npm 経由で scripts のコマンドを実行すると $(npm bin) が PATH に追加されるらしい

% cd /tmp/
% npm init
This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sane defaults.

See `npm help json` for definitive documentation on these fields
and exactly what they do.

Use `npm install <pkg> --save` afterwards to install a package and
save it as a dependency in the package.json file.

Press ^C at any time to quit.
name: (tmp)
version: (0.0.0)
description:
entry point: (index.js)
test command: echo $PATH
git repository:
keywords:
author:
license: (ISC)
About to write to /private/tmp/package.json:

{
  "name": "tmp",
  "version": "0.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo $PATH"
  },
  "author": "",
  "license": "ISC"
}


Is this ok? (yes) yes
% npm test | sed "s|$HOME|\$HOME|g"

> tmp@0.0.0 test /private/tmp
> echo $PATH

/usr/local/Cellar/node/0.10.24/lib/node_modules/npm/bin/node-gyp-bin:/private/tmp/node_modules/.bin:/usr/local/Cellar/node/0.10.24/bin:$HOME/.rbenv/shims:$HOME/local/bin:/usr/local/share/npm/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin
% echo $PATH | sed "s|$HOME|\$HOME|g"
$HOME/.rbenv/shims:$HOME/local/bin:/usr/local/share/npm/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin