I've read a lot of places that say "Plan 9 is basically a better Unix", but I'm not entirely sure why. Can someone explain what made Plan-9 special? I'm not asking in a passive aggressive sense, I genuinely want to know.
In Unix you often get stuck having to create these walled-off systems. Your editor's inner state, for instance, is not visible to other applications, so you need to come up with your own whole programming scheme. Same with your window manager. And all your networking happens through a separate set of APIs that are similar to the file descriptor APIs but different enough that nothing works transparently.
Once you have per-process mounts and a simple network filesystem, all your applications and devices can start exposing their state over that protocol. All your software and hardware are automatically networkable if you follow the design. And you can use Unix utilities to do things that previously would require whole subsystems to be built. You don't need to build your own programming language for Acme, because Acme's state is visible as a filesystem. Same with the window manager. And you don't need to build a custom networking scheme for sharing Acme with your friend on another machine, because you can export Acme's filesystem to that machine (or have your friend export their keyboard onto your machine as a child of the Acme process).
"Everything really is a file" is a good way to sum it up. But that's only possible and relatively safe because of 9P and per-process namespaces.
https://github.com/Harvey-OS/harvey
The development seems active, the last commit was made 7 hours ago.
Last time I checked the project was still in its early stages. Docs and stability have improved a lot since then.
Sidenote: I think 9P protocol and plan9 userland like ACME editor is available on linux.
I don't have a ton of cash but I believe in the hacker culture and as an aspiring developer I figure I'd put my money where my mouth is.
It would be nice, if they'd provide an ISO. The thing I noticed about Plan9 clones and Inferno is that, they almost always run entirely in the userland. I think that's the reason HarveyOS does not provide an iso. I am not sure they are building a standalone operating system.
If you're interested you could also try inferno, however getting it up and running is also a hassle.
Lastly, in the case you're not aware, Plan9 and inferno also have a very interesting history. Inferno and Java were once direct competitors. Limbo a programming languages invented for Plan9 is also mentioned in the Dan Brown's best seller Digital Fortress.
IMHO Plan9 spirit still lives in Golang, like the Lisp Machines' spirit lives in Emacs. Maybe with cloud based OS's we could see the ideas behind Plan9 in everyday world. But other than that Plan9 remains an OS for hobbyists and idealist computer folk :).
This is a property exclusive to inferno.
> Same with your window manager.
> You don't need to build your own programming language for Acme, because Acme's state is visible as a filesystem.
I don't see how it's good programming practice to expose your internal state to direct read/write access from other programs. It seems to violate basic encapsulation principles.
Your quotes are making me think of some really important takeaways from the Longhorn disaster with WinFS, detailed in a recent submission[1]:
> More profoundly, Bill’s vision of an ecosystem of applications that all store and share their data in this relational store is in direct conflict with how applications build their data models. While some desktop applications (and almost all internal IT-written ones) use relational stores for their internal data model, they do not want to expose those data models for unmonitored read and write by other applications. I detailed some of the fundamental reasons in the post referenced above, Leaky by Design.[2]
Solutions like this... "what if application state were like a relational data store, or hierarchical FS, that other programs can access", sounds great as a fun programming exercise, but it isn't often how people actually want to design applications.
[1] https://hackernoon.com/what-really-happened-with-vista-4ca7f... [2] https://hackernoon.com/leaky-by-design-7b423142ece0
Right down to the TCP/IP stack... you can run a program called "sshnet" and connect to a remote unix box, the /net in that process' namespace now has a tunnel to the remote box, and all children of that process that opt-in to share the namespace now have a VPN-like to the network you just ssh'd to.
Because the network stack is a file system you can do basic open, read, write, close stuff to dial up remote services and work with them. As such there's IRC clients written in the shell, without evil extensions like /dev/tcp in bash.
It's fun, but it doesn't outrun any other OS I've seen. Maybe that's changed.
9p is v9fs in linux. There's FUSE 9p stuff for other platforms. There's a virtualized Erlang runtime that sits directly on Xen as the OS that uses 9p. 9p is part of QEMU's way of talking to the guest (or is it the host?) OS.
It's been on a lego mindstorm brick too.
To me, kernel dbus is a bit more like mach_ports. Those have their own advantages too. As did Solaris Doors.
That kind of pervasiveness involve replacing all i/o through the entire system with dbus. File systems, netlink, sun rpc, mmap, signals and kill, tcp, and so on.
And then making dbus sanely deal with networking and authentication.
9p isn't just pervasive: it's the only way to talk to the system, which means that if you want to mess with namespacing things, all you need to think about is 9p.
So with that in mind, I would rephrase that as "Inferno is basically a better Unix".
