nix

Warning: This program is experimental and its interface is subject to change.

# Name

`nix` - a tool for reproducible and declarative configuration management

# Synopsis

`nix` [option...] subcommand

where subcommand is one of the following:

Main commands:

- `nix build` - build a derivation or fetch a store path
- `nix develop` - run a bash shell that provides the build environment of a derivation
- `nix flake` - manage Nix flakes
- `nix help` - show help about `nix` or a particular subcommand
- `nix profile` - manage Nix profiles
- `nix repl` - start an interactive environment for evaluating Nix expressions
- `nix run` - run a Nix application
- `nix search` - search for packages
- `nix shell` - run a shell in which the specified packages are available

Infrequently used commands:

- `nix bundle` - bundle an application so that it works outside of the Nix store
- `nix copy` - copy paths between Nix stores
- `nix edit` - open the Nix expression of a Nix package in $EDITOR
- `nix eval` - evaluate a Nix expression
- `nix log` - show the build log of the specified packages or paths, if available
- `nix path-info` - query information about store paths
- `nix registry` - manage the flake registry
- `nix why-depends` - show why a package has another package in its closure

Utility/scripting commands:

- `nix daemon` - daemon to perform store operations on behalf of non-root clients
- `nix describe-stores` - show registered store types and their available options
- `nix hash` - compute and convert cryptographic hashes
- `nix key` - generate and convert Nix signing keys
- `nix nar` - create or inspect NAR files
- `nix print-dev-env` - print shell code that can be sourced by bash to reproduce the build environment of a derivation
- `nix realisation` - manipulate a Nix realisation
- `nix show-config` - show the Nix configuration
- `nix show-derivation` - show the contents of a store derivation
- `nix store` - manipulate a Nix store

Commands for upgrading or troubleshooting your Nix installation:

- `nix doctor` - check your system for potential problems and print a PASS or FAIL for each check
- `nix upgrade-nix` - upgrade Nix to the latest stable version

# Examples

- Create a new flake:

      # nix flake new hello
      # cd hello

- Build the flake in the current directory:

      # nix build
      # ./result/bin/hello
      Hello, world!

- Run the flake in the current directory:

      # nix run
      Hello, world!

- Start a development shell for hacking on this flake:

      # nix develop
      # unpackPhase
      # cd hello-*
      # configurePhase
      # buildPhase
      # ./hello
      Hello, world!
      # installPhase
      # ../outputs/out/bin/hello
      Hello, world!

# Description

Nix is a tool for building software, configurations and other artifacts in a reproducible and declarative way. For more information, see the Nix homepage or the Nix manual.

# Installables

Many `nix` subcommands operate on one or more installables. These are command line arguments that represent something that can be built in the Nix store. Here are the recognised types of installables:

- Flake output attributes: `nixpkgs#hello`

  These have the form flakeref[`#`attrpath], where flakeref is a flake reference and attrpath is an optional attribute path. For more information on flakes, see the `nix flake` manual page. Flake references are most commonly a flake identifier in the flake registry (e.g. `nixpkgs`), or a raw path (e.g. `/path/to/my-flake` or `.` or `../foo`), or a full URL (e.g. `github:nixos/nixpkgs` or `path:.`)

  When the flake reference is a raw path (a path without any URL scheme), it is interpreted as a `path:` or `git+file:` url in the following way:

  - If the path is within a Git repository, then the url will be of the form `git+file://[GIT_REPO_ROOT]?dir=[RELATIVE_FLAKE_DIR_PATH]` where `GIT_REPO_ROOT` is the path to the root of the git repository, and `RELATIVE_FLAKE_DIR_PATH` is the path (relative to the directory root) of the closest parent of the given path that contains a `flake.nix` within the git repository. If no such directory exists, then Nix will error-out.

    Note that the search will only include files indexed by git. In particular, files which are matched by `.gitignore` or have never been `git add`-ed will not be available in the flake. If this is undesireable, specify `path:<directory>` explicitly;

    For example, if `/foo/bar` is a git repository with the following structure:

        .
        └── baz
            ├── blah
            │   └── file.txt
            └── flake.nix

  Then `/foo/bar/baz/blah` will resolve to `git+file:///foo/bar?dir=baz`

  - If the supplied path is not a git repository, then the url will have the form `path:FLAKE_DIR_PATH` where `FLAKE_DIR_PATH` is the closest parent of the supplied path that contains a `flake.nix` file (within the same file-system). If no such directory exists, then Nix will error-out.

