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 fmt - reformat your code in the standard style
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 stable version declared in Nixpkgs

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 undesirable, 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 packages.system.default (e.g. packages.x86_64-linux.default), 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.

Derivation output selection

Derivations can have multiple outputs, each corresponding to a different store path. For instance, a package can have a bin output that contains programs, and a dev output that provides development artifacts like C/C++ header files. The outputs on which nix commands operate are determined as follows:

You can explicitly specify the desired outputs using the syntax installable^output1,...,outputN. For example, you can obtain the dev and static outputs of the glibc package:
```
# nix build 'nixpkgs#glibc^dev,static'
# ls ./result-dev/include/ ./result-static/lib/
…
```

You can also specify that all outputs should be used using the syntax installable^*. For example, the following shows the size of all outputs of the glibc package in the binary cache:

# nix path-info -S --eval-store auto --store https://cache.nixos.org 'nixpkgs#glibc^*'
/nix/store/g02b1lpbddhymmcjb923kf0l7s9nww58-glibc-2.33-123                 33208200
/nix/store/851dp95qqiisjifi639r0zzg5l465ny4-glibc-2.33-123-bin             36142896
/nix/store/kdgs3q6r7xdff1p7a9hnjr43xw2404z7-glibc-2.33-123-debug          155787312
/nix/store/n4xa8h6pbmqmwnq0mmsz08l38abb06zc-glibc-2.33-123-static          42488328
/nix/store/q6580lr01jpcsqs4r5arlh4ki2c1m9rv-glibc-2.33-123-dev             44200560

If you didn't specify the desired outputs, but the derivation has an attribute meta.outputsToInstall, Nix will use those outputs. For example, since the package nixpkgs#libxml2 has this attribute:
```
# nix eval 'nixpkgs#libxml2.meta.outputsToInstall'
[ "bin" "man" ]
```
a command like nix shell nixpkgs#libxml2 will provide only those two outputs by default.
Otherwise, Nix will use all outputs of the derivation.

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-prefix value
Set the bash-prompt-prefix 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.
--download-speed value
Set the download-speed 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.
--ignore-try
Enable the ignore-try 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-ignore-try
Disable the ignore-try 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-trace-verbose
Disable the trace-verbose 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.
--trace-verbose
Enable the trace-verbose 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.