lix/src/nix/build.md
Valentin Gagarin 2af9fd20c6 clarify definition of "installable"
the term was hard to discover, as its definition and explanation were in
a very long document lacking an overview section.
search did not help because it occurs so often.

- clarify wording in the definition
- add an overview of installable types
- add "installable" to glossary
- link to definition from occurrences of the term
- be more precise about where store derivation outputs are processed
- installable Nix expressions must evaluate to a derivation

Co-authored-by: Adam Joseph <54836058+amjoseph-nixpkgs@users.noreply.github.com>
2023-03-05 01:46:17 +01:00

2.7 KiB

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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 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).

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