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I'm still confused. What is Nix? Is it an OS, or a package manager? From the looks of it it's a package manager that I should be able to use it on any POSIX sys

I'm still confused. What is Nix? Is it an OS, or a package manager? From the looks of it it's a package manager that I should be able to use it on any POSIX system, but I doubt that's the case?

yjftsjthsd-h 6y ago
> From the looks of it it's a package manager that I should be able to use it on any POSIX system, but I doubt that's the case? No, that's basically true. It's fully supported on Linux and Darwin, assorted BSD support is underdeveloped but in scope.
statenjason 6y ago
What is Nix? Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. It provides atomic upgrades and rollbacks, side-by-side installation of multiple versions of a package, multi-user package management and easy setup of build environments. What is NixOS? NixOS is a Linux distribution with a unique approach to package and configuration management. Built on top of the Nix package manager, it is completely declarative, makes upgrading systems reliable, and has many other advantages. [1]: https://nixos.org/ https://nixos.org/
- mehrdadn 6y ago
  Thanks, but that makes me wonder how that's even possible given that distros make their own modifications? Do people port each distro's packages to Nix then? Are they kept up-to-date? Or does it automatically translate from apt/pacman/etc. databases somehow? Or does it just basically install vanilla packages on all distro?
  - throwaway894345 6y ago
    Yeah, there is a giant repo of package definitions at https://github.com/NixOS/nixpkgs https://github.com/NixOS/nixpkgs. Those definitions tell nix how to build everything from the ground up.
  - tathougies 6y ago
    > how that's even possible given that distros make their own modifications? Own modifications to what? All the packages in nixpkgs depend only on other packages in nixpkgs. If you install nix on an ubuntu system and then install a package from nixpkgs, then that package won't use any ubuntu libraries.
    - mehrdadn 6y ago
      > Own modifications to what? To the packages. e.g. I believe Ubuntu modifies Python so that sudo pip install uses /usr/local instead of /usr. Lots of other patches and backports I'm not necessarily aware of. That's basically what makes Ubuntu Ubuntu, otherwise it'd be more like Arch. So how does Nix deal with this? Do you get the value-add from your distro or do you basically end up with pseudo-Arch wherever you start?
      - fwip 6y ago
        If you install python through nix, you get the nix version. If you install python through apt, you get the ubuntu version.
        mehrdadn 6y ago
        I get that part. I'm asking what the Nix version is like. Is it like the Ubuntu version with all the patches and backports and everything, or is it like the Arch (i.e. basically original unmodified) version?
        catern 6y ago
        Nix packages are typically close to upstream, but low-level packages sometimes have patches to make them more reproducible and deterministic, so that they work better with Nix's efforts for determinism and purely-functional packaging. Nix packages are created from scratch, not copied from another distro. Nix is typically one of the most up-to-date distros: https://repology.org/ https://repology.org/
  - l3s2d 6y ago
    Not a Nix user, but my understanding is that it's a standalone package manager with its own repositories. On a non-Nix distro, installing a package with Nix is akin to installing a Python module with pip, instead of the distro's package manager. It would not be managed at all by the distro's package manager. On NixOS, Nix is the distro's package manager.
    - mehrdadn 6y ago
      Thanks, but I already got that much. It doesn't answer my question though. If Ubuntu has made a modification to a package (that's basically the entire point of most distros, otherwise they'd be Arch), should I expect those changes in whatever Nix installs? It also leaves so many other questions unanswered, like what happens if I install GRUB or a new kernel or something else that's supposed to modify the system globally... but that's secondary.
      - solarkraft 6y ago
        NixOS only has nixpkgs modifications, not Ubuntu's, as much as Fedora doesn't have Ubuntu's modifications. My understanding is that packages available for Nix are patched to work within its context, but otherwise kept as original as possible, with optional configuration switches.
      - catern 6y ago
        No, you should not expect Ubuntu's modifications in packages installed through Nix. Things like GRUB or the kernel version are handled at the level of NixOS, because, as you say, they affect the system globally.
      - Fnoord 6y ago
        The documentation [1] mentions the possible configuration flags for a package, including Grub (which is not the default bootloader, btw). [1] https://nixos.org/learn.html https://nixos.org/learn.html
      - ymse 6y ago
        Nix packages can not modify the system globally, by design. Not even on NixOS. This is why Nix allows unprivileged users to install anything. When you install a package with Nix, all you are doing is drop a symlink in your ~/.nix-profile pointing to some /nix/store/<unique-identifier> item. When you build a package with Nix (also does not require root privileges), it happens inside a container that can only write to /nix/store/<unique-identifier>. The <unique-identifier> is a cryptographic hash based on all the inputs (dependencies) to the package (also /nix/store/<hash> items) as well as the build script.
leadingthenet 6y ago
It’s a package manager that underlies NixOS. It can also be run under any other Linux distro, and macOS.
- X6S1x6Okd1st 6y ago
  And of course Windows Subsystem for Linux
kdtsh 6y ago
Nix is a package manager. NixOS is an OS which includes the Nix package manager. My understanding is that a feature of Nix is you can declare an OS (I.e. declare the collection of configurations and software etc for an OS) which Nix will process to provide you with an OS called NixOS.
- prox 6y ago
  So it processes the config file (and thus all needed packages) one time or does it process it every time you boot?
  - heisenzombie 6y ago
