Unix operating systems rule the world. From the comfort of a Windows desktop, this may not seem like it, but when we add up the world of servers, the desktop with Linux or macOS and the world of mobile, the champion is clear and unquestionable. It may therefore come as a surprise to people unfamiliar with Plan 9 that it is an improved successor to Unix directly from its original authors, but it has never been a substitute in the full sense of the word.
Work on Plan 9 began in the early 1980s, when Bell Labs decided to take Dave Presotto, Phil Winterbottom and Rob Pike, Ken Thompson and Denis Ritchie one step further. The newly created system has been able to do things from the beginning that are not common in unix-like systems, even today Plan 9 is fully distributed, for example, so it allows running on multiple computers, which may not be the same architecture, but for users it looks like a computer. The load is distributed as needed to individual nodes, the storage can also be located in geographically separated places.
In order not to create complete chaos, everything is realized by abstraction at the file level. Simply put, in Plan 9, everything is a file, a file placed in the right place on the filesystem. Although this also applies to some extent in Unix (for example / dev), here it is without exception – the network (/ net), all communication between processes (/ proc) also has a file-level representation. Some concepts have proven to be very beneficial and have made their way into other systems (such as procfs or 9P), others have probably been too revolutionary and remain to this day only in Plan 9. Things that are not very related to concepts, but have their origin here and you are using it is UTF-8 encoding, which Ken Thompson invented and first implemented for Plan 9.
The first two versions from 1992 and 1995 were released under a proprietary license for universities and non-commercial use, the other two versions (2000 and 2002) each under a different, own open-source license from Lucent, then owner of Bell Labs. The current owner of Bell Labs is Nokia, which has decided to solve everything a little more radically.
She transferred all the rights to the Plan 9 Foundation, founded in 2009, which, as a first step, released everything under a standard MIT license. According to a press release from Nokia, it is aware of the historical benefits of the system, which it has just got rid of, but investment in further development cannot be economically justified, so it entrusts it to the community and hopes to start the next stage of its development.
Personally, I can say that of all the systems I’ve ever tried, Plan 9 is the most different. Everything there is somehow familiar, but it usually works completely differently than you would expect. Talking about some market penetration is practically irrelevant, as the only operating system will be used by a maximum of hundreds of individuals worldwide – otherwise it is mainly a system for researching new ways and methods. However, this is becoming much more popular for greatly improved successors.
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