mirror of
https://github.com/NixOS/nix
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fd7f795750
This should help future lost newcomers like myself understand where to find the docs for both of these commands and how they differ.
117 lines
3.5 KiB
Markdown
117 lines
3.5 KiB
Markdown
# Name
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`nix-build` - build a Nix expression
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# Synopsis
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`nix-build` [*paths…*]
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[`--arg` *name* *value*]
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[`--argstr` *name* *value*]
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[{`--attr` | `-A`} *attrPath*]
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[`--no-out-link`]
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[`--dry-run`]
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[{`--out-link` | `-o`} *outlink*]
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# Disambiguation
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This man page describes the command `nix-build`, which is distinct from `nix
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build`. For documentation on the latter, run `nix build --help` or see `man
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nix3-build`.
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# Description
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The `nix-build` command builds the derivations described by the Nix
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expressions in *paths*. If the build succeeds, it places a symlink to
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the result in the current directory. The symlink is called `result`. If
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there are multiple Nix expressions, or the Nix expressions evaluate to
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multiple derivations, multiple sequentially numbered symlinks are
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created (`result`, `result-2`, and so on).
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If no *paths* are specified, then `nix-build` will use `default.nix` in
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the current directory, if it exists.
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If an element of *paths* starts with `http://` or `https://`, it is
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interpreted as the URL of a tarball that will be downloaded and unpacked
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to a temporary location. The tarball must include a single top-level
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directory containing at least a file named `default.nix`.
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`nix-build` is essentially a wrapper around
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[`nix-instantiate`](nix-instantiate.md) (to translate a high-level Nix
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expression to a low-level store derivation) and [`nix-store
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--realise`](nix-store.md#operation---realise) (to build the store
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derivation).
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> **Warning**
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>
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> The result of the build is automatically registered as a root of the
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> Nix garbage collector. This root disappears automatically when the
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> `result` symlink is deleted or renamed. So don’t rename the symlink.
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# Options
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All options not listed here are passed to `nix-store
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--realise`, except for `--arg` and `--attr` / `-A` which are passed to
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`nix-instantiate`.
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- [`--no-out-link`]{#opt-no-out-link}\
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Do not create a symlink to the output path. Note that as a result
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the output does not become a root of the garbage collector, and so
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might be deleted by `nix-store
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--gc`.
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- [`--dry-run`]{#opt-dry-run}\
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Show what store paths would be built or downloaded.
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- [`--out-link`]{#opt-out-link} / `-o` *outlink*\
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Change the name of the symlink to the output path created from
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`result` to *outlink*.
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The following common options are supported:
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# Examples
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```console
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$ nix-build '<nixpkgs>' -A firefox
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store derivation is /nix/store/qybprl8sz2lc...-firefox-1.5.0.7.drv
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/nix/store/d18hyl92g30l...-firefox-1.5.0.7
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$ ls -l result
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lrwxrwxrwx ... result -> /nix/store/d18hyl92g30l...-firefox-1.5.0.7
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$ ls ./result/bin/
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firefox firefox-config
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```
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If a derivation has multiple outputs, `nix-build` will build the default
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(first) output. You can also build all outputs:
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```console
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$ nix-build '<nixpkgs>' -A openssl.all
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```
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This will create a symlink for each output named `result-outputname`.
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The suffix is omitted if the output name is `out`. So if `openssl` has
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outputs `out`, `bin` and `man`, `nix-build` will create symlinks
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`result`, `result-bin` and `result-man`. It’s also possible to build a
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specific output:
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```console
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$ nix-build '<nixpkgs>' -A openssl.man
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```
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This will create a symlink `result-man`.
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Build a Nix expression given on the command line:
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```console
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$ nix-build -E 'with import <nixpkgs> { }; runCommand "foo" { } "echo bar > $out"'
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$ cat ./result
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bar
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```
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Build the GNU Hello package from the latest revision of the master
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branch of Nixpkgs:
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```console
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$ nix-build https://github.com/NixOS/nixpkgs/archive/master.tar.gz -A hello
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```
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