You can learn more about it, including the programming manual with lots of Limbo examples at:
http://doc.cat-v.org/inferno/4th_edition/
You can easily see some of Go's pedigree on Limbo's design.
Nowadays Inferno is still being sold by Vita Nuova, the company that acquired the rights after Bell Labs folded the project.
https://en.wikipedia.org/wiki/Newsqueak
Alef was pretty neat too and was also on Plan 9
It really is a neat idea, and shows what can be done when you take an idea to its logical extreme. But the interface is not human friendly. Real-world workloads are complicated and require kernels that handle the weird edge cases so you can't reduce a production kernel to a simple idea. And 9p performance lags behind other networked file systems. So it's really more of a prototype and a laboratory for generating ideas to be used in other systems, rather than a replacement for production Unix.
Distributed name spaces, distributed computing, compute servers, distributed file servers and so on.
Remember the SUN slogan 'the network is the computer'? Plan 9 makes that a reality.
- Truly everything is a file. No exceptions; no special cases.
- Symlinks do not feel like a hack causing trouble. If you need a reference to a directory in another path, you mount it. If your software writes its binaries into its custom directory and you want the binaries within the $PATH, you mount that custom directory into /bin (or so, from what I remember).
- Namespace isolation for processes.
- Distributed file system
As graphics fan, I wonder how this would work out with modern GPU driver layers.
https://marc.info/?a=111558719100068&r=1&w=4
Though Rob Pike might have not been very cooperative or enthusiastic
https://marc.info/?l=9fans&m=111558699517143&w=4
He goes on about some interesting architectural advantages already in Plan 9 from a graphics programming standpoint and capitalizing on them someday.
It'd be interesting to hear about how far along he got.
https://marc.info/?l=9fans&m=111558698816997&w=4
Here he talks about trying to hack Plan 9 to run Quake https://marc.info/?l=9fans&m=111558698416915&w=4
This is seriously underappreciated IMO. You can entirely replace access control with private namespaces without any real loss in generality. In fact, they're more flexible and secure.
You see some of these ideas in Linux, but as with all Linux kernel technologies they all feel like they've not been written with a design in mind from the start (just look at epoll, namespaces, /proc, and so on).
> "Unix allows file systems to be built up from disparate resources using concepts such as links and file system mounts. These features masked the original directory; if one mounts a new filesystem on the directory named "net", one can no longer access its previous contents until the operation is reversed.
> Plan 9 introduced the idea of union directories, directories that combine resources across different media or across a network, binding transparently to other directories. For example, another computer's /bin (applications) directory can be bound to one's own, and then this directory will hold both local and remote applications and the user can access both transparently.
> Using the same system, under Plan 9 external devices and resources can be bound to /dev, allowing any device to be shared over the network without any additional code."
So, you can union mount other machines /dev/cpu/ folders into your machine's /dev/cpu folder and then have access to all the CPU's. Same for all other hardware, software and storage.
Just these two things - Union Mounts and 9P - when built into the whole system, create a very dynamic distributed computing environment. I really, really wish more of this would make it into Linux. We've kinda got some of it, but without joining up all the other bits, the real power isn't quite there.
More:
http://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs http://plan9.bell-labs.com/plan9/ http://en.wikipedia.org/wiki/9P2000 http://en.wikipedia.org/wiki/V9fs http://en.wikipedia.org/wiki/List_of_distributed_computing_p... http://en.wikipedia.org/wiki/Inferno_\(operating_system\) http://doc.cat-v.org/plan_9/4th_edition/papers/plumb http://swtch.com/plan9port/
Union mounts and 9P are already available in Linux.[1][2] What other things would you like to see?
[1] - https://lwn.net/Articles/325369/
[2] - https://www.mjmwired.net/kernel/Documentation/filesystems/9p...
C replaced by Go, as Inferno replaced it with Limbo for userpace applications.
As for your SML hint, I leave here "Unix system programming in OCaml" :)
It's also not really a central concept. plan9 doesn't have a $PATH env var, for example - you just union mount all your binaries into `/bin`.
Again, yes there's an implementation on 9p for linux - but it's not baked in and it's not used by the system as a unifying abstraction - this makes it fairly useless:
> Unlike most other operating systems, Plan 9 does not provide special application programming interfaces (such as Berkeley sockets, X resources or ioctl system calls) to access devices.
> Instead, Plan 9 device drivers implement their control interface as a file system, so that the hardware can be accessed by the ordinary file input/output operations read and write.
> Consequently, sharing the device across the network can be accomplished by mounting the corresponding directory tree to the target machine.
It's really having this stuff baked in and then combining them that gives you the power & elegance: https://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs#Combinin...