1 working derivation

为了让derivation两个阶段成功运行，除了必要的三个元素，还需要out path存在
为了构建out path，使用bash脚本来进行构建，通过向derivation函数传递参数args = [ ./builder.sh ]来让builder(bash)运行builder.sh构建脚本
第一个可运行的derivation builder.sh
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declare -xp echo foo > $out
nix repl -f '<nixpkgs>'
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nix-repl> d = derivation { name = "foo"; builder = "${bash}/bin/bash"; args = [ ./builder.sh ]; system = builtins.currentSystem; } nix-repl> :b d
通过nix log /nix/store/gvwysj9dkjjan9hvxfnwq2f97chnz437-foo.drv来查看构建过程中的日志(包含打印出的环境变量) 使用nix derivation show /nix/store/gvwysj9dkjjan9hvxfnwq2f97chnz437-foo.drv查看out path等

第二个derivation 由前一个derivation的日志可知，PATH="/path-not-set"，所以为了构建一个简单的c程序，我们需要将gcc的bin路径加入PATH中对derivation函数来说，所有传给它的键值对(除了部分保留的元素，如args)都会以一定的规则转换成builder的环境变量如derivation { other = ./other.file; some = "some"; }，其中other(转换成复制到/nix/store/中的地址)和some会以环境变量的形式传给builder(多为bash)

源码，作为src环境变量传入

simple.c

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void main() {
        puts("Simple!");
}

作为args参数传入，是builder(bash)的参数 (bash simple-builder.sh)

simple-builder.sh

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export PATH="$coreutils/bin/:$gcc/bin"
mkdir $out
gcc -o $out/simple $src

调用derivation求值，并构建

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nix-repl> d = derivation { name = "simple"; builder = "{bash}/bin/bash"; system = builtins.currentSystem; args = [ ./builder.sh ]; src = ./simple.c; inhert (pkgs) gcc coreutils; }
nix-repl> :b d

运行 /nix/store/5hykxkxc8rj9c0q5p19fmagk5ms2rczx-simple/simple

用.nix文件而不是nix repl确保reproducible simple.nix

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let 
  pkgs = import <nixpkgs> { };
in
  derivation {
    name = "simple";
    builder = "${pkgs.bash}/bin/bash";
    system = builtins.currentSystem;
    args = [ ./simple-builder.sh ];
    inherit (pkgs) gcc coreutils;
    src = ./simple.c;
  }

使用nix build --file ./simple.nix 或者 nix-build ./simple.nix来求值并构建该derivation (注：nix-build实际上做了两件事， nix-instantiate和nix-sotre -r)

目录

1 working derivation

源码，作为src环境变量传入

作为args参数传入，是builder(bash)的参数 (bash simple-builder.sh)

调用derivation求值， 并构建

调用derivation求值，并构建