    You type nixos-rebuild switch and it builds you an entire OS and drops you into it. It also makes the new OS the default on startup. Because it's all purely declarative, your old OS is still there. If things go wrong then you can just pop back to it, either in the command line with: nixos-rebuild switch --rollback Or when you reboot, the previous 'generations' of your operating system show up in GRUB, so just choose an older one to boot.
    - prox 6y ago
      Thanksfor your comment.This is very interesting for my Raspberry Pi. The ability kit it out according to function is great.
  - takeda 6y ago
    Whenever you run `nixos-rebuild switch` a symlink is created for `/run/current-system` which is the current system. That's what is used on every boot until another change (you also have an option in boot loader to boot into prior versions (it is just a symlink))
pjkundert 6y ago
POSIX (eg. Linux), Mac and Windows. Yes, it is magnificent. Immutable, deterministic software on all 3 major platforms. Combined with cached build artifacts, builds and their outputs (including complete target system updates/upgrades) are blisteringly fast, cryptographically secure and completely deterministic. EDIT: Sorry, yes; Windows only via WSL, not natively on Windows proper.
- mehrdadn 6y ago
  Windows? You're kidding me! Where do I see Windows support? On their website I only see Mac and Linux.
  - exdsq 6y ago
    You can use it on WSL1 and WSL2 but you can't use it natively on Windows. I used it on WSL2 just this afternoon and it was seamless but that makes sense because WSL2 is basically just a Linux VM anyway.
    - _hl_ 6y ago
      Although I don't see why it wouldn't work on Windows natively. Sure, it would probably need a complete reimplementation to replace all the POSIX stuff with Windows stuff, but fundamentally it ought to be possible?
      - exdsq 6y ago
        Sure in theory but there are a few open bugs: https://github.com/NixOS/nix/issues/2651 https://github.com/NixOS/nix/issues/2651 https://github.com/NixOS/nix/issues/2292 https://github.com/NixOS/nix/issues/2292 https://github.com/NixOS/nix/issues/1203 https://github.com/NixOS/nix/issues/1203 There's a locking issue with SQLite and the Sandbox has some namespace issues where Linux and Windows behave differently. I don't know how eager they are to make it work on Windows either, but at least WSL works :)
      - matthewbauer 6y ago
lmickh 6y ago
It is pretty easy to be confused. Especially since it is also a language yet all the other replies at the time have writing have failed to mention that. While I like the project as a whole, their naming is horrible. Just wait until you get into `nix-env` vs `nix-shell` etc...
- mehrdadn 6y ago
  Thanks, yeah. Conceptually I'm having a hard time wrapping my head around it since package managers are so tightly tied to an OS... I feel like surely I can't just use it in place of (say) apt or pacman without causing problems? And I haven't even gotten to the language/shell/etc. as you mention...
  - lmickh 6y ago
    You use the language to define the configuration, packages, and etc. NixOS isn't so much an OS configured by a package manager as much as it is an OS + package manager that you can configure with the Nix language. Then there is also lot of tooling to hid all of the symlink magic. It is very deep rabbit hole. Most of the quick touch examples will basically look like magic.
  - solarkraft 6y ago
    You're right that using 2 traditional package managers in the same environment will cause problems almost immediately, since both will want to control the same resources. This is less so with Nix, as it mostly operates on its own folder called nix-store, the binaries in which are then symbolically linked to. It is actually designed to be able to be used this way. I know people are using it on Mac OS and I intend to install more and more packages through it to later possibly transition to NixOS.
  - saurik 6y ago
    Package managers are not tied to the OS. Essentially your fundamental misunderstanding here, from reading your comments, is that you are expecting a package manager on Ubuntu to manage "Ubuntu's packages", when the packages belong to a repository as accessed by a package manager, and "Ubuntu" doesn't really exist: "Ubuntu bionic" is merely "a bunch of deb packages that you can install from a particular repository using apt", while "CentOS 7" is merely "a bunch of rpm packages that you can install from a particular repository using yum". You can add Ubuntu eoan or even Debian stretch repositories to your APT configuration on Ubuntu bionic, and install those packages... now, the naming and compatibility of dependencies might be different as you get further and further from what you were "supposed" to be using, but they will download and install (at worst an installation script will be missing a dependency and the package will be left "half installed", which is a technical APT term). You can also install rpm on Ubuntu: it is even in the Ubuntu bionic repository. Now, what happens if you install an rpm file using it? It might very well overwrite something from a package you installed by apt, and neither might notice that happened. But you can do it. You can install yum (this will require manual install as I don't think yum is available from any common Ubuntu repositories) and then give it a CentOS 7 repository and install all the packages and what you will be left with will be approximately CentOS 7 (with some detritus from Ubuntu). So on any system apt is managing deb packages and yum is managing rpm packages and where those packages come from is just some configuration, so you can install apt on CentOS 7 and use it to install packages from Debian stretch. You can't use apt on CentOS to manage CentOS packages as apt doesn't do that (though maybe you could teach it an "rpm method" or something but rpm's version numbering and dependency management aren't really the same so this is now just a confusing digression to avoid "technically you could" responses: yes, but then you are coding that yourself). The only real exception to all of this is the kernel, but not even always as the kernel is kind of a file, but the way it is configured in the master boot record could be different... but like, you might have some distribution local kernel patches that their tools rely on for some reason, and upgrading libc on a running system is fraught with peril even when you aren't doing something insane this, so like: don't do this, but know it works. I routinely thereby create a little folder on a Debian/Ubuntu box in which I can chroot to install a little world of an entirely different set of