### Configure Meson installation tags

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example of setting mesonInstallTags as a list of strings.

```nix
mesonInstallTags = [ "emulator" "assembler" ];
```

--------------------------------

### Example configuration values

Source: https://nixos.org/manual/nixpkgs/unstable

Examples for specific configuration fields.

```nix
[
  "ut1999"
]
```

```nix
"it's dangerous."
```

--------------------------------

### Cross-build using system examples

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Instantiate a cross-build using a predefined system example.

```bash
$ nix-build '<nixpkgs>' --arg crossSystem '(import <nixpkgs/lib>).systems.examples.fooBarBaz' -A whatever
```

--------------------------------

### Initialize libglycin build environment

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example setup for a Rust package using libglycin and glycin-loaders within a Nix derivation.

```nix
{
  lib,
  rustPlatform,
  libglycin,
  glycin-loaders,
  wrapGAppsHook4,
}:

rustPlatform.buildRustPackage {
```

--------------------------------

### Use mkPackageOption

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Examples of creating package options with various configurations for defaults, examples, and nullability.

```nix
mkPackageOption pkgs "hello" { }
=> { ...; default = pkgs.hello; defaultText = literalExpression "pkgs.hello"; description = "The hello package to use."; type = package; }

mkPackageOption pkgs "GHC" {
  default = [ "ghc" ];
  example = "pkgs.haskellPackages.ghc.withPackages (hkgs: [ hkgs.primes ])";
}
=> { ...; default = pkgs.ghc; defaultText = literalExpression "pkgs.ghc"; description = "The GHC package to use."; example = literalExpression "pkgs.haskellPackages.ghc.withPackages (hkgs: [ hkgs.primes ])"; type = package; }

mkPackageOption pkgs [ "python3Packages" "pytorch" ] {
  extraDescription = "This is an example and doesn't actually do anything.";
}
=> { ...; default = pkgs.python3Packages.pytorch; defaultText = literalExpression "pkgs.python3Packages.pytorch"; description = "The pytorch package to use. This is an example and doesn't actually do anything."; type = package; }

mkPackageOption pkgs "nushell" {
  nullable = true;
}
=> { ...; default = pkgs.nushell; defaultText = literalExpression "pkgs.nushell"; description = "The nushell package to use."; type = nullOr package; }

mkPackageOption pkgs "coreutils" {
  default = null;
}
=> { ...; description = "The coreutils package to use."; type = package; }
```

--------------------------------

### Example gitConfig

Source: https://nixos.org/manual/nixpkgs/unstable

An example configuration for overriding URLs to point to local mirrors.

```nix
{
  url = {
    "https://my-github-mirror.local" = {
      insteadOf = [
        "https://github.com"
      ];
    };
  };
}
```

--------------------------------

### lib.fileset.fromSource usage examples

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Examples demonstrating how to convert existing sources to file sets and perform operations like difference.

```nix
# There's no cleanSource-like function for file sets yet,
# but we can just convert cleanSource to a file set and use it that way
toSource {
  root = ./.;
  fileset = fromSource (lib.sources.cleanSource ./.);
}
```

```nix
# Keeping a previous sourceByRegex (which could be migrated to `lib.fileset.unions`),
# but removing a subdirectory using file set functions
difference
  (fromSource (lib.sources.sourceByRegex ./. [
    "^README\\.md$"
    # This regex includes everything in ./doc
    "^doc(/.*)?$"
  ])
  ./doc/generated
```

--------------------------------

### Usage examples for lib.fileset.toSource

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Examples demonstrating how to import directories and files into the store, including handling of unions and error cases for files outside the root.

```nix
# Import the current directory into the store
# but only include files under ./src
toSource {
  root = ./.;
  fileset = ./src;
}
=> "/nix/store/...-source"
```

```nix
# Import the current directory into the store
# but only include ./Makefile and all files under ./src
toSource {
  root = ./.;
  fileset = union
    ./Makefile
    ./src;
}
=> "/nix/store/...-source"
```

```nix
# Trying to include a file outside the root will fail
toSource {
  root = ./.;
  fileset = unions [
    ./Makefile
    ./src
    ../LICENSE
  ];
}
=> <error>
```

--------------------------------

### Configure Nixpkgs to allow unfree packages

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example of a user-specific configuration file to enable the installation of unfree software.

```nix
{ allowUnfree = true; }
```

--------------------------------

### Install executables with installBin

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Use installBin to place files into outputBin. Rename files before installation if the source name is undesirable.

```nix
{
  nativeBuildInputs = [ installShellFiles ];

  # Sometimes the file has an undesirable name. It should be renamed before
  # being installed via installBin
  postInstall = ''
    mv a.out delmar
    installBin foobar delmar
  '';
}
```

