Twenty years ago, when Linus Torvalds first announced his new operating system project to a Usenet discussion group, he had no way of knowing that his creation would one day conquer the world.
"Just a hobby, [it] won't be big and professional," Torvalds wrote on Aug. 25, 1991. In a follow-up post, he added, "Simply, I'd say that porting [the OS to a different CPU] is impossible." Torvalds had begun the project as a fun way to teach himself about the Intel 80386 processor and nothing more. His greatest ambition was merely to see it work.
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It has done far better than that. Today, Linux -- as Torvalds's OS came to be called -- is available for just about every modern processor architecture and many archaic ones. It can power every kind of computing device, from PCs, netbooks, and smartphones to mainframes, supercomputing clusters, and beyond.
Linux is definitely "big and professional," having won the support of industry heavyweights such as Dell, IBM, HP, Novell, and Oracle. Red Hat, one of the first commercial Linux vendors, is now an S&P 500 company with a market capitalization of $7.3 billion.
The last 20 years haven't always been easy. Linux has made a few enemies, Microsoft foremost among them. It has faced its share of challenges, too, both technical and legal, and there are more hurdles ahead.
Nonetheless, as Linux enters its third decade, its opportunities have never been greater. Computing is changing, and Linux is not only benefiting from this change but is enabling it. Thanks to a shift beyond the PC, Linux is poised to become more than just an OS, but one of the most transformative forces in computing history -- and it's happening right under everyone's nose.
The OS the Internet built
That Linux is helping usher in a new computing age might come as a surprise to some. Linux has often been accused of following, rather than leading. Since 2003, the SCO Group has alleged that the open source OS violates intellectual property relating to Unix, and it's true that much of Linux's early market share came at the expense of costly commercial Unix variants, such as AIX, HP-UX, Solaris, and Tru64. Similarly, Microsoft has repeatedly claimed that Linux violates over 200 patents.
Linux has been innovative from its inception, however, in important ways. First, while the commercial Unix flavors ran on high-end systems based on RISC processors, Torvalds designed his OS for commodity Intel hardware, anticipating the trend toward low-cost x86 servers. Second, and even more crucial, while Microsoft was famously slow to adapt to the Internet, Linux has had the Internet at its core from the very beginning.
It's doubtful that Linux could even exist in its present form were it not for the Internet. Torvalds has played a pivotal role throughout its storied life and still personally coordinates each new kernel release -- for example, it was he who dubbed a recent stable kernel Linux 3.0, despite its having "no landmark features or incompatibilities." He's hardly alone; as one of the world's most successful open source projects, Linux represents the contributions of countless programmers worldwide. Anyone who chooses may download it, inspect it, learn from it, modify it, or use it, free of charge and with no obligation other than to allow others to do the same -- all thanks to the Internet.
Some contributors have been individuals, and many have hailed from educational institutions -- at least at the beginning. In recent years, however, the game has changed. Commercial interests are now the most prominent actors in the Linux development process. Of the top 20 contributors to the Linux 3.0 kernel, more than half were acting on behalf of their employers.
Other contributors represented prominent commercial Linux vendors, such as Canonical, Red Hat, and Suse. But arguably the most noteworthy contributors were those who represented hardware manufacturers, including Atheros, Broadcom, Intel, Marvell, and RealTek, among others. Where once component and chip set manufacturers were reluctant to assist open source developers for fear of disclosing trade secrets, today a whole range of vendors are actively contributing driver code to the Linux kernel. That's a clear testament to the project's reach and its growing importance to the overall IT industry.
Linux is everywhere
The relationship between Linux and the Internet has been mutually beneficial. Just as Linux development has benefited from the rise of the Internet, so too has the Internet prospered from Linux's evolution. Today, the open source OS is everywhere. It powers Web servers, email servers, file servers, databases, and more. In fact, according to Linux Foundation executive director Jim Zemlin, you use Linux "literally every time you surf the Internet."
For example, search engines have become the de facto home pages for most Web users. Google leads the pack with 66 percent market share, and Google's servers all run on Linux. So do most of Yahoo's, according to the Netcraft site survey. Even Microsoft Bing uses the Akamai content delivery network, which also runs on Linux. It's likely that none of these companies or their services would even exist if it weren't for the massive scalability provided by low-cost Linux servers.