    For example, if `/foo/bar/flake.nix` exists, then `/foo/bar/baz/` will resolve to `path:/foo/bar`

  If attrpath is omitted, Nix tries some default values; for most subcommands, the default is `defaultPackage.`system (e.g. `defaultPackage.x86_64-linux`), but some subcommands have other defaults. If attrpath is specified, attrpath is interpreted as relative to one or more prefixes; for most subcommands, these are `packages.`system, `legacyPackages.*system*` and the empty prefix. Thus, on `x86_64-linux` `nix build nixpkgs#hello` will try to build the attributes `packages.x86_64-linux.hello`, `legacyPackages.x86_64-linux.hello` and `hello`.

- Store paths: `/nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10`

  These are paths inside the Nix store, or symlinks that resolve to a path in the Nix store.

- Store derivations: `/nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv`

  Store derivations are store paths with extension `.drv` and are a low-level representation of a build-time dependency graph used internally by Nix. By default, if you pass a store derivation to a `nix` subcommand, it will operate on the output paths of the derivation. For example, `nix path-info` prints information about the output paths:

      # nix path-info --json /nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv
      [{"path":"/nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10",…}]

  If you want to operate on the store derivation itself, pass the `--derivation` flag.

- Nix attributes: `--file /path/to/nixpkgs hello`

  When the `-f` / `--file` path option is given, installables are interpreted as attribute paths referencing a value returned by evaluating the Nix file path.

- Nix expressions: `--expr '(import <nixpkgs> {}).hello.overrideDerivation (prev: { name = "my-hello"; })'`.

  When the `--expr` option is given, all installables are interpreted as Nix expressions. You may need to specify `--impure` if the expression references impure inputs (such as `<nixpkgs>`).

For most commands, if no installable is specified, the default is `.`, i.e. Nix will operate on the default flake output attribute of the flake in the current directory.

# Nix stores

Most `nix` subcommands operate on a Nix store.

TODO: list store types, options

# Options

- `--help`
  Show usage information.

- `--offline`
  Disable substituters and consider all previously downloaded files up-to-date.

- `--option` name value
  Set the Nix configuration setting name to value (overriding `nix.conf`).

- `--refresh`
  Consider all previously downloaded files out-of-date.

- `--version`
  Show version information.

Logging-related options:

- `--debug`
  Set the logging verbosity level to 'debug'.

- `--log-format` format
  Set the format of log output; one of `raw`, `internal-json`, `bar` or `bar-with-logs`.

- `--print-build-logs` / `-L`
  Print full build logs on standard error.

- `--quiet`
  Decrease the logging verbosity level.

- `--verbose` / `-v`
  Increase the logging verbosity level.

Options to override configuration settings:

- `--accept-flake-config`
  Enable the `accept-flake-config` setting.

- `--access-tokens` value
  Set the `access-tokens` setting.

- `--allow-dirty`
  Enable the `allow-dirty` setting.

- `--allow-import-from-derivation`
  Enable the `allow-import-from-derivation` setting.

- `--allow-new-privileges`
  Enable the `allow-new-privileges` setting.

- `--allow-symlinked-store`
  Enable the `allow-symlinked-store` setting.

- `--allow-unsafe-native-code-during-evaluation`
  Enable the `allow-unsafe-native-code-during-evaluation` setting.

- `--allowed-impure-host-deps` value
  Set the `allowed-impure-host-deps` setting.

- `--allowed-uris` value
  Set the `allowed-uris` setting.

- `--allowed-users` value
  Set the `allowed-users` setting.

- `--auto-optimise-store`
  Enable the `auto-optimise-store` setting.

- `--bash-prompt` value
  Set the `bash-prompt` setting.

- `--bash-prompt-suffix` value
  Set the `bash-prompt-suffix` setting.

- `--build-hook` value
  Set the `build-hook` setting.

- `--build-poll-interval` value
  Set the `build-poll-interval` setting.

- `--build-users-group` value
  Set the `build-users-group` setting.

- `--builders` value
  Set the `builders` setting.

- `--builders-use-substitutes`
  Enable the `builders-use-substitutes` setting.

- `--commit-lockfile-summary` value
  Set the `commit-lockfile-summary` setting.

- `--compress-build-log`
  Enable the `compress-build-log` setting.

- `--connect-timeout` value
  Set the `connect-timeout` setting.

- `--cores` value
  Set the `cores` setting.

- `--diff-hook` value
  Set the `diff-hook` setting.

- `--download-attempts` value
  Set the `download-attempts` setting.

- `--enforce-determinism`
  Enable the `enforce-determinism` setting.