--------------------------------

### Create a complex setup hook with substitutions

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Demonstrates a setup hook that uses substitutions to inject paths to dependencies and registers a function to preConfigureHooks.

```nix
pkgs.makeSetupHook
  {
    name = "run-hello-hook";
    # Put dependencies here if they have hooks or necessary dependencies propagated
    # otherwise prefer direct paths to executables.
    propagatedBuildInputs = [
      pkgs.hello
      pkgs.cowsay
    ];
    substitutions = {
      shell = "${pkgs.bash}/bin/bash";
      cowsay = "${pkgs.cowsay}/bin/cowsay";
    };
  }
  (
    writeScript "run-hello-hook.sh" ''
      #!@shell@
      # the direct path to the executable has to be here because
      # this will be run when the file is sourced
      # at which point '$PATH' has not yet been populated with inputs
      @cowsay@ cow

      _printHelloHook() {
        hello
      }
      preConfigureHooks+=(_printHelloHook)
    ''
  )
```

--------------------------------

### Install Shell Completions

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Demonstrates explicit and implicit shell completion installation using installShellCompletion.

```nix
{
  nativeBuildInputs = [ installShellFiles ];
  postInstall = ''
    # explicit behavior
    installShellCompletion --bash --name foobar.bash share/completions.bash
    installShellCompletion --fish --name foobar.fish share/completions.fish
    installShellCompletion --nushell --name foobar share/completions.nu
    installShellCompletion --zsh --name _foobar share/completions.zsh
    # implicit behavior
    installShellCompletion share/completions/foobar.{bash,fish,zsh,nu}
  '';
}
```

--------------------------------

### Example flake configuration

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

A complete flake example demonstrating how to define the darwin-builder and integrate it into darwinConfigurations.

```nix
{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-22.11-darwin";
    darwin.url = "github:nix-darwin/nix-darwin/master";
    darwin.inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs =
    {
      self,
      darwin,
      nixpkgs,
      ...
    }@inputs:
    let

      inherit (darwin.lib) darwinSystem;
      system = "aarch64-darwin";
      pkgs = nixpkgs.legacyPackages."${system}";
      linuxSystem = builtins.replaceStrings [ "darwin" ] [ "linux" ] system;

      darwin-builder = nixpkgs.lib.nixosSystem {
        system = linuxSystem;
        modules = [
          "${nixpkgs}/nixos/modules/profiles/nix-builder-vm.nix"
          {
            virtualisation = {
              host.pkgs = pkgs;
              darwin-builder.workingDirectory = "/var/lib/darwin-builder";
              darwin-builder.hostPort = 22;
            };
          }
        ];
      };
    in
    {

      darwinConfigurations = {
        machine1 = darwinSystem {
          inherit system;
          modules = [
            {
              nix.distributedBuilds = true;
              nix.buildMachines = [
                {
                  hostName = "localhost";
                  sshUser = "builder";
                  sshKey = "/etc/nix/builder_ed25519";
                  system = linuxSystem;
                  maxJobs = 4;
                  supportedFeatures = [
                    "kvm"
                    "benchmark"
                    "big-parallel"
                  ];
                }
              ];

              launchd.daemons.darwin-builder = {
                command = "${darwin-builder.config.system.build.macos-builder-installer}/bin/create-builder";
                serviceConfig = {
                  KeepAlive = true;
                  RunAtLoad = true;
                  StandardOutPath = "/var/log/darwin-builder.log";
                  StandardErrorPath = "/var/log/darwin-builder.log";
                };
              };
            }
          ];
        };
      };

    };
}
```

--------------------------------

### Define a basic setup hook with makeSetupHook

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Creates a simple setup hook by specifying dependencies and a path to a shell script.

```nix
pkgs.makeSetupHook {
  name = "something-hook";
  propagatedBuildInputs = [ pkgs.commandsomething ];
  depsTargetTargetPropagated = [ pkgs.libsomething ];
} ./script.sh
```

--------------------------------

### Configure buildDubPackage attributes

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example configuration for a D package build, including lockfile specification and custom install phase.

```nix
  # generated by dub-to-nix, see below
  dubLock = ./dub-lock.json;

  buildInputs = [
    ncurses
    zlib
  ];

  installPhase = ''
    runHook preInstall
    install -Dm755 btdu -t $out/bin
    runHook postInstall
  '';
}
```

--------------------------------

### Install Manpage

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Installs a manpage from a file using the installManPage hook.

```nix
postInstall = ''
    installManPage -- --name
  '';
```

--------------------------------

### installBin

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Installs one or more files as executable binaries into the outputBin directory.

```APIDOC
## installBin

### Description
Takes one or more paths to files and installs them as executable files into the `outputBin` directory.

### Usage
`installBin <file1> [file2 ...]`
```

