel. He reviews code, resolves disputes, and decides release timing. His style is direct and frank, sometimes even sharp.
He said: “I’m just an engineer. I care about whether code is correct, not political correctness.”
Linux didn’t make him a billionaire. He didn’t start a company like Bill Gates or Steve Jobs. He gave the code to the world.
But Linux made him a legend in the tech world. He received the Turing Award (along with Japanese scientists) and was named one of Time magazine’s most influential people.
Next Step: Cloud Computing#
Linux dominates servers, but how servers are used is changing.
More and more companies are renting cloud services instead of buying servers. Amazon, Microsoft, and Google cloud platforms let anyone get computing resources on demand.
Tomorrow, we’ll discuss the cloud computing era.
Today’s Key Concepts#
Open Source Software Software with publicly available source code that anyone can view, modify, and distribute. Open source emphasizes collaborative development and open standards. Linux, Python, and Firefox are all open-source software.
Kernel The core of an operating system, managing hardware resources and scheduling program execution. Linux is a kernel, not a complete operating system. The Linux kernel plus GNU tools and other components forms a complete GNU/Linux system.
Distribution A complete operating system packaged from the Linux kernel and software packages. Ubuntu, Debian, Fedora, and RHEL are all Linux distributions, each with its own characteristics and target users.
Discussion Questions#
- Stallman said “software should be free.” Do you think software should be open source? Are there cases where it should be closed source?
- Linux became mainstream for servers and supercomputers but has only about 2% market share on desktops. Why do you think that is?
Tomorrow’s Preview: The Cloud Computing Era—how did Amazon AWS change the IT industry, making “renting servers” replace “buying servers”?