- `--eval-cache`
  Enable the `eval-cache` setting.

- `--experimental-features` value
  Set the `experimental-features` setting.

- `--extra-access-tokens` value
  Append to the `access-tokens` setting.

- `--extra-allowed-impure-host-deps` value
  Append to the `allowed-impure-host-deps` setting.

- `--extra-allowed-uris` value
  Append to the `allowed-uris` setting.

- `--extra-allowed-users` value
  Append to the `allowed-users` setting.

- `--extra-experimental-features` value
  Append to the `experimental-features` setting.

- `--extra-extra-platforms` value
  Append to the `extra-platforms` setting.

- `--extra-hashed-mirrors` value
  Append to the `hashed-mirrors` setting.

- `--extra-ignored-acls` value
  Append to the `ignored-acls` setting.

- `--extra-nix-path` value
  Append to the `nix-path` setting.

- `--extra-platforms` value
  Set the `extra-platforms` setting.

- `--extra-plugin-files` value
  Append to the `plugin-files` setting.

- `--extra-sandbox-paths` value
  Append to the `sandbox-paths` setting.

- `--extra-secret-key-files` value
  Append to the `secret-key-files` setting.

- `--extra-substituters` value
  Append to the `substituters` setting.

- `--extra-system-features` value
  Append to the `system-features` setting.

- `--extra-trusted-public-keys` value
  Append to the `trusted-public-keys` setting.

- `--extra-trusted-substituters` value
  Append to the `trusted-substituters` setting.

- `--extra-trusted-users` value
  Append to the `trusted-users` setting.

- `--fallback`
  Enable the `fallback` setting.

- `--filter-syscalls`
  Enable the `filter-syscalls` setting.

- `--flake-registry` value
  Set the `flake-registry` setting.

- `--fsync-metadata`
  Enable the `fsync-metadata` setting.

- `--gc-reserved-space` value
  Set the `gc-reserved-space` setting.

- `--hashed-mirrors` value
  Set the `hashed-mirrors` setting.

- `--http-connections` value
  Set the `http-connections` setting.

- `--http2`
  Enable the `http2` setting.

- `--ignored-acls` value
  Set the `ignored-acls` setting.

- `--impersonate-linux-26`
  Enable the `impersonate-linux-26` setting.

- `--keep-build-log`
  Enable the `keep-build-log` setting.

- `--keep-derivations`
  Enable the `keep-derivations` setting.

- `--keep-env-derivations`
  Enable the `keep-env-derivations` setting.

- `--keep-failed`
  Enable the `keep-failed` setting.

- `--keep-going`
  Enable the `keep-going` setting.

- `--keep-outputs`
  Enable the `keep-outputs` setting.

- `--log-lines` value
  Set the `log-lines` setting.

- `--max-build-log-size` value
  Set the `max-build-log-size` setting.

- `--max-free` value
  Set the `max-free` setting.

- `--max-jobs` value
  Set the `max-jobs` setting.

- `--max-silent-time` value
  Set the `max-silent-time` setting.

- `--min-free` value
  Set the `min-free` setting.

- `--min-free-check-interval` value
  Set the `min-free-check-interval` setting.

- `--nar-buffer-size` value
  Set the `nar-buffer-size` setting.

- `--narinfo-cache-negative-ttl` value
  Set the `narinfo-cache-negative-ttl` setting.

- `--narinfo-cache-positive-ttl` value
  Set the `narinfo-cache-positive-ttl` setting.

- `--netrc-file` value
  Set the `netrc-file` setting.

- `--nix-path` value
  Set the `nix-path` setting.

- `--no-accept-flake-config`
  Disable the `accept-flake-config` setting.

- `--no-allow-dirty`
  Disable the `allow-dirty` setting.

- `--no-allow-import-from-derivation`
  Disable the `allow-import-from-derivation` setting.

- `--no-allow-new-privileges`
  Disable the `allow-new-privileges` setting.

- `--no-allow-symlinked-store`
  Disable the `allow-symlinked-store` setting.

- `--no-allow-unsafe-native-code-during-evaluation`
  Disable the `allow-unsafe-native-code-during-evaluation` setting.

- `--no-auto-optimise-store`
  Disable the `auto-optimise-store` setting.

- `--no-builders-use-substitutes`
  Disable the `builders-use-substitutes` setting.

- `--no-compress-build-log`
  Disable the `compress-build-log` setting.

- `--no-enforce-determinism`
  Disable the `enforce-determinism` setting.

- `--no-eval-cache`
  Disable the `eval-cache` setting.