--------------------------------

### Usage examples for lib.fixedPoints.extends

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Various scenarios for extending fixed-point functions.

```nix
f = final: { a = 1; b = final.a + 2; }

fix f
=> { a = 1; b = 3; }

fix (extends (final: prev: { a = prev.a + 10; }) f)
=> { a = 11; b = 13; }

fix (extends (final: prev: { b = final.a + 5; }) f)
=> { a = 1; b = 6; }

fix (extends (final: prev: { c = final.a + final.b; }) f)
=> { a = 1; b = 3; c = 4; }
```

--------------------------------

### Full Crystal Package Build Example

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

A complete example of a Nix expression for building a Crystal package with dependencies.

```nix
with import <nixpkgs> { };
crystal.buildCrystalPackage rec {
  version = "0.5.0";
  pname = "mint";
  src = fetchFromGitHub {
    owner = "mint-lang";
    repo = "mint";
    tag = version;
    hash = "sha256-dFN9l5fgrM/TtOPqlQvUYgixE4KPr629aBmkwdDoq28=";
  };

  shardsFile = ./shards.nix;
  crystalBinaries.mint.src = "src/mint.cr";

  buildInputs = [ openssl ];
}
```

--------------------------------

### Override build and install phases

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Demonstrates manual compilation and installation by overriding the default buildPhase and installPhase attributes.

```nix
stdenv.mkDerivation {
  pname = "fnord";
  version = "4.5";

  # ...

  buildPhase = ''
    runHook preBuild

    gcc foo.c -o foo

    runHook postBuild
  '';

  installPhase = ''
    runHook preInstall

    mkdir -p $out/bin
    cp foo $out/bin

    runHook postInstall
  '';
}
```

--------------------------------

### Setup MPI check phase hook

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example of including the mpiCheckPhaseHook in a derivation.

```nix
{ mpiCheckPhaseHook, mpi, ... }:
{

```

--------------------------------

### Using postgresqlTestHook

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Basic setup for using postgresqlTestHook to start a database server during the checkPhase.

```nix
{
  stdenv,
  postgresql,
  postgresqlTestHook,
}:
stdenv.mkDerivation {
```

--------------------------------

### Configure Emscripten Package Phases

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example of overriding build phases like configure, build, and install for an Emscripten package, including environment variable adjustments.

```nix
  # we need to reset this setting!
  env = (old.env or { }) // {
    NIX_CFLAGS_COMPILE = "";
  };

  configurePhase = ''
    # FIXME: Some tests require writing at $HOME
    HOME=$TMPDIR
    runHook preConfigure

    #export EMCC_DEBUG=2
    emconfigure ./configure --prefix=$out --shared

    runHook postConfigure
  '';

  dontStrip = true;
  outputs = [ "out" ];

  buildPhase = ''
    runHook preBuild

    emmake make

    runHook postBuild
  '';

  installPhase = ''
    runHook preInstall

    emmake make install

    runHook postInstall
  '';

  checkPhase = ''
    runHook preCheck

    echo "================= testing zlib using node ================="

    echo "Compiling a custom test"
    set -x
    emcc -O2 -s EMULATE_FUNCTION_POINTER_CASTS=1 test/example.c -DZ_SOLO \
    libz.so.${old.version} -I . -o example.js

    echo "Using node to execute the test"
    ${pkgs.nodejs}/bin/node ./example.js

    set +x
    if [ $? -ne 0 ]; then
      echo "test failed for some reason"
      exit 1;
    else
      echo "it seems to work! very good."
    fi
    echo "================= /testing zlib using node ================="

    runHook postCheck
  '';

  postPatch = pkgs.lib.optionalString pkgs.stdenv.hostPlatform.isDarwin ''
    substituteInPlace configure \
      --replace-fail '/usr/bin/libtool' 'ar' \
      --replace-fail 'AR="libtool"' 'AR="ar"' \
      --replace-fail 'ARFLAGS="-o"' 'ARFLAGS="-r"'
  '';
})
```

--------------------------------

### Define meta.teams example

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example usage of the meta.teams option.

```nix
[ lib.teams.acme lib.teams.haskell ]
```

--------------------------------

### Define meta.maintainers example

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example usage of the meta.maintainers option.

```nix
[ lib.maintainers.alice lib.maintainers.bob ]
```

--------------------------------

### Initialize nix-shell for package building

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Prepare the environment by setting the output directory before running build phases.

```bash
cd "$(mktemp -d)"
nix-shell '<nixpkgs>' -A some_package
export out=$(pwd)/out
```

--------------------------------

### Install with mods

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Apply specific mods to the Cataclysm DDA installation.

```nix
cataclysm-dda.withMods (mods: with mods; [ tileset.UndeadPeople ])
```

