In the 1990s and well into the 2000s, if you had mission-critical applications that required zero downtime, resiliency, failover and high performance, but didn\u2019t want a mainframe, Unix was your go-to solution.\nIf your database, ERP, HR, payroll, accounting, and other line-of-business apps weren\u2019t run on a mainframe, chances are they ran on Unix systems from four dominant vendors: Sun Microsystems, HP, IBM and SGI. Each had its own flavor of Unix and its own custom RISC processor. Servers running an x86 chip were at best used for file and print or maybe low-end departmental servers.\n\nLearn more about Unix\n\n10 Unix commands every Mac and Linux user should know\nDealing with Unix arguments\n9 ways to compare files on Unix\nHow to learn Unix\/Linux\nAll you need to know about Unix environment variables\n\n\nToday it\u2019s a x86 and Linux world, with some Windows Server presence. Virtually every supercomputer on the Top 500 list runs some flavor of Linux and an x86 processor. SGI is long gone. Sun lived on for a while through Oracle, but in 2018 Oracle finally gave up. HP Enterprise only ships a few Unix servers a year, primarily as upgrades to existing customers with old systems. Only IBM is still in the game, delivering new systems and advances in its AIX operating system.\nWe aren\u2019t going to dwell on how we got here. Instead, this is a look at where commercial Unix is going, and how and when it will eventually die. (Note: We're specifically talking about the decline of commercial Unix. Still flourishing are the free and open-source variants such as FreeBSD, which was born out of the Berkeley Software Development (BSD) project at the University of California, Berkeley, and GNU.)\nUnix's slow decline\nUnix\u2019s decline is \u201cmore of an artifact of the lack of marketing appeal than it is the lack of any presence,\u201d says Joshua Greenbaum, principal analyst with Enterprise Applications Consulting. \u201cNo one markets Unix any more, it\u2019s kind of a dead term. It\u2019s still around, it\u2019s just not built around anyone\u2019s strategy for high-end innovation. There is no future, and it\u2019s not because there\u2019s anything innately wrong with it, it\u2019s just that anything innovative is going to the cloud.\u201d\n\u201cThe UNIX market is in inexorable decline,\u201d says Daniel Bowers, research director for infrastructure and operations at Gartner. \u201cOnly 1 in 85 servers deployed this year uses Solaris, HP-UX, or AIX. Most applications on Unix that can be easily ported to Linux or Windows have actually already been moved.\u201d\nMost of what remains on Unix today are customized, mission-critical workloads in fields such as financial services and healthcare. Because those apps are expensive and risky to migrate or rewrite, Bowers expects a long-tail decline in Unix that might last 20 years. \u201cAs a viable operating system, it\u2019s got at least 10 years because there\u2019s this long tail. Even 20 years from now, people will still want to run it,\u201d he says.\n Gartner\n\nGartner tracks the decline of new Unix sales.\n\n\nGartner doesn\u2019t track install base, just new sales, and the trend is down. In Q1 of 2014, Unix sales totaled $1.6 billion. By Q1 of 2018, sales were at $593 million. In terms of units, Unix sales are low, but they are almost always in the form of high-end, heavily decked-out servers that are much larger than your typical two-socket x86 server.\nIBM the last UNIX man standing\nIt\u2019s remarkable how tight-lipped people are over the state of Unix. Oracle and HPE declined to comment, as did several IBM customers. IBM is still in the game, but Bowers notes, \u201cI see IBM investing $34 billion in Red Hat, but I don\u2019t see IBM investing $34 billion in AIX.\u201d\nSteve Sibley, vice president of cognitive systems offerings at IBM, acknowledges the obvious but says IBM will still have a substantial number of clients on AIX in ten years, with the majority of clients being large Fortune 500 clients. He adds that there will also be a stable number of midrange customers in some ways \u201cbecause they don\u2019t want to spend the investment to get off AIX.\u201d\nRob McNelly, senior AIX solutions architect at Meridian IT, a services provider and heavy AIX user, says there is an 80\/20 rule for new applications for AIX: 80% of customers don\u2019t grow their AIX footprint, but 20% stays and expands in AIX.\n\u201cBecause 20% is the larger enterprise systems, it is a very big segment. In healthcare, many stable tier 1 production environments continue to invest and enjoy the stability and security of AIX. Established and embedded ERP systems do likewise at all layers,\u201d McNelly says.\nMany new applications pursue Linux, which causes some migration off of AIX, while static, non-changing environments just stay in stable AIX, he adds. "Some applications are going to Linux, but most of the low-end stuff already moved. Think of the mainframe; existing users stay because it has great value, but not many new customers are migrating to the mainframe."\nFinance, healthcare and big manufacturing are the primary industries sticking with Unix, Bowers says. Banking firms are often able to afford these big systems, while healthcare has strict regulatory requirements that pressure companies to stay put on the Unix platform.\n\u201cNo one buys a platform for the platform,\u201d McNelly says. "They buy an application. As long as application support remains for some key platforms, it's hard to beat the value of AIX on [IBM Power Systems]. Many times after companies do some analysis, [and consider] the current stability and the migration effort, [it] makes no sense to move out of something that\u2019s perfectly functional and supported and has a strong roadmap into the future.\u201d\nThe biggest complaint Bowers hears about Linux is not the OS itself but the hardware it runs on. Many Unix systems have something called hard partitioning, which is like virtual machines, but it sets up physically separated partitions on the system. Hard partitioning has multiple benefits. For example, Bowers notes that in some cases, enterprise software vendors (Oracle is one example) will give you a discount if you use hard partitioning. This is a hardware solution only Unix systems offer today.\nUnix is the new mainframe\nWhile Unix is in decline and there is only one commercial vendor left, the other two popular flavors will hang around for a while. Oracle may have ended development of Solaris but has committed to support Solaris until 2034. HP Enterprise says it will support its various HP-UX servers for five years after their obsolescence date, which varies. SGI\u2019s IRIX has been off the market and out of support since 2006.\nSibley says the trend IBM is seeing is clients less focused on moving off AIX and more focused on how to extend and migrate going forward. "The vast majority of customers are extending what they are doing with AIX and not looking to get off," he says.\nThe primary reason people move off AIX is they are worried there won\u2019t be the skills to support it in the future, because customers believe AIX is dying. "That\u2019s what gets people\u2019s attention. As long as they have confidence we will be around a long time, and we have new releases every year, then there\u2019s no reason to get off,"\u00a0Sibley says.\nSo Unix will live on at least in the form of AIX due to IBM\u2019s commitment, even as the others fade out in the coming decades. No one expects a supernova-like implosion. Just a very slow, long fade.\n\u201cUnix will never die. There is no research that is trying to come up with a new operating system to replace Unix or Linux,\u201d Greenbaum says. \u201cIt won\u2019t die the way mainframe systems have not died. They are still in use. But this stuff fades out of view because it loses strategic value.\u201d\n\u201cBy 2020, Unix will represent 3% of total server revenue, down from 8% today,\u201d Bowers says. \u201cThere\u2019s not going to be a rush for the exit. Unix will fade away."\nIn the end, Unix\u2019s greatest success likely won\u2019t be as an enterprise server but as an option for consumer products. Apple\u2019s MacOS and iOS are both derived from FreeBSD \u2013 and that installed base isn\u2019t going anywhere.