packages from a different package manager maintained by a different vendor as provided for some random specific version of their distribution. (Alternatively, rpm supports an argument to set the system root.) In that world there are no conflicts, as you made a folder for it. When you install packages from apt or yum, usually they assume they could go in /. That is going to maximize conflicts unless you do the chroot. Nix has chosen to package their stuff not like that, and so you can install their packages on any other environment without it conflicting or overwriting. So no, you don't "use it in place of apt" to manage Ubuntu packages, but maybe Nic and Ubuntu have chosen to both package the same thing you want (this is hopefully common as both are hopefully quite complete) and so you might "use it in place of apt" because you don't want to install an Ubuntu package, you want to install a Nix package instead. And as Nix packages go to special folders automatically, it doesn't damage your Ubuntu install.
exdsq 6y ago
One really cool thing about NixOS is you declare the OS just like you might a DockerFile, and you can choose which configuration file you use at booting time. This lets you install applications just during up-time (to try out a new tool), add it to the configuration file if you like it, and roll back to the version before if it breaks something. Versions are declarative too (PSql == X.X.X) and upgrades/downgrades are set there too. If I want to share an environment with someone I can just share the configuration file minus the secrets.
- enriquto 6y ago
  > One really cool thing about NixOS is you declare the OS just like you might a DockerFile, But DockerFiles have a really terse, self-evident, trivial to read language. It is obvious what a given DockerFile means even if it's the first one you see. For nix; well, I have seen a few nix files and each one leaves me more confused than the last. Can anybody point me to good examples of beautiful, single-file, complete, self-contained terse nix examples that describe a few simple systems? Everything that I seem to find are small fragments of stuff.
  - throwaway894345 6y ago
    This is because Nix needs to express a lot more so builds are reproducible and incremental. Docker doesn’t care about these things.
    - enriquto 6y ago
      Even if Docker doesn't really care about this, the DockerFiles themselves can also describe a reproducible process, and they are certainly "incremental" due to caching (not sure of what you mean by "incremental"). Does nix power merit such a big compromise against simplicity and readability?
      - progval 6y ago
        Because Dockerfiles delegate all the complexity to a package manager (apt, apk, ...), which has its own languages (eg. debian/rules for apt). Using Docker without any package manager doing this job would be a completely different story. And btw, you can also use Nix to build docker images. For example, here is what would be the equivalent of a Dockerfile but with Nix: https://nixos.org/nixpkgs/manual/#ex-dockerTools-buildImage https://nixos.org/nixpkgs/manual/#ex-dockerTools-buildImage > the DockerFiles themselves can also describe a reproducible process It's trickier. You need to pin all versions of all packages you use, even indirect dependencies.
deleted 6y ago
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tel 6y ago
It's kind of a mess. Nix is a collection of tools and systems that together form a highly reproducible build system. Nix is also a declarative, largely pure and lazy programming language that you use to design and specify the different build outputs for the Nix build system. Nixpkgs is, more or less, the only project written using Nix (and a lot of shell). It's a collection of many thousands of "derivations", many of the things you'd expect to be able to fetch from brew or apt. Each derivation encodes the steps to use Nix (the build system) to construct that output. NixOS is a Linux distribution built atop Nix, Nix, and Nixpkgs. The basic claim to fame here is "totally declarative system setup" where you write all of the configuration for your system in Nix, using Nixpkgs and some other NixOS specific tooling and libraries, and then "build" the entire system with high repeatability. Then there are a few other related projects such as Hydra (a CI server and binary cache builder—most of the time you don't build with Nix, just download the proper thing from the cache) and NixOps (an extension to NixOS which provisions whole fleets of servers declaratively). Finally, you don't need to run NixOS in order to benefit from Nix. Nix and Nixpkgs are (largely) compatible with MacOS and Linux. That means you can install Nix onto your existing MacOS or Linux system and use it a lot like you'd use brew or apt. That said, the premiere Nix experience is always NixOS.
- mehrdadn 6y ago
  Thanks! So let's say I start installing Nix packages. What distro's packages would they end up most similar to? Say, maybe Arch (which mostly leaves things unmodified)? Does that mean you basically end up with Arch no matter which distro you're on?
  - catern 6y ago
    Trying to put it politely, but your question seems a bit confused. Arch is not the only distro that strives for minimal modifications on upstream packages. In fact, most distributions work that way - it's Debian and its derivatives that's the outlier, and these days, even Debian rarely patches upstream packages. There is much more to distributions than what patches they apply to their packages. The package manger they use, their default configurations, their compiler toolchain, their C library, their init system, their stance on software freedom, etc etc - much more than just what patches they apply to their packages. But, yes, Nix packages are mostly close to upstream, with occasional patches to improve determinism and reproducibility.
gnulinux 6y ago
> From the looks of it it's a package manager that I should be able to use it on any POSIX system, but I doubt that's the case? That's exactly the case. It works by installing apps per user and not globally, so they're put into your home directory.
mossity 6y ago
I started reading this thinking Nix was a programming language, became very confused when it started talking about files and an object database.
- bb010g 6y ago
  Smalltalk has object databases, as images.
choward 6y ago
