Nearly three decades ago, Linus Torvalds sent the email announcing Linux, a free operating system that was "just a hobby" and not "big and professional like GNU." It's fair to say that Linux has had an enormous influence on technology and the world in general in the 28 years since Torvalds announced it. Most people already know the "origin story" of Linux, though. Here's 28 things about Linux (the kernel and larger ecosystem) you may not already know. 

1 - Linux isn't very useful alone, so folks took to creating Linux distributions to bundle user software with it, make it usable and easier to install. One of the first Linux distributions was Softlanding Linux System (SLS), first released in 1992 and using the .96p4 Linux kernel. 

You could buy it on 5.25" or 3.5" floppies, or CD-ROM if you were high-tech. If you wanted a GUI, you needed at least 8MB of RAM. 

Note: SLS was originally incorrectly listed as the first distribution. The first was a pair of boot floppies by HJ Lu, and then MCC Interim Linux. We regret the error.

2 -  SLS didn't last, but it influenced Slackware Linux, which was first released in 1993 and is still under development today. Slackware is the oldest surviving Linux distribution and celebrated its 26th birthday on July 17th this year. 

3 - Linux has the largest install base of any general purpose operating system. It powers everything from all 500 of the Top 500 Supercomputers to Android phones, Chromebooks, and all manner of embedded devices and things like the Kindle eBook readers and smart televisions. (Also the laptop used to write this post.)

4 - When Linus announced Linux, he didn't actually announce Linux. It was not yet named, he just said "a free operating system" and that it resembled Minix. Somewhat. Later the name for Linux was going to be "Freax," a combination of "free," "freak," and "x." Ponder the name "Red Hat Enterprise Freax" for a moment, and give thanks that was averted. 

5 - Once it had a name, then people had to figure out how to pronounce it. Linus himself provided a sound file pronouncing Linux, and it's pronounced (roughly) Leenucks

6 - It's put on a bit of weight since 1991. The first Linux release weighed in less than 1MB in size, uncompressed. The most recent stable kernel (5.2.7 as of this writing) weighs in at about 103MB compressed, 946MB uncompressed. To be fair, it does a lot more now than it did in 1991.

7 - Linux wasn't initially licensed under the GNU General Public License (GPL). The first release included language about not allowing redistribution for a fee. The first version licensed under the GPLv2 was 0.99 in December 1992. Note that this is GPLv2 only.

8 - You may notice that there's a lot of choice when it comes to Linux. A lot of choice. According to the site Distrowatch, there have been more than 850 Linux distributions registered with the site. Many of which have fallen by the wayside over the years. 

The site currently lists 260 "active" Linux distributions, which of course includes Red Hat Enterprise Linux, Fedora Linux, CentOS and many others. If you were to count variants of the main distributions, like Fedora's Spins, the numbers would climb substantially. 

At one point there was even a Hannah Montana themed Linux distribution. No, we're not making that up. The world is a weird place.

9 - If you've been using Linux a while, you may remember seeing a display about "Bogomips" when a system is booting. Bogomips are a measurement of "the number of million times per second a processor can do absolutely nothing.''

Sounds silly, right? It is, but they're also useful. Linux needed a timing loop calibrated to the speed of the machine it's running on, so BogoMips were created. But it's not really useful for much else, so the name is a portmanteau of Millions of Instructions per Second (MIPS) and Bogus. These days most systems include graphical boot screens and don't display the Bogomips at all. Which is just as well, as the only reason Bogomips are preserved today is to avoid breaking userspace - some user programs apparently depend on it

If you're curious, you can find your systems Bogomips by running `cat /proc/cpuinfo | grep bog`. Each core for your CPU will have a Bogomips number. 

10 - When you boot up your computer, Linux isn't the first thing that runs. It depends on a bootloader to kick things off and then hand things over to the operating system to load device drivers and take over operation. Things were not always as simple as using a USB stick or CD-ROM to boot the system you wanted to run Linux on, either.

Linux has had a succession of bootloaders over the years, and things have come a long way in starting Linux systems. The venerable Loadlin,  bootloader would run from within MS-DOS and replace the running system to start up Linux. The first releases of SLS Linux required a boot floppy each reboot, or you could try to configure LILO by hand.

Over the years we've used LILO, BootX (for Macs), yaboot (also Macs), the SYSLINUX family of bootloaders (including bootloaders for booting from ISO images, or over the network using the PXE protocol), and the GNU Grand Unified Bootloader (GRUB) versions 1 and 2, and a number of others. 

11 -  The Linux kernel used to have a versioning system of even numbered releases for stable kernels, and odd numbered releases for development kernels. For example, the 2.2 Linux kernel series was a "stable" kernel series, 2.3 was unstable. That changed with the 2.6 kernel, when they began trying to release new kernels faster and stopped with long development cycles. 

It took about three years for the Linux kernel to reach 1.0, and then a bit more than two years to reach 2.0. It took 15 years before the kernel was versioned to 3.0, and less than five before a 4.0 kernel was released. The version number jumps aren't terribly significant at this point, Linus says "I wouldn't read too much into the number."

12 - Linux wasn't originally written to be portable. Linus targeted the 386 and that was it. The first "official" port was to DEC Alpha CPUs in 1995. The Linux kernel now runs on a large number of CPUs, though support for the 386 itself was dropped in 2012.

13 - Linux has thousands of contributors. In 2016 the Linux Foundation identified 13,594 contributors between 2005 and 2016, and counted more than 22 million lines of code in the kernel. That doesn't take into account the contributors before tracking began in 2005. 

14 - Most Linux enthusiasts have heard of the kernel's official mascot, Tux. What many folks don't know is that Tux had an official break during the 2.6.29 kernel cycle and was replaced by Tuz.