- `--no-fallback`
  Disable the `fallback` setting.

- `--no-filter-syscalls`
  Disable the `filter-syscalls` setting.

- `--no-fsync-metadata`
  Disable the `fsync-metadata` setting.

- `--no-http2`
  Disable the `http2` setting.

- `--no-impersonate-linux-26`
  Disable the `impersonate-linux-26` setting.

- `--no-keep-build-log`
  Disable the `keep-build-log` setting.

- `--no-keep-derivations`
  Disable the `keep-derivations` setting.

- `--no-keep-env-derivations`
  Disable the `keep-env-derivations` setting.

- `--no-keep-failed`
  Disable the `keep-failed` setting.

- `--no-keep-going`
  Disable the `keep-going` setting.

- `--no-keep-outputs`
  Disable the `keep-outputs` setting.

- `--no-preallocate-contents`
  Disable the `preallocate-contents` setting.

- `--no-print-missing`
  Disable the `print-missing` setting.

- `--no-pure-eval`
  Disable the `pure-eval` setting.

- `--no-require-sigs`
  Disable the `require-sigs` setting.

- `--no-restrict-eval`
  Disable the `restrict-eval` setting.

- `--no-run-diff-hook`
  Disable the `run-diff-hook` setting.

- `--no-sandbox`
  Disable sandboxing.

- `--no-sandbox-fallback`
  Disable the `sandbox-fallback` setting.

- `--no-show-trace`
  Disable the `show-trace` setting.

- `--no-substitute`
  Disable the `substitute` setting.

- `--no-sync-before-registering`
  Disable the `sync-before-registering` setting.

- `--no-trace-function-calls`
  Disable the `trace-function-calls` setting.

- `--no-use-case-hack`
  Disable the `use-case-hack` setting.

- `--no-use-registries`
  Disable the `use-registries` setting.

- `--no-use-sqlite-wal`
  Disable the `use-sqlite-wal` setting.

- `--no-warn-dirty`
  Disable the `warn-dirty` setting.

- `--plugin-files` value
  Set the `plugin-files` setting.

- `--post-build-hook` value
  Set the `post-build-hook` setting.

- `--pre-build-hook` value
  Set the `pre-build-hook` setting.

- `--preallocate-contents`
  Enable the `preallocate-contents` setting.

- `--print-missing`
  Enable the `print-missing` setting.

- `--pure-eval`
  Enable the `pure-eval` setting.

- `--relaxed-sandbox`
  Enable sandboxing, but allow builds to disable it.

- `--repeat` value
  Set the `repeat` setting.

- `--require-sigs`
  Enable the `require-sigs` setting.

- `--restrict-eval`
  Enable the `restrict-eval` setting.

- `--run-diff-hook`
  Enable the `run-diff-hook` setting.

- `--sandbox`
  Enable sandboxing.

- `--sandbox-build-dir` value
  Set the `sandbox-build-dir` setting.

- `--sandbox-dev-shm-size` value
  Set the `sandbox-dev-shm-size` setting.

- `--sandbox-fallback`
  Enable the `sandbox-fallback` setting.

- `--sandbox-paths` value
  Set the `sandbox-paths` setting.

- `--secret-key-files` value
  Set the `secret-key-files` setting.

- `--show-trace`
  Enable the `show-trace` setting.

- `--stalled-download-timeout` value
  Set the `stalled-download-timeout` setting.

- `--store` value
  Set the `store` setting.

- `--substitute`
  Enable the `substitute` setting.

- `--substituters` value
  Set the `substituters` setting.

- `--sync-before-registering`
  Enable the `sync-before-registering` setting.

- `--system` value
  Set the `system` setting.

- `--system-features` value
  Set the `system-features` setting.

- `--tarball-ttl` value
  Set the `tarball-ttl` setting.

- `--timeout` value
  Set the `timeout` setting.

- `--trace-function-calls`
  Enable the `trace-function-calls` setting.

- `--trusted-public-keys` value
  Set the `trusted-public-keys` setting.

- `--trusted-substituters` value
  Set the `trusted-substituters` setting.

- `--trusted-users` value
  Set the `trusted-users` setting.

- `--use-case-hack`
  Enable the `use-case-hack` setting.

- `--use-registries`
  Enable the `use-registries` setting.

- `--use-sqlite-wal`
  Enable the `use-sqlite-wal` setting.

- `--user-agent-suffix` value
  Set the `user-agent-suffix` setting.

- `--warn-dirty`
  Enable the `warn-dirty` setting.