nix3-build

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 a specific output:

# nix build nixpkgs#glibc.dev
# ls -ld ./result-dev
lrwxrwxrwx 1 ⦠./result-dev -> /nix/store/dkm3gwl0xrx0wrw6zi5x3px3lpgjhlw4-glibc-2.32-dev

•

Build attribute build.x86_64-linux from (non-flake) Nix expression release.nix:

# nix build -f 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.

•

--profile path

The profile to update.

•

--rebuild

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

Common evaluation options:

•

--arg name expr

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

•

--argstr name string

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

•

--eval-store store-url

The Nix store to use for evaluations.

•

--impure

Allow access to mutable paths and repositories.

•

--include / -I path

Add path to the list of locations used to look up <...> file names.

•

--override-flake original-ref resolved-ref

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

Common flake-related options:

•

--commit-lock-file

Commit changes to the flake’s lock file.

•

--inputs-from flake-url

Use the inputs of the specified flake as registry entries.

•

--no-registries

Don’t allow lookups in the flake registries. This option is deprecated; use --no-use-registries.

•

--no-update-lock-file

Do not allow any updates to the flake’s lock file.

•

--no-write-lock-file

Do not write the flake’s newly generated lock file.

•

--override-input input-path flake-url

Override a specific flake input (e.g. dwarffs/nixpkgs). This implies --no-write-lock-file.

•

--recreate-lock-file

Recreate the flake’s lock file from scratch.

•

--update-input input-path

Update a specific flake input (ignoring its previous entry in the lock file).

Options that change the interpretation of installables:

•

--derivation

Operate on the store derivation rather than its outputs.

•

--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.