NixOS: Difference between revisions

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[https://nixos.org/ NixOS] is a Linux distribution based on the [[Nix ~~Package Manager~~]]. It supports reproducible and declarative system-wide configuration management as well as atomic upgrades and rollbacks, although it can additionally support imperative package and user management. In NixOS, all components of the distribution — including the kernel, installed packages and system configuration files — are built by [[~~Nix Package Manager|~~Nix]] from [[Wikipedia:Pure function|purely functions]] called [[Nix Expression Language|Nix expressions]].

[https://nixos.org/ NixOS] is a Linux distribution based on the [[Nix]] package manager and build system. It supports reproducible and declarative system-wide configuration management as well as atomic upgrades and rollbacks, although it can additionally support imperative package and user management. In NixOS, all components of the distribution — including the kernel, installed packages and system configuration files — are built by [[Nix]] from [[Wikipedia:Pure function|purely functions]] called [[Nix Expression Language|Nix expressions]].

Since Nix uses binary caching, this provides a unique compromise between the binary-oriented approach used by distributions such as Debian and the source-oriented approach used by distributions such as Gentoo. Binaries can be used for standard components, and custom-built packages and modules can be used automatically when a prebuilt binary is not available.

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==== User Environments ====

In addition to declarative system configuration, NixOS users can utilize Nix's imperative <code>nix-env</code> command to install packages at the user level, without changing the system state. See the [[Nix ~~Package Manager~~#User Environments| user environments section of the Nix article]] for more information.

In addition to declarative system configuration, NixOS users can utilize Nix's imperative <code>nix-env</code> command to install packages at the user level, without changing the system state. See the [[Nix#User Environments| user environments section of the Nix article]] for more information.

==== Channels ====

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The main difference between NixOS and other Linux distributions is that NixOS does not follow the [https://en.wikipedia.org/wiki/Linux_Standard_Base Linux Standard Base] file system structure. On LSB-compliant systems software is stored under <code>/{,usr}/{bin,lib,share}</code> and configuration is generally stored in <code>/etc</code>. Software binaries are available in the user environment if they are placed in one of the LSB's <code>/bin</code> directories. When a program references dynamic libraries it will search for the required libraries in the LSB folders (<code>/lib</code>, <code>/usr/lib</code>).

In NixOS however <code>/lib</code> and <code>/usr/lib</code> do not exist. Instead all system libraries, binaries, kernels, firmware and configuration files are placed in the [[Nix ~~Package Manager~~#Nix store|Nix store]]. The files and directories in <code>/nix/store</code> are named by hashes of the information describing the built data. All of the files and directories placed in the Nix store are immutable. <code>/bin</code> and <code>/usr/bin</code> are almost absent: they contain only <code>/bin/sh</code> and <code>/usr/bin/env</code> respectively, to provide minimal compatibility with existing scripts using shebang lines. User-level environments are implemented using a large number of symbolic links to all required packages and auxiliary files. These environments are called [[Nix ~~Package Manager~~#Profiles|profiles]] and are stored in <code>/nix/var/nix/profiles</code>, each user having their own profiles. Structuring the system in this way is how NixOS obtains its key advantages over conventional Linux distributions, such as atomicity and rollback support.

In NixOS however <code>/lib</code> and <code>/usr/lib</code> do not exist. Instead all system libraries, binaries, kernels, firmware and configuration files are placed in the [[Nix#Nix store|Nix store]]. The files and directories in <code>/nix/store</code> are named by hashes of the information describing the built data. All of the files and directories placed in the Nix store are immutable. <code>/bin</code> and <code>/usr/bin</code> are almost absent: they contain only <code>/bin/sh</code> and <code>/usr/bin/env</code> respectively, to provide minimal compatibility with existing scripts using shebang lines. User-level environments are implemented using a large number of symbolic links to all required packages and auxiliary files. These environments are called [[Nix#Profiles|profiles]] and are stored in <code>/nix/var/nix/profiles</code>, each user having their own profiles. Structuring the system in this way is how NixOS obtains its key advantages over conventional Linux distributions, such as atomicity and rollback support.

