refactor: rename shell script templates

bash/script/nixpkgs/flake.nix

@@ -0,0 +1,17 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    systems.url = "github:nix-systems/default";
+  };
+
+  outputs = { self, nixpkgs, systems, ... }:
+    let eachSystem = nixpkgs.lib.genAttrs (import systems);
+    in {
+      packages = eachSystem (system:
+        let pkgs = nixpkgs.legacyPackages.${system};
+        in {
+          hello = pkgs.callPackage ./package.nix {};
+          default = self.packages.${system}.hello;
+        });
+    };
+}

bash/script/nixpkgs/hello

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+echo "Hello, World!"

bash/script/nixpkgs/package.nix

@@ -0,0 +1,17 @@
+{ stdenvNoCC
+, bash
+}:
+
+stdenvNoCC.mkDerivation {
+  pname = "hello";
+  version = "0.1";
+
+  src = ./.;
+
+  buildInputs = [ bash ];
+
+  installPhase = ''
+    mkdir -p $out/bin
+    cp hello $out/bin
+  '';
+}