wrap-shell-script

name	wrap-shell-script
description	Convert a shell script into a reproducible Nix package
compatibility	Requires nix
metadata	{"author":"ruinous.ai","version":"1.1","domain":"packaging"}
parameters	{"script_name":{"type":"string","description":"Name for the wrapped script package","required":true,"placeholder":"my-script"},"script_path":{"type":"string","description":"Path to existing script file (or \"inline\" to create new)","required":true,"placeholder":"./scripts/backup.sh"}}

Wrap Shell Script

Convert a shell script into a reproducible Nix package with proper dependency management.

Parameter Handling

If parameters are missing from $ARGUMENTS, use mcp_question to gather them:

mcp_question({
  questions: [
    {
      question: "What should the packaged script be named?",
      header: "Name",
      options: [
        { label: "Enter name...", description: "e.g., my-script (will be the command name)" }
      ]
    },
    {
      question: "Where is the script located?",
      header: "Script Path",
      options: [
        { label: "Enter path...", description: "e.g., ./scripts/backup.sh" },
        { label: "Create inline", description: "I'll provide the script content" }
      ]
    }
  ]
})

Expected $ARGUMENTS format: <script_name> <script_path>

• Example: backup-script ./scripts/backup.sh
• Example: my-tool inline (then provide content)

Steps

1. Create package directory

mkdir -p packages/<script-name>

2. Copy or create the script

cp /path/to/script.sh packages/<script-name>/script.sh

3. Create default.nix

{ lib, stdenv, makeWrapper, bash, coreutils, jq, curl }:

stdenv.mkDerivation rec {
  pname = "script-name";
  version = "1.0.0";

  src = ./.;

  nativeBuildInputs = [ makeWrapper ];
  buildInputs = [ bash ];

  dontBuild = true;

  installPhase = ''
    runHook preInstall

    mkdir -p $out/bin
    cp script.sh $out/bin/${pname}
    chmod +x $out/bin/${pname}

    # Wrap with runtime dependencies
    wrapProgram $out/bin/${pname} \
      --prefix PATH : ${lib.makeBinPath [ coreutils jq curl ]}

    runHook postInstall
  '';

  meta = with lib; {
    description = "Description of what the script does";
    homepage = "https://github.com/user/repo";
    license = licenses.mit;
    maintainers = [ ];
    platforms = platforms.unix;
    mainProgram = "script-name";
  };
}

4. Build and test

nix build .#<script-name>
./result/bin/<script-name> --help

Key Concepts

Dependencies

Type	Purpose	Example
nativeBuildInputs	Build-time tools	makeWrapper
buildInputs	Compile-time libs	bash
Runtime (via wrap)	PATH dependencies	coreutils, jq, curl

wrapProgram Options

wrapProgram $out/bin/${pname} \
  --prefix PATH : ${lib.makeBinPath [ dep1 dep2 ]} \
  --set ENV_VAR "value" \
  --suffix PATH : "/additional/path"

Shebang Patching

If script has hardcoded paths:

patchPhase = ''
  patchShebangs .
'';

Alternative: writeShellApplication

For simpler scripts, use writeShellApplication:

{ writeShellApplication, coreutils, jq }:

writeShellApplication {
  name = "my-script";
  runtimeInputs = [ coreutils jq ];
  text = ''
    echo "Hello, $1!"
    jq --version
  '';
}

Common Dependencies

Need	Package
Basic utils	coreutils
JSON processing	jq
HTTP requests	curl, wget
Text processing	gnused, gawk, gnugrep
Archive handling	gzip, unzip, p7zip
Git operations	git
SSH	openssh

Example

/wrap-shell-script backup-script ./scripts/backup.sh

Verification

# Build
nix build .#<script-name>

# Test execution
./result/bin/<script-name>

# Check dependencies are found
ldd ./result/bin/<script-name>  # (if binary wrapper)