Nix: runCommand, writeShellApplication

README.md

Check nixpkgs/pkgs/build-support/trivial-builders.nix for more information about:

• runCommand / runCommandCC
• writeTextFile / writeTextDir
• writeScript / writeScriptBin
• writeShellScript / writeshellScriptBin
• writeShellApplication
• ...

default.nix

# cat $(nix-build)/bin/date/today.txt
{ nixpkgs ? import <nixpkgs> {}}:

nixpkgs.runCommand "print-date" {
  nativeBuildInputs = [ nixpkgs.coreutils ];
} ''
    # line 5 in nix file = line 1 in bash script -> offset 4
    PS4='+ Line $(expr $LINENO + 4): '
    set -o xtrace # print commands
    mkdir -p $out/date/
    date > $out/date/today.txt
    set +o xtrace # hide commands
''

default2.nix

# $(nix-build)/bin/test
# cat response.json
{ nixpkgs ? import <nixpkgs> {}}:

nixpkgs.writeShellApplication {
  name = "test";
  runtimeInputs = with nixpkgs; [ curl w3m ];
  text = ''
    curl -XPOST httpbin.org/post > response.json
  '';
}