Issue: After you install express-generator on your Ubuntu machine and try to run it like

express -h

You may encounter an error saying "/usr/bin/env: node: No such file or directory"

Solution: The issue is that the Node executable for Ubuntu is nodejs instead of node. So to get around this situation, we can create a symbolic link for nodejs and name it "node". 

which nodejs
sudo ln -s /usr/bin/nodejs /usr/bin/node

First command will tell you where, iin your system "nodejs" is and where you need to create that symbolic link. The second command actually creates the link. In this command change the path i.e. "/usr/bin" to suit your need.