--------------------------------

### Update Nixpkgs Configuration to use lib

Source: https://nixos.org/manual/nixpkgs/unstable/release-notes

Examples showing the transition from using pkgs to lib in Nixpkgs configuration for improved performance and recursion safety.

```nix
  { pkgs, ... }:
  {
    allowlistedLicenses = [ pkgs.lib.licenses.nasa13 ];
    blocklistedLicenses = with pkgs.lib.licenses; [ gpl3Only gpl3Plus ];
  }
```

```nix
  { lib, ... }:
  {
    allowlistedLicenses = [ lib.licenses.nasa13 ];
    blocklistedLicenses = with lib.licenses; [ gpl3Only gpl3Plus ];
  }
```

```nix
  { pkgs, lib ? pkgs.lib, ... }:
  {
    allowlistedLicenses = [ lib.licenses.nasa13 ];
    blocklistedLicenses = with lib.licenses; [ gpl3Only gpl3Plus ];
  }
```

--------------------------------

### Example patchShebangs usage

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Examples of using patchShebangs with host and build flags.

```bash
patchShebangs --host /nix/store/<hash>-hello-1.0/bin
```

```bash
patchShebangs --build configure
```

--------------------------------

### Viewing nix-prefetch-docker help

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Display the help menu for the nix-prefetch-docker utility to see all supported arguments.

```bash
$ nix run nixpkgs#nix-prefetch-docker -- --help
(output removed for clarity)
```

--------------------------------

### Configure install targets

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Specifies custom make targets for the installation phase.

```nix
{ installTargets = "install-bin install-doc"; }
```

--------------------------------

### Usage examples for lib.fixedPoints.fix

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Examples showing fix applied to attribute sets and lists.

```nix
fix (self: { foo = "foo"; bar = "bar"; foobar = self.foo + self.bar; })
=> { bar = "bar"; foo = "foo"; foobar = "foobar"; }

fix (self: [ 1 2 (elemAt self 0 + elemAt self 1) ])
=> [ 1 2 3 ]
```

--------------------------------

### Build and run a Docker image with nix-build

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Demonstrates the workflow of building a Docker image using nix-build, loading it into Docker, and starting a shell container.

```bash
$ nix-build
(some output removed for clarity)
/nix/store/rpf47f4z5b9qr4db4ach9yr4b85hjhxq-env-helpers.tar.gz
$ docker image load -i /nix/store/rpf47f4z5b9qr4db4ach9yr4b85hjhxq-env-helpers.tar.gz
(output removed for clarity)
$ docker container run --rm -it env-helpers:latest /bin/sh
sh-5.2# help
GNU bash, version 5.2.21(1)-release (x86_64-pc-linux-gnu)
(rest of output removed for clarity)
```

--------------------------------

### lib.fixedPoints.fix Usage Examples

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Examples comparing recursive attribute sets with let-binding recursion.

```nix
nix-repl> rec {
  foo = "foo";
  bar = "bar";
  foobar = foo + bar;
}
{ bar = "bar"; foo = "foo"; foobar = "foobar"; }
```

```nix
nix-repl> let self = {
  foo = "foo";
  bar = "bar";
  foobar = self.foo + self.bar;
}; in self
{ bar = "bar"; foo = "foo"; foobar = "foobar"; }
```

--------------------------------

### Install an Octave package

Source: https://nixos.org/manual/nixpkgs/unstable

Install an Octave package into the user profile from the repository root.

```bash
$ nix-env -f. -iA octavePackages.symbolic
```

--------------------------------

### Install Manpage with Custom Name

Source: https://nixos.org/manual/nixpkgs/unstable

Installs a manpage file using a specific name.

```nix
postInstall = ''
    installManPage -- --name
  '';
}
```

--------------------------------

### Building the exportImage package

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example output showing the unpacking process during a nix-build of the exportImage function.

```bash
$ nix-build
(some output removed for clarity)
Unpacking base image...
From-image name or tag wasn't set. Reading the first ID.
Unpacking layer 5731199219418f175d1580dbca05677e69144425b2d9ecb60f416cd57ca3ca42/layer.tar
tar: Removing leading `/' from member names
Unpacking layer e2897bf34bb78c4a65736510204282d9f7ca258ba048c183d665bd0f3d24c5ec/layer.tar
tar: Removing leading `/' from member names
Unpacking layer 420aa5876dca4128cd5256da7dea0948e30ef5971712f82601718cdb0a6b4cda/layer.tar
tar: Removing leading `/' from member names
Unpacking layer ea5f4e620e7906c8ecbc506b5e6f46420e68d4b842c3303260d5eb621b5942e5/layer.tar
tar: Removing leading `/' from member names
Unpacking layer 65807b9abe8ab753fa97da8fb74a21fcd4725cc51e1b679c7973c97acd47ebcf/layer.tar
tar: Removing leading `/' from member names
Unpacking layer b7da2076b60ebc0ea6824ef641978332b8ac908d47b2d07ff31b9cc362245605/layer.tar
Executing post-mount steps...
Packing raw image...
[    1.660036] reboot: Power down
/nix/store/x6a5m7c6zdpqz1d8j7cnzpx9glzzvd2h-hello
```

