just installed new ubuntu vm to test around with node installed things in this order:
node
mongodb-server
npm
express
mongoose
now, trying
EDIT 2017-06-29: this answer is 6+ years old, but still gets votes/traffic. Instead (for any new users with problems) I'd trust both NODE_PATH official doc and its corresponding bit about REPL usage before this answer.
Quite similar to this issue, node was not finding my global express install, so a require('express')
statement would fail.
What fixed this for me, when a global install wasn't being picked up by node was making sure NODE_PATH
env. variable was is set correctly.
On Ubuntu 11.04, with node version 0.5.0-pre, the paths me were:
NODE_PATH=/usr/local/lib/node_modules:/usr/local/lib/node
So, to clarify you might want to export the above env. variable, or you can just test the above values out by doing:
NODE_PATH=/usr/local/lib/node_modules:/usr/local/lib/node node ./you_app.js