=== Usage of the Nix store ===

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-[https://nixos.org/ NixOS] is a Linux distribution based on the [[Nix Package Manager]]. It supports reproducible and declarative system-wide configuration management as well as atomic upgrades and rollbacks, although it can additionally support imperative package and user management. In NixOS, all components of the distribution &mdash; including the kernel, installed packages and system configuration files &mdash; are built by [[Nix Package Manager|Nix]] from [[Wikipedia:Pure function|purely functions]] called [[Nix Expression Language|Nix expressions]].
+[https://nixos.org/ NixOS] is a Linux distribution based on the [[Nix]] package manager and build system. It supports reproducible and declarative system-wide configuration management as well as atomic upgrades and rollbacks, although it can additionally support imperative package and user management. In NixOS, all components of the distribution &mdash; including the kernel, installed packages and system configuration files &mdash; are built by [[Nix]] from [[Wikipedia:Pure function|purely functions]] called [[Nix Expression Language|Nix expressions]].
 Since Nix uses binary caching, this provides a unique compromise between the binary-oriented approach used by distributions such as Debian and the source-oriented approach used by distributions such as Gentoo. Binaries can be used for standard components, and custom-built packages and modules can be used automatically when a prebuilt binary is not available.
@@ Line 94: / Line 94: @@
 ====  User Environments ====
-In addition to declarative system configuration, NixOS users can utilize Nix's imperative <code>nix-env</code> command to install packages at the user level, without changing the system state. See the [[Nix Package Manager#User Environments| user environments section of the Nix article]] for more information.
+In addition to declarative system configuration, NixOS users can utilize Nix's imperative <code>nix-env</code> command to install packages at the user level, without changing the system state. See the [[Nix#User Environments| user environments section of the Nix article]] for more information.
 ==== Channels ====
@@ Line 134: / Line 134: @@
 The main difference between NixOS and other Linux distributions is that NixOS does not follow the [https://en.wikipedia.org/wiki/Linux_Standard_Base Linux Standard Base] file system structure. On LSB-compliant systems software is stored under <code>/{,usr}/{bin,lib,share}</code> and configuration is generally stored in <code>/etc</code>. Software binaries are available in the user environment if they are placed in one of the LSB's <code>/bin</code> directories. When a program references dynamic libraries it will search for the required libraries in the LSB folders (<code>/lib</code>, <code>/usr/lib</code>).
-In NixOS however <code>/lib</code> and <code>/usr/lib</code> do not exist. Instead all system libraries, binaries, kernels, firmware and configuration files are placed in the [[Nix Package Manager#Nix store|Nix store]]. The files and directories in <code>/nix/store</code> are named by hashes of the information describing the built data. All of the files and directories placed in the Nix store are immutable. <code>/bin</code> and <code>/usr/bin</code> are almost absent: they contain only <code>/bin/sh</code> and <code>/usr/bin/env</code> respectively, to provide minimal compatibility with existing scripts using shebang lines. User-level environments are implemented using a large number of symbolic links to all required packages and auxiliary files. These environments are called [[Nix Package Manager#Profiles|profiles]] and are stored in <code>/nix/var/nix/profiles</code>, each user having their own profiles. Structuring the system in this way is how NixOS obtains its key advantages over conventional Linux distributions, such as atomicity and rollback support.
+In NixOS however <code>/lib</code> and <code>/usr/lib</code> do not exist. Instead all system libraries, binaries, kernels, firmware and configuration files are placed in the [[Nix#Nix store|Nix store]]. The files and directories in <code>/nix/store</code> are named by hashes of the information describing the built data. All of the files and directories placed in the Nix store are immutable. <code>/bin</code> and <code>/usr/bin</code> are almost absent: they contain only <code>/bin/sh</code> and <code>/usr/bin/env</code> respectively, to provide minimal compatibility with existing scripts using shebang lines. User-level environments are implemented using a large number of symbolic links to all required packages and auxiliary files. These environments are called [[Nix#Profiles|profiles]] and are stored in <code>/nix/var/nix/profiles</code>, each user having their own profiles. Structuring the system in this way is how NixOS obtains its key advantages over conventional Linux distributions, such as atomicity and rollback support.
 === Usage of the Nix store ===