--------------------------------

### Profiling configuration overlay start

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Initial boilerplate for configuring global profiling settings via Nixpkgs overlays.

```nix
let
```

--------------------------------

### Install nix-generate-from-cpan

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Command to install the utility for generating Nix expressions from CPAN modules.

```bash
$ nix-env -f "<nixpkgs>" -iA nix-generate-from-cpan
```

--------------------------------

### Enter nix-shell with Idris libraries

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Start a shell environment with specific Idris libraries available.

```bash
$ nix-shell -p 'idrisPackages.with-packages (with idrisPackages; [ contrib pruviloj ])'
```

--------------------------------

### Install custom Idris package

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Install the custom Idris package defined in an overlay.

```bash
$ # On NixOS
$ nix-env -iA nixos.myIdris
$ # On non-NixOS
$ nix-env -iA nixpkgs.myIdris
```

--------------------------------

### Define meta.teams default and example

Source: https://nixos.org/manual/nixpkgs/unstable

Default value and example usage for the meta.teams attribute set.

```nix
[ ]
```

```nix
[ lib.teams.acme lib.teams.haskell ]
```

--------------------------------

### Build a Docker image using runAsRoot

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Demonstrates using runAsRoot to perform filesystem operations during the image build process.

```nix
{
  dockerTools,
  buildEnv,
  hello,
}:
dockerTools.buildImage {
  name = "hello";
  tag = "latest";

  copyToRoot = buildEnv {
    name = "image-root";
    paths = [ hello ];
    pathsToLink = [ "/bin" ];
  };

  runAsRoot = ''
    mkdir -p /data
    echo "some content" > my-file
  '';

  config = {
    Cmd = [ "/bin/hello" ];
    WorkingDir = "/data";
  };
}
```

--------------------------------

### Initialize Dotnet development environment

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Command to enter a nix-shell for Dotnet development.

```bash
nix-shell -p dotnet-sdk
```

--------------------------------

### Define meta.maintainers default and example

Source: https://nixos.org/manual/nixpkgs/unstable

Default value and example usage for the meta.maintainers attribute set.

```nix
[ ]
```

```nix
[ lib.maintainers.alice lib.maintainers.bob ]
```

--------------------------------

### Configure Project References

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example configuration for adding project and package references within a .NET project file.

```xml
    <ProjectReference Include="../foo/bar.fsproj" />
    <PackageReference Include="bar" Version="*" Condition=" '$(ContinuousIntegrationBuild)'=='true' "/>
```

--------------------------------

### CPE Example for glibc

Source: https://nixos.org/manual/nixpkgs/unstable

A concrete example of a CPE 2.3 string for glibc version 2.40.1.

```text
cpe:2.3:a:gnu:glibc:2.40.1:*:*:*:*:*:*:*
```

--------------------------------

### Build and verify fetchurl output

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Shows how to trigger the download using nix-build and verify the resulting file content.

```bash
$ nix-build
(output removed for clarity)
/nix/store/4g9y3x851wqrvim4zcz5x2v3zivmsq8n-version

$ cat /nix/store/4g9y3x851wqrvim4zcz5x2v3zivmsq8n-version
23.11
```

--------------------------------

### Define a .NET Application Package

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example default.nix file demonstrating the use of buildDotnetModule with various configuration arguments.

```nix
{
  lib,
  buildDotnetModule,
  dotnetCorePackages,
  ffmpeg,
}:

let
  referencedProject = import ../../bar {
    # ...
  };
in
buildDotnetModule rec {
  pname = "someDotnetApplication";
  version = "0.1";

  src = ./.;

  projectFile = "src/project.sln";
  nugetDeps = ./deps.json; # see "Generating and updating NuGet dependencies" section for details

  buildInputs = [
    referencedProject
  ]; # `referencedProject` must contain `nupkg` in the folder structure.

  dotnet-sdk = dotnetCorePackages.sdk_8_0;
  dotnet-runtime = dotnetCorePackages.runtime_8_0;

  executables = [ "foo" ]; # This wraps "$out/lib/$pname/foo" to `$out/bin/foo`.
  executables = [ ]; # Don't install any executables.

  packNupkg = true; # This packs the project as "foo-0.1.nupkg" at `$out/share`.

  runtimeDeps = [ ffmpeg ]; # This will wrap ffmpeg's library path into `LD_LIBRARY_PATH`.
}
```

--------------------------------

### Install custom environment to profile

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Command to build and install the defined environment into the user profile.

```bash
nix-env -iA myEnv
```

--------------------------------

### Add build phase hooks

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Demonstrates using preConfigure to generate files before the build script runs.

```nix
(hello { }).override {
  preConfigure = ''
    echo "pub const PATH=\"${hi.out}\";" >> src/path.rs"
  '';
}
```

