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nix(1) General Commands Manual nix(1)

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:

Help commands:

  • nix help - show help about nix or a particular subcommand

  • nix help-stores - show help about store types and their settings

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 profile - manage Nix profiles

  • nix run - run a Nix application

  • nix search - search for packages

  • nix shell - run a shell in which the specified packages are available

Main commands:

•
nix repl - start an interactive environment for evaluating Nix expressions

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 derivation - Work with derivations, Nix’s notion of a build plan.

  • 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 or the value of a specific setting

  • 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

Warning
Installables are part of the unstable nix-command experimental feature, and subject to change without notice.

Many nix subcommands operate on one or more installables. These are command line arguments that represent something that can be realised in the Nix store.

The following types of installable are supported by most commands:

  • Flake output attribute (experimental)

  • Store path

  • Nix file, optionally qualified by an attribute path

  • Nix expression, optionally qualified by an attribute path

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

Flake output attribute

Warning
Flake output attribute installables depend on both the flakes and nix-command experimental features, and subject to change without notice.

Example: 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 path

Example: /nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10

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

A store derivation is also addressed by store path.

Example: /nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv

If you want to refer to an output path of that store derivation, add the output name preceded by a caret (^).

Example: /nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv^out

All outputs can be referred to at once with the special syntax ^*.

Example: /nix/store/p7gp6lxdg32h4ka1q398wd9r2zkbbz2v-hello-2.10.drv^*

Nix file

Example: --file /path/to/nixpkgs hello

When the option -f / --file path [attrpath…] is given, installables are interpreted as the value of the expression in the Nix file at path. If attribute paths are provided, commands will operate on the corresponding values accessible at these paths. The Nix expression in that file, or any selected attribute, must evaluate to a derivation.

Nix expression

Example: --expr 'import <nixpkgs> {}' hello

When the option --expr expression [attrpath…] is given, installables are interpreted as the value of the of the Nix expression. If attribute paths are provided, commands will operate on the corresponding values accessible at these paths. The Nix expression, or any selected attribute, must evaluate to a derivation.

You may need to specify --impure if the expression references impure inputs (such as <nixpkgs>).

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/
…
and likewise, using a store path to a “drv” file to specify the derivation:

# nix build '/nix/store/gzaflydcr6sb3567hap9q6srzx8ggdgg-glibc-2.33-78.drv^dev,static'
…
•
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 --closure-size --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
and likewise, using a store path to a “drv” file to specify the derivation:

# nix path-info --closure-size '/nix/store/gzaflydcr6sb3567hap9q6srzx8ggdgg-glibc-2.33-78.drv^*'
…
•
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.
Note that a store derivation doesn’t have any attributes like meta, and thus this case doesn’t apply to it.
•
Otherwise, Nix will use all outputs of the derivation.

Nix stores

Most nix subcommands operate on a Nix store. These are documented in nix help-stores.

Options

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.

Miscellaneous global 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.

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-allocate-uids
Enable the auto-allocate-uids 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.
•
--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-build-hook value
Append to the build-hook 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.
•
--id-count value
Set the id-count 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.
•
--max-substitution-jobs value
Set the max-substitution-jobs 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-allocate-uids
Disable the auto-allocate-uids 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-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-drop-supplementary-groups
Disable the require-drop-supplementary-groups 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-cgroups
Disable the use-cgroups setting.
•
--no-use-registries
Disable the use-registries setting.
•
--no-use-sqlite-wal
Disable the use-sqlite-wal setting.
•
--no-use-xdg-base-directories
Disable the use-xdg-base-directories 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.
•
--require-drop-supplementary-groups
Enable the require-drop-supplementary-groups 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.
•
--ssl-cert-file value
Set the ssl-cert-file setting.
•
--stalled-download-timeout value
Set the stalled-download-timeout setting.
•
--start-id value
Set the start-id 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-cgroups
Enable the use-cgroups setting.
•
--use-registries
Enable the use-registries setting.
•
--use-sqlite-wal
Enable the use-sqlite-wal setting.
•
--use-xdg-base-directories
Enable the use-xdg-base-directories setting.
•
--user-agent-suffix value
Set the user-agent-suffix setting.
•
--warn-dirty
Enable the warn-dirty setting.