Gauging Linux's share of the overall OS market, however, is an inexact science. Only public servers can be empirically measured; anything behind a firewall is a black box. Most analysts rely on sales figures from vendors and retailers. But this method ignores the many popular Linux flavors -- including CentOS, Debian, Fedora, and Ubuntu, among others -- that can be downloaded and installed for free. There is no accurate way to measure how many servers are deployed using these distros, yet informal download stats alone suggest that Linux enjoys a far greater share of the server OS market than is reflected in the commercial Linux vendors' sales figures. Given the trend toward cloud computing, its role in everyday computing is only likely to grow.
Slow growth on the desktop
Yet, as strong as Linux is in the data center, it's notoriously weak on the desktop. Some PC and netbook vendors ship systems with Linux preinstalled, but sales of these are typically low. Many pundits have pointed to Linux's failure to displace Windows as evidence that it will never succeed as a client-side OS. But are they right?
Where desktop Linux use can be measured, it seems to have found a niche among government agencies and large corporations, which typically enforce strict controls over employee desktops. Programmers also have a natural affinity for the OS, and in many cases they use Linux desktops that have been heavily customized for software development; for example, about half of all Google employees run a custom Linux variant.
It would be a mistake, however, to assume that only geeks and specialists use Linux clients. For one thing, it's equally hard to judge the number of desktop Linux installations as it is servers. Because Linux is free and runs well even on older hardware, many hobbyists deploy it themselves. Some might erase another OS to install it, while others may run it using virtualization, further confusing the numbers.
Linux gained some ground as a consumer desktop OS with the debut of Ubuntu, a free distribution that emphasizes ease-of-use and user productivity. Ubuntu is currently the most popular desktop Linux, and founder Mark Shuttleworth has said his goal is to reach 200 million users by 2015.
But that might be wishful thinking. The current figures are much more meager: According to Web analytics firm NetMarketShare, Linux desktops still represent less than 1 percent of the market. If we assume that users do most of their Web browsing from their primary PCs, then Linux doesn't have much hope of gaining traction with consumers. The trouble is, that's an increasingly misguided assumption.
Mobility and beyond
Computing is changing in dramatic ways. More and more, users of all stripes are forgoing the traditional PC desktop in favor of new types of devices, services, and usage modes. For example, in Japan, about half of all personal email is sent or received using a mobile phone, rather than a computer. That trend seems likely to carry over to the West, where smartphone use is rising sharply -- and that's a huge opportunity for Linux.
Of all the smartphones sold in the U.S. market, Android now claims the largest share of any OS, and Android is based on the Linux kernel. So are Nokia's Meego and HP/Palm's WebOS -- which, while nowhere near as successful as Android, have hardly fared worse than Windows Phone 7, though the future of WebOS remains in limbo, in light of HP's recent announcement to halt production of WebOS-based devices. In Korea, Samsung's popular Bada OS also uses the Linux kernel, as does the recently announced Aliyun in China.
What that means is that while desktop Linux use may remain low, as consumers forsake PCs for smartphones, Linux gains while desktop operating systems lose -- including Windows.
Linux powers more than just phones, too. The rise of cloud computing and SaaS has spurred demand for new classes of devices that are more lightweight than PCs yet larger and more versatile than smartphones. The market for Android tablets is growing, and they, too, run on Linux. Similarly, Google's Chromebooks, which offer a stripped-down user experience that's little more than a Web browser, rely on the Linux kernel to power their hardware.
Even devices that barely resemble traditional computing platforms are often Linux powered. Leading e-book readers from Amazon, Barnes & Noble, Kobo, and Sony are all based on the open source OS. You'll also find versions of the Linux kernel in networking equipment, GPS navigation systems, media players, TV set-top boxes, and even TVs themselves.
Many of these nontraditional devices are built using inexpensive, low-power processors based on the ARM architecture, which explains why Linux has been so successful in these markets. Robust, full-featured ports of the Linux kernel have been available for ARM since the late 1990s. By comparison, Microsoft's only ARM offering to date has been Windows CE, and it won't have a full-featured OS ready for the architecture until Windows 8 ships in 2012. As a result, Microsoft may remain the biggest threat to Linux's continued growth, even in a post-PC era.
