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


nix - a tool for reproducible and declarative configuration management


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:

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


  • 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!


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.


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

    By default, if you pass a store derivation path to a nix subcommand, the command 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

    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/

    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 -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

    and likewise, using a store path to a "drv" file to specify the derivation:

    # nix path-info -S '/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 (given by its .drv file store path) 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.

TODO: list store types, 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-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.

  • --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-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-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-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.

  • --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.

  • --user-agent-suffix value

    Set the user-agent-suffix setting.

  • --warn-dirty

    Enable the warn-dirty setting.