nix3-build - Man Page

nix build [option…] installables…

• 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

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).

• --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.

• --no-pretty

  Print compact JSON output on a single line, even when the output is a terminal. Some commands may print multiple JSON objects on separate lines.

            See `--pretty`.

• --out-link / -o path

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

• --pretty

  Print multi-line, indented JSON output for readability.

            Default: indent if output is to a terminal.

            This option is only effective when `--json` is also specified.

• --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.