# Name

nix-build - build a Nix expression

# Synopsis

nix-build [paths…] [--arg name value] [--argstr name value] [{--attr | -A} attrPath] [--no-out-link] [--dry-run] [{--out-link | -o} outlink]

# Description

The nix-build command builds the derivations described by the Nix expressions in paths. If the build succeeds, it places a symlink to the result in the current directory. The symlink is called result. If there are multiple Nix expressions, or the Nix expressions evaluate to multiple derivations, multiple sequentially numbered symlinks are created (result, result-2, and so on).

If no paths are specified, then nix-build will use default.nix in the current directory, if it exists.

If an element of paths starts with http:// or https://, it is interpreted as the URL of a tarball that will be downloaded and unpacked to a temporary location. The tarball must include a single top-level directory containing at least a file named default.nix.

nix-build is essentially a wrapper around nix-instantiate (to translate a high-level Nix expression to a low-level store derivation) and nix-store --realise (to build the store derivation).

Warning

The result of the build is automatically registered as a root of the Nix garbage collector. This root disappears automatically when the result symlink is deleted or renamed. So don’t rename the symlink.

# Options

All options not listed here are passed to nix-store --realise, except for --arg and --attr / -A which are passed to nix-instantiate.

• --no-out-link\ Do not create a symlink to the output path. Note that as a result the output does not become a root of the garbage collector, and so might be deleted by nix-store --gc.

• --dry-run\ Show what store paths would be built or downloaded.

• --out-link / -o outlink\ Change the name of the symlink to the output path created from result to outlink.

The following common options are supported:

# Examples

$nix-build '<nixpkgs>' -A firefox store derivation is /nix/store/qybprl8sz2lc...-firefox-1.5.0.7.drv /nix/store/d18hyl92g30l...-firefox-1.5.0.7$ ls -l result
lrwxrwxrwx  ...  result -> /nix/store/d18hyl92g30l...-firefox-1.5.0.7

$ls ./result/bin/ firefox firefox-config  If a derivation has multiple outputs, nix-build will build the default (first) output. You can also build all outputs: $ nix-build '<nixpkgs>' -A openssl.all


This will create a symlink for each output named result-outputname. The suffix is omitted if the output name is out. So if openssl has outputs out, bin and man, nix-build will create symlinks result, result-bin and result-man. It’s also possible to build a specific output:

$nix-build '<nixpkgs>' -A openssl.man  This will create a symlink result-man. Build a Nix expression given on the command line: $ nix-build -E 'with import <nixpkgs> { }; runCommand "foo" { } "echo bar > $out"'$ cat ./result
bar


Build the GNU Hello package from the latest revision of the master branch of Nixpkgs:

\$ nix-build https://github.com/NixOS/nixpkgs/archive/master.tar.gz -A hello


Last update: November 4, 2021