> What is Nix? It's everything you could ever ask for and more. On a more serious note, I get the question though. This article isn't very compelling. NixOS is a linux distribution that allows you to specify your system in a declarative way. This means instead of running imperative bash commands like "apt-get git". You declare that you want git installed with something like environment.systemPackages = [ git ... ]; This may not sound that interesting you but it makes your system reproducible. So you have some plain text files that describe you entire system. You can check these into git or whatever. If you reinstall and use the same configuration as before you will be back at the same state so it makes no sense to do a reinstall of the entire OS. If you want to upgrade NixOS versions it doesn't really make sense to do a complete reinstall also. Rollbacks are also built in in case you make a mistake you can quickly go back. Your previous "generations" are shown in the boot menu if you restart your computer. NixOS also can run virtualized environments like docker, vms, etc. With docker it can be used run docker containers and startup. It also has it's own concept of containers which can be thought of like docker containers except they run NixOS so you specify them the exact same way as any other NixOS configuration. Unlike docker, it allows you to share packages between containers and the host system while also having isolation. Nix packages are packages like in most other package managers. It's also relatively easy to create your own packages. You can use NixOS configuration to install packages or use it on it's own as a non-root user to install nix packages while on other OSes to for example replace homebrew on Mac OSX. It also allows you to install multiple versions of the same package. You can also us it build docker images so you don't actually need a Dockerfile and you can install the docker images which get saved to the nix store. You manage them just like another package. That's right, this means you can both build and run docker images without actually using docker. NixOps is a tool for deploying NixOS to multiple computers. It builds everything on the host and copies it to the nodes. If two of your nodes use the same package it's only downloaded once. This means no configuring an apt-cache or something like that if you don't want all your machines downloading their own copies of everything. It also allows you to provision and deploy to the cloud. It basically replaces terraform, cloudformation, etc. Nix is the language used to configure NixOS and NixOps as well as to create packages that can be installed. Nix files themselves don't do anything. They just build a configuration object. You can almost thing of them as glorified JSON generators that generate the configuration which the respective nix tool uses to get whatever job done it needs to. Now don't get me wrong, the learning curve is very steep but once you learn it you "get it" and realize how it all ties together and it starts to make perfect sense. I left a lot out here (like development) but It basically solves every need I have programming, infrastructure, and computers in general and I won't go back to anything else.
aaronjanse 6y ago
Nix is a package builder & manager that creates reproducible build environments. Using the Nix language, you specify what the build environment should look like ($PATH, what should be in the build folder, etc). Nix then calls a program of your choice to do the actual building. Just like Nix lets you specify a build environment using the Nix language, NixOS lets you specify, using the Nix language, what you want your operating system to look like (systemd services, $PATH, etc). You should be able to use Nix, the package builder & manager, on any POSIX system afaik.
takeda 6y ago
Nix really is a purely functional, lazily evaluated language that is great at expressing dependencies in your project. You can think of it as a make on steroids, but it is much more than that. Because the language expresses what to build from a known state (i.e. nothing is installed) together with its purely functional properties, means that for the same input (source code, dependencies, configuration options, system architecture etc) it supposed to always generate the same output. Nix can be think of as package manager, and its nix-env command (which BTW is discouraged from Nix purist to use[1]) behaves like a package manager, but IMO it's more of a build system. After the author of Nix wrote his thesis he mentioned that the language can describe an entire operating system. That's how NixOS happened. You can have a single configuration file that describes what needs to be installed on your OS how configured etc. The great thing is that you can take such configuration file, and recreate another machine with it configured exactly as you want it. No need for chef/salt/ansible etc. It actually has an edge over these tools, for example if you tell that specific package needs to to be installed, and than later you remove the package from the config, nix will remove that package as well (with chef/salt/ansible, you would need to add a state that's uninstalling the package), another benefit is that all changes are atomic, you either have your changes applied or nothing is changed, there's nothing in between (this makes things like replacing X11 with Wayland, or KDE with Gnome just another change, that you can always revert). It's a very powerful tool, and the more I use the more amazing it seems. It shows that if you target specific problems the right way a lot of common headaches are eliminated. [1] it's advisable to never install packages by hand using nix-env, since that adds mutability to your system, instead you should use nix-shell (another great tool) to temporarily make specific application available, use the global configuration.nix to install packages globally on the system, or use home-manager extension which allows you to configure each home directory (that means what dot files do, but also each user can have their individual packages, and goes further, for example you can even control what extensions firefox should have installed)
- bb010g 6y ago
  home-manager is wonderful. I haven't used nix-env in years.
Gaelan 6y ago
Nix is a package manager, and nixpkgs is its "official package respositry." Both of those pieces should work on any (decently popular) POSIX system. NixOS is a Linux distribution that uses Nix in place of apt or yum or what-have-you, and uses nix to allow the entire system to be configured declaatively.

