How is use of npm to install global packages that don't even get used in Node applications justified?

Question

My knowledge of npm is this:

It is a package manager for Node.js applications. What this means is that when you need someone else\'s librar

Answer 1

• See @mmocny's answer for why cca is a (global) npm package, despite not containing modules for use in JavaScript code.
• This answer shows how global npm packages work.

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npm packages installed globally, with -g, typically contain executables (whether binary or not) that are to be added to a folder expected to be in your system's $PATH in order to make them globally available in your shell (from the command line) - independently of Node.js.

As npm help folder puts it succinctly (emphasis mine):

• Install it locally if you're going to require() it.
• Install it globally if you're going to run it on the command line.

Global package installation roughly works as follows:

Note: What directory {prefix} represents varies by platform (e.g., /usr on Linux) - you can query its value with npm get prefix or npm prefix -g.
The default Node.js installations on Unix systems install to shared locations, so that root privileges (via sudo) are required for installing packages globally.
By contrast, if you are using Unix-based multi-version managers such as n or nvm, {prefix} may be a user-specific directory such as ~ or ~/.nvm/v0.10.28, so that root privileges are not required for installing packages globally.
The following description is based on Unix platforms, with differing behavior on Windows noted separately, where needed.

• Global packages are installed in a package-specific subfolder of {prefix}/lib/node_modules - e.g., /usr/local/lib/node_modules.

• Symlinks to the executables from the package's bin subfolder (typically; as defined in the "bin" property of the package's package.json file) are then created in {prefix}/bin, e.g., usr/local/bin - which is what makes them globally available, given that {prefix}/bin is assumed to be in the $PATH.

  • Windows: .cmd batch files are used in lieu of symlinks, and they are placed directly in {prefix} (which is added to %PATH% during installation). These batch files are created based on analyzing a given executable's shebang line and explicitly invoke it with the interpreter found there, allowing for a seamless cross-platform experience.

• man pages from the package, if defined, are symlinked to {prefix}/share/man, e.g., /usr/local/share/man

  • Windows: man pages are not installed at all.

See also http://blog.nodejs.org/2011/03/23/npm-1-0-global-vs-local-installation/