--------------------------------

### Define Go build tags

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Examples of setting static and conditional build tags for Go projects.

```nix
{
  tags = [
    "production"
    "sqlite"
  ];
}
```

```nix
{ tags = [ "production" ] ++ lib.optionals withSqlite [ "sqlite" ]; }
```

--------------------------------

### Build and Install Octave Packages

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Commands to build or install Octave packages from the Nixpkgs repository.

```bash
$ nix-build -A octavePackages.symbolic
```

```bash
$ nix-env -f. -iA octavePackages.symbolic
```

--------------------------------

### Install Idris via nix-env

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Install the base Idris compiler using the nix-env command.

```bash
$ nix-env -f "<nixpkgs>" -iA idris
```

--------------------------------

### Include documentation outputs in environment

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Configure extraOutputsToInstall to ensure documentation files like man pages are included in the build environment.

```nix
{
  packageOverrides =
    pkgs: with pkgs; {
      myPackages = pkgs.buildEnv {
        name = "my-packages";
        paths = [
          aspell
          bc
          coreutils
          ffmpeg
          nix
          emscripten
          jq
          nox
          silver-searcher
        ];
        pathsToLink = [
          "/share/man"
          "/share/doc"
          "/bin"
        ];
        extraOutputsToInstall = [
          "man"
          "doc"
        ];
      };
    };
}
```

--------------------------------

### Join subpaths usage example

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example of joining multiple subpath strings into a single normalized path.

```nix
subpath.join [ "foo" "bar/baz" ]
=> "./foo/bar/baz"
```

--------------------------------

### Create a desktop file with makeDesktopItem

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Demonstrates the configuration of various XDG specification fields, including actions and extra configuration, to generate a desktop file.

```nix
{ makeDesktopItem }:
makeDesktopItem {
  name = "my-program";
  desktopName = "My Program";
  genericName = "Video Player";
  noDisplay = false;
  comment = "Cool video player";
  icon = "/path/to/icon";
  onlyShowIn = [ "KDE" ];
  dbusActivatable = true;
  tryExec = "my-program";
  exec = "my-program --someflag";
  path = "/some/working/path";
  terminal = false;
  actions.example = {
    name = "New Window";
    exec = "my-program --new-window";
    icon = "/some/icon";
  };
  mimeTypes = [ "video/mp4" ];
  categories = [ "Utility" ];
  implements = [ "org.my-program" ];
  keywords = [
    "Video"
    "Player"
  ];
  startupNotify = false;
  startupWMClass = "MyProgram";
  prefersNonDefaultGPU = false;
  extraConfig.X-SomeExtension = "somevalue";
}
```

--------------------------------

### Configuring pnpm install flags

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Passing additional flags to the pnpm install process via pnpmInstallFlags.

```nix
{
  # ...
  pnpmDeps = fetchPnpmDeps {
    # ...
    inherit (finalAttrs) pnpmInstallFlags;
  };

  pnpmInstallFlags = [ "--shamefully-hoist" ];
}
```

--------------------------------

### Manage plugins with Vim packages

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Define start and optional plugins within a package set using the native Vim package manager.

```nix
vim-full.customize {
  vimrcConfig.packages.myVimPackage = with pkgs.vimPlugins; {
    # loaded on launch
    start = [
      youcompleteme
      fugitive
    ];
    # manually loadable by calling `:packadd $plugin-name`
    # however, if a Vim plugin has a dependency that is not explicitly listed in
    # opt that dependency will always be added to start to avoid confusion.
    opt = [
      phpCompletion
      elm-vim
    ];
    # To automatically load a plugin when opening a filetype, add vimrc lines like:
    # autocmd FileType php :packadd phpCompletion
  };
}
```

--------------------------------

### Create custom Emacs configuration file

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Inject a default.el configuration file into the Emacs site-start directory to automate package setup.

```nix
{
  packageOverrides = pkgs: {
    myEmacsConfig = pkgs.writeText "default.el" ''
      (eval-when-compile
        (require 'use-package))

      ;; load some packages

      (use-package company
        :bind ("<C-tab>" . company-complete)
        :diminish company-mode
        :commands (company-mode global-company-mode)
        :defer 1
        :config
        (global-company-mode))

      (use-package counsel
        :commands (counsel-descbinds)
        :bind (([remap execute-extended-command] . counsel-M-x)
               ("C-x C-f" . counsel-find-file)
               ("C-c g" . counsel-git)
               ("C-c j" . counsel-git-grep)
               ("C-c k" . counsel-ag)
               ("C-x l" . counsel-locate)
               ("M-y" . counsel-yank-pop)))

      (use-package flycheck
        :defer 2
        :config (global-flycheck-mode))

      (use-package ivy
        :defer 1
        :bind (("C-c C-r" . ivy-resume)
               ("C-x C-b" . ivy-switch-buffer)
               :map ivy-minibuffer-map
               ("C-j" . ivy-call))
        :diminish ivy-mode
        :commands ivy-mode
        :config
        (ivy-mode 1))

      (use-package magit
        :defer
        :if (executable-find "git")
        :bind (("C-x g" . magit-status)
               ("C-x G" . magit-dispatch-popup))
        :init
        (setq magit-completing-read-function 'ivy-completing-read))

      (use-package projectile
        :commands projectile-mode
        :bind-keymap ("C-c p" . projectile-command-map)
        :defer 5
        :config
        (projectile-global-mode))
    '';

    myEmacs = emacs.pkgs.withPackages (
      epkgs:
      (with epkgs.melpaStablePackages; [
        (runCommand "default.el" { } ''
          mkdir -p $out/share/emacs/site-lisp
          cp ${myEmacsConfig} $out/share/emacs/site-lisp/default.el
        '')
        company
        counsel
        flycheck
        ivy
        magit
        projectile
        use-package
      ])
    );
  };
}
```