I'm still confused. What is Nix? Is it an OS, or a package manager? From the looks of it it's a package manager that I should be able to use it on any POSIX system, but I doubt that's the case?

yjftsjthsd-h 6y ago

> From the looks of it it's a package manager that I should be able to use it on any POSIX system, but I doubt that's the case? No, that's basically true. It's fully supported on Linux and Darwin, assorted BSD support is underdeveloped but in scope.

statenjason 6y ago

What is Nix? Nix is a powerful package manager for Linux and other Unix systems that makes package management reliable and reproducible. It provides atomic upgrades and rollbacks, side-by-side installation of multiple versions of a package, multi-user package management and easy setup of build environments. What is NixOS? NixOS is a Linux distribution with a unique approach to package and configuration management. Built on top of the Nix package manager, it is completely declarative, makes upgrading systems reliable, and has many other advantages. [1]: https://nixos.org/ https://nixos.org/

mehrdadn 6y ago
Thanks, but that makes me wonder how that's even possible given that distros make their own modifications? Do people port each distro's packages to Nix then? Are they kept up-to-date? Or does it automatically translate from apt/pacman/etc. databases somehow? Or does it just basically install vanilla packages on all distro?
- throwaway894345 6y ago
  Yeah, there is a giant repo of package definitions at https://github.com/NixOS/nixpkgs https://github.com/NixOS/nixpkgs. Those definitions tell nix how to build everything from the ground up.
- tathougies 6y ago
  > how that's even possible given that distros make their own modifications? Own modifications to what? All the packages in nixpkgs depend only on other packages in nixpkgs. If you install nix on an ubuntu system and then install a package from nixpkgs, then that package won't use any ubuntu libraries.
  - mehrdadn 6y ago
    > Own modifications to what? To the packages. e.g. I believe Ubuntu modifies Python so that sudo pip install uses /usr/local instead of /usr. Lots of other patches and backports I'm not necessarily aware of. That's basically what makes Ubuntu Ubuntu, otherwise it'd be more like Arch. So how does Nix deal with this? Do you get the value-add from your distro or do you basically end up with pseudo-Arch wherever you start?
    - fwip 6y ago
      If you install python through nix, you get the nix version. If you install python through apt, you get the ubuntu version.
      - mehrdadn 6y ago
        I get that part. I'm asking what the Nix version is like. Is it like the Ubuntu version with all the patches and backports and everything, or is it like the Arch (i.e. basically original unmodified) version?
        catern 6y ago
        Nix packages are typically close to upstream, but low-level packages sometimes have patches to make them more reproducible and deterministic, so that they work better with Nix's efforts for determinism and purely-functional packaging. Nix packages are created from scratch, not copied from another distro. Nix is typically one of the most up-to-date distros: https://repology.org/ https://repology.org/
- l3s2d 6y ago
  Not a Nix user, but my understanding is that it's a standalone package manager with its own repositories. On a non-Nix distro, installing a package with Nix is akin to installing a Python module with pip, instead of the distro's package manager. It would not be managed at all by the distro's package manager. On NixOS, Nix is the distro's package manager.
  - mehrdadn 6y ago
    Thanks, but I already got that much. It doesn't answer my question though. If Ubuntu has made a modification to a package (that's basically the entire point of most distros, otherwise they'd be Arch), should I expect those changes in whatever Nix installs? It also leaves so many other questions unanswered, like what happens if I install GRUB or a new kernel or something else that's supposed to modify the system globally... but that's secondary.
    - solarkraft 6y ago
      NixOS only has nixpkgs modifications, not Ubuntu's, as much as Fedora doesn't have Ubuntu's modifications. My understanding is that packages available for Nix are patched to work within its context, but otherwise kept as original as possible, with optional configuration switches.
    - catern 6y ago
      No, you should not expect Ubuntu's modifications in packages installed through Nix. Things like GRUB or the kernel version are handled at the level of NixOS, because, as you say, they affect the system globally.
    - Fnoord 6y ago
      The documentation [1] mentions the possible configuration flags for a package, including Grub (which is not the default bootloader, btw). [1] https://nixos.org/learn.html https://nixos.org/learn.html
    - ymse 6y ago
      Nix packages can not modify the system globally, by design. Not even on NixOS. This is why Nix allows unprivileged users to install anything. When you install a package with Nix, all you are doing is drop a symlink in your ~/.nix-profile pointing to some /nix/store/<unique-identifier> item. When you build a package with Nix (also does not require root privileges), it happens inside a container that can only write to /nix/store/<unique-identifier>. The <unique-identifier> is a cryptographic hash based on all the inputs (dependencies) to the package (also /nix/store/<hash> items) as well as the build script.

leadingthenet 6y ago

It’s a package manager that underlies NixOS. It can also be run under any other Linux distro, and macOS.