TuzTuz was a Tasmanian Devil, or Tux wearing a Tasmanian Devil costume, and was chosen to raise awareness about the species' endangered status. This coincided with the Linux.conf.au conference in 2009. Conference attendees received a stuffed Tuz plush figure and the traditional Linux.conf.au charity auction raised about AU$40,000 for the campaign to save the Tasmanian Devil. (Image by by Andrew McGown and Josh Bush. Image is licensed CC BY-SA.)

15 - One of the first, if not the first, successful worms targeting Linux reared its head in January 2001. The Ramen Worm targeted wu-ftpd, nfs-utils, and lprng and served as a heads up that as Linux gained popularity it was going to see its share of attempts to create worms, viruses, and other exploits specifically against Linux.

16 - The New York Stock Exchange (NYSE) converted to using Linux for mission-critical systems in 2007

17 - Without Linux there'd probably be no Git, either. Linus Torvalds created Git to use for development of the Linux kernel, because he wasn't happy with existing version control systems. So, Linux isn't just responsible for a huge ecosystem around the operating system, it also has laid at the heart of what's currently the most popular social development platform in use today. 

18 - Once upon a time, Apple sponsored a project to run Linux on the Mach microkernel, on top of Apple's Power Macintosh platforms. It seems to have been Apple's first foray into open source, officially, ahead of Darwin which was announced in 1999

Known as MkLinux, the first release was developed by Apple and The Open Group Research Institute in France. It was announced at the 1996 World Wide Developer's Conference (WWDC), but never caught on. By 1998 it was a community led effort and remained a niche effort in the larger Linux ecosystem.

19 - Before Google existed, finding things on the Internet was a bit more of a challenge. In 1998 a few enterprising Linux enthusiasts put together a "Linux Search Engine" to help users find information on Linux distributions, Linux User Groups, and other things Linux-related. Sadly, the contents of the search engine (more accurately, a directory) have been lost to the mists of time and bitrot.

20 - Android has brought Linux to millions of people's phones, but it wasn't the first phone to ship with the Linux kernel. That distinction, arguably, belongs to Motorola's A760 handset that was introduced in 2003 with a video player, music player, instant messaging, and other goodies. 

21 - The first commercial Android set to ship was the HTC Dream, in September 2008. That handset came with a physical keyboard, tiny trackball, and a whopping 320x480 resolution. Smartphones have improved a great deal in the 11 years or so since, but some of us still miss the physical keyboard. 

22 - The first public Red Hat release was available on Halloween, 1994. It was a beta (0.9) release and came with the 1.0.9 stable Linux kernel, or the 1.1.54 dev kernel if you felt adventurous. (And, let's face it, if you were using Linux in 1994 you were adventurous!) 

23 - Linux has branched out a lot since its inception, as we've already discussed. It's used for a dizzying array of workloads, from powering consumer devices like e-readers to AI/ML workloads on massive clusters. But did you know that there's a Linux orchestra? 

The Linux Laptop Orchestra (L2Ork) is a take on a "laptop orchestra" by Virginia Tech's Digital Interactive Sound & Intermedia Studio (DISIS). L2Ork is described as a "contemporary intermedia ensemble" that "mixes traditional orchestra with increasingly accessible human-computer interaction technologies for the purpose of exploring expressive power of gesture, communal interaction, discipline-agnostic environment, and the multidimensionality of arts." 

If that leaves you scratching your head, you can see a video about L2Ork on YouTube and enjoy the soothing sounds of Linux. 

24 - If orchestras aren't your thing, you can get a little more pastoral with Linux. Literally.

One of the unexpected workloads for Linux over the years has been… milking cows. The DeLaval "Voluntary Milking System" (VMS) lets cows decide when they'll be milked and manages the process without human intervention. All of that managed by a single-board computer (SBC) running Linux. 

25 - If you like lightweight and affordable laptops, you may want to give a little bit of thanks to Linux. The introduction of the Asus Eee PC is arguably a motivating factor in bringing costs down and introducing a focus on lighter and more portable machines. 

The Eee PC was a lightweight, smaller form factor, and cheap (less than $300 USD) "netbook" introduced in 2007. The first models had smaller than average keyboards, too, so good luck typing on them if you had larger than standard sized hands. Importantly, the Eee PC shipped with a custom Linux distribution, which meant it didn't carry a per-unit cost for the operating system itself. 

The netbook was ultimately edged out by tablets, smartphones, and devices like the Chromebook. But it was a fun experiment made possible by Linux.

26 - Installing Linux hasn't always been easy. But it is occasionally entertaining.  Back when disks were slow and installers asked a lot of questions, the Caldera OpenLinux installer featured a Tetris-type game you could play while it was copied to your drive. 

Sadly, Red Hat Enterprise Linux's Anaconda installer does not feature Tetris or any other games. It's just as well, since installing Linux on modern hardware is generally much faster than the old days of CD-ROMs and slow hard drives.

27 - It's common knowledge that Linux is used a lot in film production these days. If you're seeing a movie with a lot of CGI, there's a good chance that the rendering for that movie was done on Linux. The first major movie to use Linux, at least publicly, was Titanic. Digital Domain used a network of 200 Alpha machines running Red Hat Linux to speed up rendering times. 

28 - The Linux kernel is not released on a set schedule, so if you needed to predict when the next kernel release would drop, how would you do it? How about a crystal ball? 

Based on the "PHB Crystal Ball" website, average development time for the kernel is 68 days, and 13 days for the merge window. According to the site, the next kernel should be out on Sunday, 19 September 2019.

Happy 28th, Linux!

The history of Linux is full of fascinating facts and stories, so this is just a tiny glimpse into that history. The best, as they say, is yet to come. As interesting and impressive as Linux's past has been, its future looks equally interesting. Happy birthday, Linux and here's to many, many more!

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