--------------------------------

### Install Cataclysm DDA via Nix

Source: https://nixos.org/manual/nixpkgs/unstable

Commands to install stable or curses-only builds of Cataclysm DDA to your profile.

```bash
nix-env -f "<nixpkgs>" -iA cataclysm-dda
```

```bash
cataclysmDDA.stable.curses
```

--------------------------------

### Build and use Common Lisp wrappers

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Create a shell environment with specific packages and load them using the Nixpkgs-provided ASDF.

```bash
nix-shell -p 'sbcl.withPackages (ps: [ ps.alexandria ps.bordeaux-threads ])'
```

```lisp
$ sbcl
* (load (sb-ext:posix-getenv "ASDF"))
* (asdf:load-system 'alexandria)
* (asdf:load-system 'bordeaux-threads)
```

--------------------------------

### Build a D package with buildDubPackage

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example configuration for building a D project using the Dub package manager.

```nix
{
  lib,
  buildDubPackage,
  fetchFromGitHub,
  ncurses,
  zlib,
}:

buildDubPackage rec {
  pname = "btdu";
  version = "0.5.1";

  src = fetchFromGitHub {
    owner = "CyberShadow";
    repo = "btdu";
    tag = "v${version}";
    hash = "sha256-3sSZq+5UJH02IO0Y1yL3BLHDb4lk8k6awb5ZysBQciE=";
  };
```

--------------------------------

### Install Hy with Python Packages

Source: https://nixos.org/manual/nixpkgs/unstable

Install Hy with custom Python packages using nix-shell or by extending configuration.nix.

```bash
$ nix-shell -p "hy.withPackages (ps: with ps; [ numpy matplotlib ])"
```

```nix
{

```

--------------------------------

### Run binary with qemu

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Execute a cross-compiled binary using qemu in a nix-shell.

```bash
$ nix-shell -p qemu --run 'qemu-aarch64 ./result/bin/hello'
Hello, world!
```

--------------------------------

### Install standalone Treesitter parsers

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Use this approach to install grammars and queries without the full nvim-treesitter plugin.

```nix
(pkgs.neovim.override {
  configure = {
    packages.myPlugins =
      with pkgs.vimPlugins;
      let
        # Select the grammars you need
        treesitter-grammars = with nvim-treesitter-parsers; [
          nix
          python
        ];
        # Queries are needed for treesitter based syntax highlighting and folds.
        treesitter-queries = map (p: p.associatedQuery) treesitter-grammars;
      in
      {
        start = [
          # regular plugins
        ]
        ++ treesitter-grammars
        ++ treesitter-queries;
      };
  };
})
```

--------------------------------

### Install Custom Font Formats

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Uses the installFont function to install specific font formats like SVG.

```nix
{
  nativeBuildInputs = [ installFonts ];

  postInstall = ''
    installFont svg $out/share/fonts/svg
  '';
}
```

--------------------------------

### Run an OCI container with runc

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Demonstrates building the container package and executing it using the runc runtime.

```bash
$ nix-build
(some output removed for clarity)
/nix/store/7f9hgx0arvhzp2a3qphp28rxbn748l25-join

$ cd /nix/store/7f9hgx0arvhzp2a3qphp28rxbn748l25-join
$ nix-shell -p runc
[nix-shell:/nix/store/7f9hgx0arvhzp2a3qphp28rxbn748l25-join]$ sudo runc run ocitools-example
help
GNU bash, version 5.2.26(1)-release (x86_64-pc-linux-gnu)
(some output removed for clarity)
```

--------------------------------

### Build and run Docker image

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Commands to build the image with nix-build, load it into Docker, and execute a shell.

```bash
$ nix-build
(some output removed for clarity)
/nix/store/2p0i3i04cgjlk71hsn7ll4kxaxxiv4qg-docker-image-env-helpers.tar.gz
$ docker image load -i /nix/store/2p0i3i04cgjlk71hsn7ll4kxaxxiv4qg-docker-image-env-helpers.tar.gz
(output removed for clarity)
$ docker container run --rm -it env-helpers:latest /bin/sh
sh-5.2# help
GNU bash, version 5.2.21(1)-release (x86_64-pc-linux-gnu)
(rest of output removed for clarity)
```