X6S1x6Okd1st 6y ago
And of course Windows Subsystem for Linux

kdtsh 6y ago

Nix is a package manager. NixOS is an OS which includes the Nix package manager. My understanding is that a feature of Nix is you can declare an OS (I.e. declare the collection of configurations and software etc for an OS) which Nix will process to provide you with an OS called NixOS.

prox 6y ago
So it processes the config file (and thus all needed packages) one time or does it process it every time you boot?
- heisenzombie 6y ago
  You type nixos-rebuild switch and it builds you an entire OS and drops you into it. It also makes the new OS the default on startup. Because it's all purely declarative, your old OS is still there. If things go wrong then you can just pop back to it, either in the command line with: nixos-rebuild switch --rollback Or when you reboot, the previous 'generations' of your operating system show up in GRUB, so just choose an older one to boot.
  - prox 6y ago
    Thanksfor your comment.This is very interesting for my Raspberry Pi. The ability kit it out according to function is great.
- takeda 6y ago
  Whenever you run `nixos-rebuild switch` a symlink is created for `/run/current-system` which is the current system. That's what is used on every boot until another change (you also have an option in boot loader to boot into prior versions (it is just a symlink))

pjkundert 6y ago

POSIX (eg. Linux), Mac and Windows. Yes, it is magnificent. Immutable, deterministic software on all 3 major platforms. Combined with cached build artifacts, builds and their outputs (including complete target system updates/upgrades) are blisteringly fast, cryptographically secure and completely deterministic. EDIT: Sorry, yes; Windows only via WSL, not natively on Windows proper.

mehrdadn 6y ago
Windows? You're kidding me! Where do I see Windows support? On their website I only see Mac and Linux.
- exdsq 6y ago
  You can use it on WSL1 and WSL2 but you can't use it natively on Windows. I used it on WSL2 just this afternoon and it was seamless but that makes sense because WSL2 is basically just a Linux VM anyway.
  - _hl_ 6y ago
    Although I don't see why it wouldn't work on Windows natively. Sure, it would probably need a complete reimplementation to replace all the POSIX stuff with Windows stuff, but fundamentally it ought to be possible?
    - exdsq 6y ago
      Sure in theory but there are a few open bugs: https://github.com/NixOS/nix/issues/2651 https://github.com/NixOS/nix/issues/2651 https://github.com/NixOS/nix/issues/2292 https://github.com/NixOS/nix/issues/2292 https://github.com/NixOS/nix/issues/1203 https://github.com/NixOS/nix/issues/1203 There's a locking issue with SQLite and the Sandbox has some namespace issues where Linux and Windows behave differently. I don't know how eager they are to make it work on Windows either, but at least WSL works :)
    - matthewbauer 6y ago

lmickh 6y ago

It is pretty easy to be confused. Especially since it is also a language yet all the other replies at the time have writing have failed to mention that. While I like the project as a whole, their naming is horrible. Just wait until you get into `nix-env` vs `nix-shell` etc...

mehrdadn 6y ago
Thanks, yeah. Conceptually I'm having a hard time wrapping my head around it since package managers are so tightly tied to an OS... I feel like surely I can't just use it in place of (say) apt or pacman without causing problems? And I haven't even gotten to the language/shell/etc. as you mention...
- lmickh 6y ago
  You use the language to define the configuration, packages, and etc. NixOS isn't so much an OS configured by a package manager as much as it is an OS + package manager that you can configure with the Nix language. Then there is also lot of tooling to hid all of the symlink magic. It is very deep rabbit hole. Most of the quick touch examples will basically look like magic.
- solarkraft 6y ago
  You're right that using 2 traditional package managers in the same environment will cause problems almost immediately, since both will want to control the same resources. This is less so with Nix, as it mostly operates on its own folder called nix-store, the binaries in which are then symbolically linked to. It is actually designed to be able to be used this way. I know people are using it on Mac OS and I intend to install more and more packages through it to later possibly transition to NixOS.
- saurik 6y ago
  Package managers are not tied to the OS. Essentially your fundamental misunderstanding here, from reading your comments, is that you are expecting a package manager on Ubuntu to manage "Ubuntu's packages", when the packages belong to a repository as accessed by a package manager, and "Ubuntu" doesn't really exist: "Ubuntu bionic" is merely "a bunch of deb packages that you can install from a particular repository using apt", while "CentOS 7" is merely "a bunch of rpm packages that you can install from a particular repository using yum". You can add Ubuntu eoan or even Debian stretch repositories to your APT configuration on Ubuntu bionic, and install those packages... now, the naming and compatibility of dependencies might be different as you get further and further from what you were "supposed" to be using, but they will download and install (at worst an installation script will be missing a dependency and the package will be left "half installed", which is a technical APT term). You can also install rpm on Ubuntu: it is even in the Ubuntu bionic repository. Now, what happens if you install an rpm file using it? It might very well overwrite something from a package you installed by apt, and neither might notice that happened. But you can do it. You can install yum (this will require manual install as I don't think yum is available from any common Ubuntu repositories) and then give it a CentOS 7 repository and install all the packages and what you will be left with will be approximately CentOS 7 (with some detritus from Ubuntu). So on any system apt is managing deb packages and yum is managing rpm packages and where those packages come from is just some configuration, so you can install apt on CentOS 7 and use it to install packages from Debian stretch. You can't use apt on CentOS to manage CentOS packages as apt doesn't do that (though maybe you could teach it an "rpm method" or something but rpm's version numbering and dependency management aren't really the same so this is now just a confusing digression to avoid "technically you could" responses: yes, but then you are coding that yourself). The only real exception to all of this is the kernel, but not even always as the kernel is kind of a file, but the way it is configured in the master boot record could be different... but like, you might have some distribution local kernel patches that their tools rely on for some reason, and upgrading libc on a running system is fraught with peril even when you aren't doing something insane this, so like: don't do this, but know it works. I routinely thereby create a little folder on a Debian/Ubuntu box in which I can chroot to install a little world of an entirely different set of packages from a different package manager maintained by a different vendor as provided for some random specific version of their distribution. (Alternatively, rpm supports an argument to set the system root.) In that world there are no conflicts, as you made a folder for it. When you install packages from apt or yum, usually they assume they could go in /. That is going to maximize conflicts unless you do the chroot. Nix has chosen to package their stuff not like that, and so you can install their packages on any other environment without it conflicting or overwriting. So no, you don't "use it in place of apt" to manage Ubuntu packages, but maybe Nic and Ubuntu have chosen to both package the same thing you want (this is hopefully common as both are hopefully quite complete) and so you might "use it in place of apt" because you don't want to install an Ubuntu package, you want to install a Nix package instead. And as Nix packages go to special folders automatically, it doesn't damage your Ubuntu install.

