Error installing zmq Node Module - node.js

Question

When installing the zmq node module, I get the following error.
I have the latest stable version of node installed.
I am running a Mac on OS X 10.9.3
npm http GET https://registry.npmjs.org/zmq
npm http 304 https://registry.npmjs.org/zmq
npm http GET https://registry.npmjs.org/nan
npm http GET https://registry.npmjs.org/bindings
npm http 304 https://registry.npmjs.org/nan
npm http 304 https://registry.npmjs.org/bindings
> zmq#2.7.0 install /Users/mario/node_modules/zmq
> node-gyp rebuild
/bin/sh: pkg-config: command not found
gyp: Call to 'pkg-config libzmq --libs' returned exit status 127. while trying to load binding.gyp
gyp ERR! configure error
gyp ERR! stack Error: `gyp` failed with exit code: 1
gyp ERR! stack at ChildProcess.onCpExit (/usr/local/lib/node_modules/npm/node_modules/node-gyp/lib/configure.js:340:16)
gyp ERR! stack at ChildProcess.emit (events.js:98:17)
gyp ERR! stack at Process.ChildProcess._handle.onexit (child_process.js:809:12)
gyp ERR! System Darwin 13.2.0
gyp ERR! command "node" "/usr/local/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
gyp ERR! cwd /Users/mario/node_modules/zmq
gyp ERR! node -v v0.10.29
gyp ERR! node-gyp -v v0.13.0
gyp ERR! not ok
npm ERR! zmq#2.7.0 install: `node-gyp rebuild`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the zmq#2.7.0 install script.
npm ERR! This is most likely a problem with the zmq package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! node-gyp rebuild
npm ERR! You can get their info via:
npm ERR! npm owner ls zmq
npm ERR! There is likely additional logging output above.
npm ERR! System Darwin 13.2.0
npm ERR! command "/usr/local/bin/node" "/usr/local/bin/npm" "install" "zmq"
npm ERR! cwd /Users/mario/messaging
npm ERR! node -v v0.10.29
npm ERR! npm -v 1.4.9
npm ERR! code ELIFECYCLE
npm ERR!
npm ERR! Additional logging details can be found in:
npm ERR! /Users/mario/messaging/npm-debug.log
npm ERR! not ok code 0
Why do I get this error and what should I do to fix it?

Answer 1

Looks like you need to install pkg-config:
/bin/sh: pkg-config: command not found
Try brew install pkg-config