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

Name

nix build - build a derivation or fetch a store path

Synopsis

nix build [option...] installables...

Examples

  • Build the default package from the flake in the current directory:

    # nix build
    
  • Build and run GNU Hello from the nixpkgs flake:

    # nix build nixpkgs#hello
    # ./result/bin/hello
    Hello, world!
    
  • Build GNU Hello and Cowsay, leaving two result symlinks:

    # nix build nixpkgs#hello nixpkgs#cowsay
    # ls -l result*
    lrwxrwxrwx 1 … result -> /nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10
    lrwxrwxrwx 1 … result-1 -> /nix/store/rkfrm0z6x6jmi7d3gsmma4j53h15mg33-cowsay-3.03+dfsg2
    
  • Build GNU Hello and print the resulting store path.

    # nix build nixpkgs#hello --print-out-paths
    /nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10
    
  • Build a specific output:

    # nix build nixpkgs#glibc.dev
    # ls -ld ./result-dev
    lrwxrwxrwx 1 … ./result-dev -> /nix/store/dkm3gwl0xrx0wrw6zi5x3px3lpgjhlw4-glibc-2.32-dev
    
  • Build all outputs:

    # nix build "nixpkgs#openssl^*" --print-out-paths
    /nix/store/gvad6v0cmq1qccmc4wphsazqbj0xzjsl-openssl-3.0.13-bin
    /nix/store/a07jqdrc8afnk8r6f3lnhh4gvab7chk4-openssl-3.0.13-debug
    /nix/store/yg75achq89wgqn2fi3gglgsd77kjpi03-openssl-3.0.13-dev
    /nix/store/bvdcihi8c88fw31cg6gzzmpnwglpn1jv-openssl-3.0.13-doc
    /nix/store/gjqcvq47cmxazxga0cirspm3jywkmvfv-openssl-3.0.13-man
    /nix/store/7nmrrad8skxr47f9hfl3xc0pfqmwq51b-openssl-3.0.13
    
  • Build attribute build.x86_64-linux from (non-flake) Nix expression release.nix:

    # nix build --file release.nix build.x86_64-linux
    
  • Build a NixOS system configuration from a flake, and make a profile point to the result:

    # nix build --profile /nix/var/nix/profiles/system \
        ~/my-configurations#nixosConfigurations.machine.config.system.build.toplevel
    

    (This is essentially what nixos-rebuild does.)

  • Build an expression specified on the command line:

    # nix build --impure --expr \
        'with import <nixpkgs> {};
         runCommand "foo" {
           buildInputs = [ hello ];
         }
         "hello > $out"'
    # cat ./result
    Hello, world!
    

    Note that --impure is needed because we're using <nixpkgs>, which relies on the $NIX_PATH environment variable.

  • Fetch a store path from the configured substituters, if it doesn't already exist:

    # nix build /nix/store/rkfrm0z6x6jmi7d3gsmma4j53h15mg33-cowsay-3.03+dfsg2
    

Description

nix build builds the specified installables. Installables that resolve to derivations are built (or substituted if possible). Store path installables are substituted.

Unless --no-link is specified, after a successful build, it creates symlinks to the store paths of the installables. These symlinks have the prefix ./result by default; this can be overridden using the --out-link option. Each symlink has a suffix -<N>-<outname>, where N is the index of the installable (with the left-most installable having index 0), and outname is the symbolic derivation output name (e.g. bin, dev or lib). -<N> is omitted if N = 0, and -<outname> is omitted if outname = out (denoting the default output).

Options

  • --dry-run

    Show what this command would do without doing it.

  • --json

    Produce output in JSON format, suitable for consumption by another program.

  • --no-link

    Do not create symlinks to the build results.

  • --out-link / -o path

    Use path as prefix for the symlinks to the build results. It defaults to result.

  • --print-out-paths

    Print the resulting output paths

  • --profile path

    The profile to operate on.

  • --rebuild

    Rebuild an already built package and compare the result to the existing store paths.

  • --stdin

    Read installables from the standard input. No default installable applied.

Common evaluation options

  • --arg name expr

    Pass the value expr as the argument name to Nix functions.

  • --arg-from-file name path

    Pass the contents of file path as the argument name to Nix functions.

  • --arg-from-stdin name

    Pass the contents of stdin as the argument name to Nix functions.

  • --argstr name string

    Pass the string string as the argument name to Nix functions.

  • --debugger

    Start an interactive environment if evaluation fails.

  • --eval-store store-url

    The URL of the Nix store to use for evaluation, i.e. to store derivations (.drv files) and inputs referenced by them.

  • --impure

    Allow access to mutable paths and repositories.

  • --include / -I path

    Add path to search path entries used to resolve lookup paths

    This option may be given multiple times.

    Paths added through -I take precedence over the nix-path configuration setting and the NIX_PATH environment variable.

  • --override-flake original-ref resolved-ref

    Override the flake registries, redirecting original-ref to resolved-ref.

  • --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.

  • --repair

    During evaluation, rewrite missing or corrupted files in the Nix store. During building, rebuild missing or corrupted store paths.

  • --version

    Show version information.

Options that change the interpretation of installables

  • --expr expr

    Interpret installables as attribute paths relative to the Nix expression expr.

  • --file / -f file

    Interpret installables as attribute paths relative to the Nix expression stored in file. If file is the character -, then a Nix expression will be read from standard input. Implies --impure.

Note

See man nix.conf for overriding configuration settings with command line flags.