exdsq 6y ago

One really cool thing about NixOS is you declare the OS just like you might a DockerFile, and you can choose which configuration file you use at booting time. This lets you install applications just during up-time (to try out a new tool), add it to the configuration file if you like it, and roll back to the version before if it breaks something. Versions are declarative too (PSql == X.X.X) and upgrades/downgrades are set there too. If I want to share an environment with someone I can just share the configuration file minus the secrets.

enriquto 6y ago
> One really cool thing about NixOS is you declare the OS just like you might a DockerFile, But DockerFiles have a really terse, self-evident, trivial to read language. It is obvious what a given DockerFile means even if it's the first one you see. For nix; well, I have seen a few nix files and each one leaves me more confused than the last. Can anybody point me to good examples of beautiful, single-file, complete, self-contained terse nix examples that describe a few simple systems? Everything that I seem to find are small fragments of stuff.
- throwaway894345 6y ago
  This is because Nix needs to express a lot more so builds are reproducible and incremental. Docker doesn’t care about these things.
  - enriquto 6y ago
    Even if Docker doesn't really care about this, the DockerFiles themselves can also describe a reproducible process, and they are certainly "incremental" due to caching (not sure of what you mean by "incremental"). Does nix power merit such a big compromise against simplicity and readability?
    - progval 6y ago
      Because Dockerfiles delegate all the complexity to a package manager (apt, apk, ...), which has its own languages (eg. debian/rules for apt). Using Docker without any package manager doing this job would be a completely different story. And btw, you can also use Nix to build docker images. For example, here is what would be the equivalent of a Dockerfile but with Nix: https://nixos.org/nixpkgs/manual/#ex-dockerTools-buildImage https://nixos.org/nixpkgs/manual/#ex-dockerTools-buildImage > the DockerFiles themselves can also describe a reproducible process It's trickier. You need to pin all versions of all packages you use, even indirect dependencies.

deleted 6y ago

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tel 6y ago

It's kind of a mess. Nix is a collection of tools and systems that together form a highly reproducible build system. Nix is also a declarative, largely pure and lazy programming language that you use to design and specify the different build outputs for the Nix build system. Nixpkgs is, more or less, the only project written using Nix (and a lot of shell). It's a collection of many thousands of "derivations", many of the things you'd expect to be able to fetch from brew or apt. Each derivation encodes the steps to use Nix (the build system) to construct that output. NixOS is a Linux distribution built atop Nix, Nix, and Nixpkgs. The basic claim to fame here is "totally declarative system setup" where you write all of the configuration for your system in Nix, using Nixpkgs and some other NixOS specific tooling and libraries, and then "build" the entire system with high repeatability. Then there are a few other related projects such as Hydra (a CI server and binary cache builder—most of the time you don't build with Nix, just download the proper thing from the cache) and NixOps (an extension to NixOS which provisions whole fleets of servers declaratively). Finally, you don't need to run NixOS in order to benefit from Nix. Nix and Nixpkgs are (largely) compatible with MacOS and Linux. That means you can install Nix onto your existing MacOS or Linux system and use it a lot like you'd use brew or apt. That said, the premiere Nix experience is always NixOS.

mehrdadn 6y ago
Thanks! So let's say I start installing Nix packages. What distro's packages would they end up most similar to? Say, maybe Arch (which mostly leaves things unmodified)? Does that mean you basically end up with Arch no matter which distro you're on?
- catern 6y ago
  Trying to put it politely, but your question seems a bit confused. Arch is not the only distro that strives for minimal modifications on upstream packages. In fact, most distributions work that way - it's Debian and its derivatives that's the outlier, and these days, even Debian rarely patches upstream packages. There is much more to distributions than what patches they apply to their packages. The package manger they use, their default configurations, their compiler toolchain, their C library, their init system, their stance on software freedom, etc etc - much more than just what patches they apply to their packages. But, yes, Nix packages are mostly close to upstream, with occasional patches to improve determinism and reproducibility.

