Nix (软件包管理器)

Introduction to Nix

Fundamental concepts

• Nix (language)
• Nix (package manager)
• Nix store

Tools and applications

• Nix (command)
• NixOS

⤧︎

Disambiguation: 本条目介绍的是 Nix 软件包管理器。请勿与 Nix 生态系统、Nix 语言 或 Nix 命令 混淆。

Nix 是一个软件包管理器和构建系统，它解析由 Nix 表达式语言 (惰性求值的纯函数式语言) 指定的可复现的构建指令。Nix 表达式是纯函数，它接受依赖作为参数，并生成一个 derivation，用于指定该软件包的可复现的构建环境。Nix 把构建的结果存储在由完整依赖树的哈希值指定的唯一地址中，从而创建了一个不可变的包存储 (即 nix store)，使得原子升级、回滚、以及同时安装同一软件包的不同版本成为可能，从根本上消除了依赖地狱。

用法

安装

在 NixOS 上，Nix 已经自动安装好了。

如果你想在其他 Linux 发行版或在 macOS 上使用 Nix, 你可以按照 Nix 手册的安装章节来安装 Nix。

Nix 命令

Nix命令被记录在Nix参考手册: 主要命令, 工具命令和实验性命令. 在2.0版本(于2018年2月发布)之前, 命令有所不同.

配置

在NixOS上, Nix通过nix 选项进行配置.

独立的Nix的配置需要通过nix.conf (通常位于 /etc/nix/), 它定义了一系列和求值,构建,垃圾回收,沙盒,以及用户权限的设置. 这些可用选项的细节可在Nix参考手册中找到.

单用户可使用 Home Manager 进一步配置对声明式环境的管理. 对于Linux上的系统级配置, 你可以使用 System Manager. 对于macOS上的系统级配置, nix-darwin 是更佳的解决方案.

内部组成

Nix store(Nix存储库)

↱︎

This section is a candidate for splitting off into a separate article. The nix store is conceptually separate enough that it warrants a separate article. For more information, consult the related discussion page.

Packages built by Nix are placed in the read-only Nix store, normally found in /nix/store. Each package is given a unique address specified by a cryptographic hash followed by the package name and version, for example /nix/store/nawl092prjblbhvv16kxxbk6j9gkgcqm-git-2.14.1. These prefixes hash all the inputs to the build process, including the source files, the full dependency tree, compiler flags, etc. This allows Nix to simultaneously install different versions of the same package, and even different builds of the same version, for example variants built with different compilers. When adding, removing or updating a package, nothing is removed from the store; instead, symlinks to these packages are added, removed or changed in profiles.

Cleaning the Nix store

For information relating to cleaning the Nix store, refer to NixOS Manual: Chapter - Cleaning the Nix Store.

Nix store corruption

For information relating to fixing a corrupted Nix store, refer to NixOS Manual: Chapter - Nix Store Corruption.

Valid Nix store names

Main article: Valid Nix store path names

Profiles(系统画像)

为了建构一个连贯的用户或系统环境, Nix将Nix存储库中的条目符号链接到profile. 这些是Nix允许回滚的"前端": 因为存储库是不可变的, 而且以前的profile版本被保留了下来, 回到更早的状态只需要简单地让符号链接指向一个先前的profile. 更精确地说, Nix将二进制文件符号链接到Nix存储库中描述用户环境的条目中. 这些用户环境随之被符号链接到/nix/var/nix/profiles中带有标签的profile, 而这些profile又被符号链接到用户的~/.nix-profile.

沙盒化

当沙盒构建被启用时, Nix会为每一个构建进程设置一个孤立的环境.It is used to remove further hidden dependencies set by the build environment to improve reproducibility. This includes access to the network during the build outside of fetch* functions and files outside the Nix store. Depending on the operating system access to other resources are blocked as well (ex. inter process communication is isolated on Linux); see nix.conf section in the Nix manual for details.

Sandboxing is enabled by default on Linux, and disabled by default on macOS. In pull requests for Nixpkgs people are asked to test builds with sandboxing enabled (see Tested using sandboxing in the pull request template) because in official Hydra builds sandboxing is also used.

To configure Nix for sandboxing, set sandbox = true in /etc/nix/nix.conf; to configure NixOS for sandboxing set nix.useSandbox = true; in configuration.nix. The nix.useSandbox option is true by default since NixOS 17.09.

可选的解释器

There is an ongoing effort to reimplement Nix, from the ground up, in Rust.

• tvix

There is also a community-led fork of Nix 2.18 named Lix, focused on correctness, usability, and growth. While it has also ported some components of Nix to Rust, it is not a ground-up rewrite like Tvix.

• lix

Earlier attempts can be found on riir-nix

Notes