--------------------------------

### PIC hardening error example

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example of an assembler error occurring when position independent code is enabled in an incompatible environment.

```text
ccbLfRgg.s: Assembler messages:
ccbLfRgg.s:33: Error: missing or invalid displacement expression `private_key_len@GOTOFF'
```

--------------------------------

### Enter a Haskell Development Environment

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Shows how to use nix-shell to enter an environment pre-configured with package dependencies.

```bash
$ cd ~/src/random
$ nix-shell -A haskellPackages.random.env '<nixpkgs>'
[nix-shell:~/src/random]$ ghc-pkg list
/nix/store/a8hhl54xlzfizrhcf03c1l3f6l9l8qwv-ghc-9.2.4-with-packages/lib/ghc-9.2.4/package.conf.d
    Cabal-3.6.3.0
    array-0.5.4.0
    base-4.16.3.0
    binary-0.8.9.0
    …
    ghc-9.2.4
    …
```

--------------------------------

### Build a Dart application with buildDartApplication

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example derivation for building a Dart application using fetchFromGitHub and a pre-imported pubspec.lock.json file.

```nix
{
  lib,
  buildDartApplication,
  fetchFromGitHub,
}:

buildDartApplication (finalAttrs: {
  pname = "dart-sass";
  version = "1.62.1";

  src = fetchFromGitHub {
    owner = "sass";
    repo = "dart-sass";
    tag = finalAttrs.version;
    hash = "sha256-U6enz8yJcc4Wf8m54eYIAnVg/jsGi247Wy8lp1r1wg4=";
  };

  pubspecLock = lib.importJSON ./pubspec.lock.json;
})
```

--------------------------------

### Format hardening error example

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example of a build error caused by the format hardening flag when a format string is not a literal.

```text
/tmp/nix-build-zynaddsubfx-2.5.2.drv-0/zynaddsubfx-2.5.2/src/UI/guimain.cpp:571:28: error: format not a string literal and no format arguments [-Werror=format-security]
         printf(help_message);
                            ^
cc1plus: some warnings being treated as errors
```

--------------------------------

### Build a Nim package with buildNimPackage

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Example of a Nim program build configuration using a lockfile and buildNimPackage.

```nix
{
  lib,
  buildNimPackage,
  fetchFromGitHub,
}:

buildNimPackage (finalAttrs: {
  pname = "ttop";
  version = "1.2.7";

  src = fetchFromGitHub {
    owner = "inv2004";
    repo = "ttop";
    tag = "v${finalAttrs.version}";
    hash = lib.fakeHash;
  };

  lockFile = ./lock.json;

  nimFlags = [ "-d:NimblePkgVersion=${finalAttrs.version}" ];
})
```

--------------------------------

### Configure a development environment with shellFor

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

An example of using shellFor to create a development environment that includes multiple packages and their dependencies.

```nix
{
  pkgs ? import <nixpkgs> { },
}:

pkgs.haskellPackages.shellFor {
  packages = hpkgs: [
    # reuse the nixpkgs for this package
    hpkgs.distribution-nixpkgs
    # call our generated Nix expression manually
    (hpkgs.callPackage ./my-project/my-project.nix { })
  ];
```

--------------------------------

### Configure Idris2 prefix for installation

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Set IDRIS2_PREFIX to a writable directory to allow running idris2 --install successfully.

```nix
{
  pkgs ? import <nixpkgs> { },
}:
pkgs.mkShell {
  packages = [ (idris2.withPackages (p: [ p.idris2Api ])) ];
  shellHook = ''
    IDRIS2_PREFIX="$HOME/.idris2"
  '';
}
```

--------------------------------

### Create a custom Python environment

Source: https://nixos.org/manual/nixpkgs/unstable/#javascript-buildNpmPackage

Demonstrates how to define a custom package within a let expression and include it in a Python environment using withPackages.

```nix
with import <nixpkgs> { };

(
  let
    my_toolz = python313Packages.buildPythonPackage (finalAttrs: {
      pname = "toolz";
      version = "0.10.0";
      pyproject = true;

      src = fetchPypi {
        inherit (finalAttrs) pname version;
        hash = "sha256-CP3V73yWSArRHBLUct4hrNMjWZlvaaUlkpm1QP66RWA=";
      };

      build-system = [ python313Packages.setuptools ];

      # has no tests
      doCheck = false;

      meta = {
        homepage = "https://github.com/pytoolz/toolz/";
        description = "List processing tools and functional utilities";
        # [...]
      };
    });

  in
  python313Packages.python.withPackages (
    ps: with ps; [
      numpy
      my_toolz
    ]
  )
).env
```