gnulinux 6y ago

> From the looks of it it's a package manager that I should be able to use it on any POSIX system, but I doubt that's the case? That's exactly the case. It works by installing apps per user and not globally, so they're put into your home directory.

mossity 6y ago

I started reading this thinking Nix was a programming language, became very confused when it started talking about files and an object database.

bb010g 6y ago
Smalltalk has object databases, as images.

choward 6y ago

> What is Nix? It's everything you could ever ask for and more. On a more serious note, I get the question though. This article isn't very compelling. NixOS is a linux distribution that allows you to specify your system in a declarative way. This means instead of running imperative bash commands like "apt-get git". You declare that you want git installed with something like environment.systemPackages = [ git ... ]; This may not sound that interesting you but it makes your system reproducible. So you have some plain text files that describe you entire system. You can check these into git or whatever. If you reinstall and use the same configuration as before you will be back at the same state so it makes no sense to do a reinstall of the entire OS. If you want to upgrade NixOS versions it doesn't really make sense to do a complete reinstall also. Rollbacks are also built in in case you make a mistake you can quickly go back. Your previous "generations" are shown in the boot menu if you restart your computer. NixOS also can run virtualized environments like docker, vms, etc. With docker it can be used run docker containers and startup. It also has it's own concept of containers which can be thought of like docker containers except they run NixOS so you specify them the exact same way as any other NixOS configuration. Unlike docker, it allows you to share packages between containers and the host system while also having isolation. Nix packages are packages like in most other package managers. It's also relatively easy to create your own packages. You can use NixOS configuration to install packages or use it on it's own as a non-root user to install nix packages while on other OSes to for example replace homebrew on Mac OSX. It also allows you to install multiple versions of the same package. You can also us it build docker images so you don't actually need a Dockerfile and you can install the docker images which get saved to the nix store. You manage them just like another package. That's right, this means you can both build and run docker images without actually using docker. NixOps is a tool for deploying NixOS to multiple computers. It builds everything on the host and copies it to the nodes. If two of your nodes use the same package it's only downloaded once. This means no configuring an apt-cache or something like that if you don't want all your machines downloading their own copies of everything. It also allows you to provision and deploy to the cloud. It basically replaces terraform, cloudformation, etc. Nix is the language used to configure NixOS and NixOps as well as to create packages that can be installed. Nix files themselves don't do anything. They just build a configuration object. You can almost thing of them as glorified JSON generators that generate the configuration which the respective nix tool uses to get whatever job done it needs to. Now don't get me wrong, the learning curve is very steep but once you learn it you "get it" and realize how it all ties together and it starts to make perfect sense. I left a lot out here (like development) but It basically solves every need I have programming, infrastructure, and computers in general and I won't go back to anything else.

aaronjanse 6y ago

Nix is a package builder & manager that creates reproducible build environments. Using the Nix language, you specify what the build environment should look like ($PATH, what should be in the build folder, etc). Nix then calls a program of your choice to do the actual building. Just like Nix lets you specify a build environment using the Nix language, NixOS lets you specify, using the Nix language, what you want your operating system to look like (systemd services, $PATH, etc). You should be able to use Nix, the package builder & manager, on any POSIX system afaik.

takeda 6y ago

Nix really is a purely functional, lazily evaluated language that is great at expressing dependencies in your project. You can think of it as a make on steroids, but it is much more than that. Because the language expresses what to build from a known state (i.e. nothing is installed) together with its purely functional properties, means that for the same input (source code, dependencies, configuration options, system architecture etc) it supposed to always generate the same output. Nix can be think of as package manager, and its nix-env command (which BTW is discouraged from Nix purist to use[1]) behaves like a package manager, but IMO it's more of a build system. After the author of Nix wrote his thesis he mentioned that the language can describe an entire operating system. That's how NixOS happened. You can have a single configuration file that describes what needs to be installed on your OS how configured etc. The great thing is that you can take such configuration file, and recreate another machine with it configured exactly as you want it. No need for chef/salt/ansible etc. It actually has an edge over these tools, for example if you tell that specific package needs to to be installed, and than later you remove the package from the config, nix will remove that package as well (with chef/salt/ansible, you would need to add a state that's uninstalling the package), another benefit is that all changes are atomic, you either have your changes applied or nothing is changed, there's nothing in between (this makes things like replacing X11 with Wayland, or KDE with Gnome just another change, that you can always revert). It's a very powerful tool, and the more I use the more amazing it seems. It shows that if you target specific problems the right way a lot of common headaches are eliminated. [1] it's advisable to never install packages by hand using nix-env, since that adds mutability to your system, instead you should use nix-shell (another great tool) to temporarily make specific application available, use the global configuration.nix to install packages globally on the system, or use home-manager extension which allows you to configure each home directory (that means what dot files do, but also each user can have their individual packages, and goes further, for example you can even control what extensions firefox should have installed)

bb010g 6y ago
home-manager is wonderful. I haven't used nix-env in years.

Gaelan 6y ago

Nix is a package manager, and nixpkgs is its "official package respositry." Both of those pieces should work on any (decently popular) POSIX system. NixOS is a Linux distribution that uses Nix in place of apt or yum or what-have-you, and uses nix to allow the entire system to be configured declaatively.