Plan 9’s filesystem is a very simple network filesystem protocol to share files between systems. They are specifically using 9P2000.L.
They considered using Samba and SMB instead but can’t rely on Samba being installed and usable in the Linux guest OS and didn’t want to ship it because Samba is GPL licensed.
They picked Plan 9 because it’s much simpler to implement. Also Microsoft already had Plan 9 server code for some other Linux container project they’d done.
The \\wsl$\ path is handled in the Windows system by the MUP, an existing hook for network-like filesystems. They added a new one for Plan 9.
The $ is in the name so that it can’t be confused with a computer whose hostname is wsl.
The Plan 9 server in Linux communicates with the Windows Plan 9 client via a Unix socket. (Windows supports Unix sockets; who knew?)
Windows can access your Linux files even if no Linux is instance is running. There’s a new Windows service called LXSManagerUser that mediates user identity and permissions.Only since Windows 10 build 17063 (December 2017 pre-release) [0] [1], which was released as Windows 10 April 2018 Update. So for the first 25+ years of Windows' existence, it didn't.
And although it does implement the basic functionality, it is missing features found on mainstream Unix-like platforms, e.g. file descriptor passing (SCM_RIGHTS)
[0] https://devblogs.microsoft.com/commandline/af_unix-comes-to-...
Same with other hypervisors, virtualbox etc do the same. If you have docker installed on macOS it also uses 9p to share data with the host.
But IMO 9p is a terrible choice for this, particularly because it doesn’t support hard links. It breaks a lot of software like sccache etc which rely on hardlinks to work.
The reply from the plan9 devs on why this is the case hits staggering levels of arrogance:
> If you look at what a hard link is, you'll realize why they are not in Plan 9.
https://groups.google.com/g/comp.os.plan9/c/24mMVoy6wXA/m/JW...
I'd even suggest it reflects humility not arrogance.
He is right however, you are also right: it's because Windows and Docker publish 9p server in a stupid way. It shouldn't be just the guest fs, you should be able to make any file server you like so hard links would be useless (as they are in plan9) because you would decide what filesystem organization layout you need.
You could make do with FUSE inside the virtualized OSes I guess.
One of the “stupid” ideas I have in my back-burner is to rewrite rio so that it works like Mac OS 7 (the platinum look with window shading), which in my mind was always a very sane and efficient way to manage windows — but time is not on my side…
I have one of my usual lists of resources for it on https://taoofmac.com/space/os/plan9 - comment here if it’s missing anything you particularly like.
This is IMO the biggest drawback. Why wouldn't any user want the software to be feature rich? In fact, looking at Plan 9, I often feel that the provided software is just a MVP.
Composable software is something I’m highly interested in. There were efforts in the 1990s to make desktop software more composable, such as COM from Windows and OpenDoc from Apple, but the desktop world is still dominated by large applications such as those that constitute Microsoft Office and the Adobe Creative Suite. It would have been a wonderful opportunity for the Linux desktop world to embrace components, but, alas, the community embraced OpenOffice, GIMP, and other large applications.
COM is everywhere on Windows, specially since Vista, as the WinDev regained the control they thought Longhorn was going to take away from them.
One of Powershell strengths is the easy access to COM, just like .NET, frameworks.
Linux could do the same with D-Bus, but alas so is the distributions wars, and hate on anything like proprietary OSes, that it only has a minor role on systemd, GNOME and KDE.
It's pleasant to use a minimalist, viable product.
9front is not the only OS I use, but it is one of my daily drivers.
I should probably make time look again in case I missed something or it's improved in the last decade.
Users want feature rich systems. Individual programs are best feature-complete, but focused on a single task and capable of cooperating with others when something out of scope is desired.
From my personal viewpoint: It's not easy to hack on large monoliths, even for senior software engineers. But if every logical piece of the monolith tries to be as small as it meaningfully could, the barriers are drastically lower.
Lastly, it's really not for general users. It's for (academic?) computer people who are dexterous and willing to try new things.
To talk about the article itself, the only reason plan 9 can achieve such a design is because it's developed and used by the same small group of people. If linux is a bazaar and BSDs are cathedrals, then 9front is a monastery's citadel. Another thing that isn't mentioned is that both linux and BSD (and pretty much anything based on posix) has a lot of third party software that would be hard to maintain along with the rest of the system, if the monks even include it to begin with. And that software could include something like jq which a lot of software depends on and would love to just assume it's there.
And really, what more does someone get from something like this over, say, having a more or less formal standard on what a true plan9 system includes and waving it in someone's face when they choose to ignore it? This is pretty much what modern unices do and it works out great in cases when it's actually important. Most people don't care what commit your system is built from as long as it works as their programs expect it to.
> ... has a lot of third party software that would be hard to maintain along with the rest of the system
This is the point that the article is trying to challenge. I think 9front proves that it's doable.
> Most people don't care what commit your system is built from as long as it works as their programs expect it to.
The former helps the later a lot. Everything is tested with each other and for a lot of functionality there is only one option.
A few years ago I thought about what it would take to implement a more conventional desktop GUI on top of Plan 9, but I’ve oscillated back and forth between wanting Plan 9 with a Mac-like desktop versus wanting a modern Lisp/Smalltalk machine (with object-oriented underpinnings instead of Plan 9’s “everything is a file” interfaces) with a Mac-like desktop.
Though I do know that it puts some strong emphasis on mouse usage, something that for someone that grew to use the keyboard a lot like me (ironically, as a graphic designer) seems to be really awkward, to say the less. Its strengths seem to be its overlaying concepts and that it intended to be "the next gen Unix" - alas it won't take over for a myriad of reasons, and some would argue Unix-es have already borrowed some of its concepts for themselves.
Of course lots of it might be skill issue.
https://web.archive.org/web/20240728004832/https://posixcafe...
> Put in another way, if someone wanted the ability to touch every line of code (in the upstream sense), they would have to be a member of some non trivial amount of communities.
On a typical distro you can just download sources and start hacking, you don't need to be member of any community.
While something like Debian might not be monorepo in the strictest sense, on a conceptual level it is very close. They still have all the sources under their control and are not dependent on anything outside. They are at full liberty to accept or reject any patches regardless of where they come from, from "upstream" or "downstream".
This idea that distros are actually independent full-featured operating systems is an idea that I think is getting forgotten way too often. Distros are (or rather can be) much more than mere repackaging of upstream software.
The illustrate how I think Plan 9 is different in this regard. A patch for 9front could include a new feature for our compilers and then also show how useful it is by using it within other parts of our code. In plan 9 you can interact fully with every component.
I would say introducing a backdoor (xz) without downstream knowing is probably the biggest "privilege" you can have on a system or distribution no?
[1] Systems Software Research is Irrelevant (2000) [PDF]:
I always have the impression the discussion stops on a gas station the middle of the road, instead of on the destination.
Otherwise we could also go back to Windows NT with POSIX subsystem, fork it to a version where the UNIX experience was first class like on NeXTSTEP and macOS, and then praise Windows NT UNIX qualities, that weren't there in first place. (Naturally ignoring the access to source code issue).
From the man page: bullshit - assemble a stream of bullshit from words in a file
It will produce output like (ran it 3 times)
persistence firewall markup realtime-java callback-scale generator
virtual polling polling SQL out-scaling blockchain
converged converged singleton property self-signing-based element polling just-in-time control