Microsoft: Friend or foe?
Tension between Microsoft and the Linux community is certainly nothing new. In 1998, the infamous leaked "Halloween documents" established that, contrary to Microsoft's public statements, the Redmond-based giant considered open source and Linux in particular to be "a significant near-term revenue threat" to Windows.
The Halloween documents further specified various strategies Microsoft could use to attack Linux; most notably, "the effect of patents and copyright in combatting Linux remains to be investigated." Some in the Linux community have dismissed Microsoft's patent claims as mere bluster -- including Linus Torvalds himself. But in 2009, Microsoft sued navigation system vendor TomTom over patents related to Microsoft's FAT32 file system; TomTom eventually settled.
Little wonder, then, that several prominent Linux vendors and customers have opted to preemptively license patents from Microsoft rather than face the possibility of litigation, including Amazon, I-O Data, LG, Linspire, Novell, and Panasonic, among others. Recently, Microsoft signed similar agreements with manufacturers of Android-based smartphones. The net effect is that Microsoft actively profits from Linux businesses even as it works to undermine the popularity of Linux.
Yet there are signs that relations between Redmond and the Linux community are softening. One of the more surprising aspects of the Microsoft-Novell partnership was that Microsoft agreed to purchase more than $250 million worth Suse Linux licenses, which it then resold to Microsoft customers. In July, Microsoft renewed the partnership with new Suse owner Attachmate and agreed to resell another $100 million in Suse licenses.
Microsoft's strangest gesture of all, however, was its cryptic video birthday card to Linux. In it, Microsoft admitted to "trying to scare Linux off" and went on to ponder a world in which Microsoft and Linux could coexist. As olive branches go, it wasn't particularly heartwarming. But the fact that Microsoft bothered at all may be evidence that the software giant is at last coming to terms with Linux's role in modern IT -- and its place in IT's future.
The rocky road ahead
Even if Microsoft disappeared tomorrow, however, Linux would still face challenges. For starters, Microsoft is hardly the only company that could assert patents against the open source OS. In April, Bedrock Computer Technologies won a $5 million judgment against Google for patent violations related to the Linux kernel. Doubtless that was but one reason why Google sought to purchase Motorola Mobility, which has its own portfolio of more than 24,000 patents.
The rising value of the commercial Linux market may also lead to increased infighting among the Linux vendor community. For example, Oracle has frustrated Red Hat for several years by marketing what is essentially a carbon copy of Red Hat Enterprise Linux. In response, Red Hat has become more guarded about how it releases kernel code patches.
More recently, Oracle bought Ksplice, a maker of technology that allows patches to be applied to a running Linux kernel instance with zero downtime. Previously, Ksplice was available for multiple Linux distributions, including Red Hat and Ubuntu, but Oracle now says it will make the technology available for its own Linux flavor exclusively. Further actions like these could disrupt the "cooperative competition" that has characterized the commercial Linux industry to date.
Equally important, Linux's technical evolution isn't over. As successful as it has been on mobile devices so far, it could do a lot better. Linux on the ARM architecture is a morass of redundant, device-specific kernel builds and distributions, and consolidation is sorely needed.
Mobility is but one frontier for Linux to conquer. Parallel processing is another. Linux works well on today's multicore chips, but as tomorrow's chips grow to 48 cores or more, today's Linux kernel won't be able to keep up.
Between mobility and cloud computing, Linux has an unprecedented opportunity to become a dominant force the likes of which IT has never seen. But as it enters its third decade, Linux's greatest challenge may be to avoid becoming a victim of its own success. As the open source OS has matured and stabilized and its code base has grown in complexity, Linux kernel hacking is losing its allure for new developers, and recruitment may soon become a top priority if it is to overcome the hurdles ahead.
Linux's growing pains are over, but its grown-up problems have just begun. Oh, to be young again.
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This article, "Linux at 20: New challenges, new opportunities," was originally published at InfoWorld.com. Follow the latest news in software development, languages and standards, open source, and Linux at InfoWorld.com. For the latest business technology news, follow InfoWorld.com on Twitter.