[Express] express:command not found after installation with npm

Today I’ve tried to install Express with npm, the first time, I have got this problem :

express1

I solved this problem by adding a “sudo”, simple ? And I try to type “express” in the terminal.What’

ZUT! I got this : express: command not found

What’s wrong? After a little search, I found the command :

Type the command :

sudo npm install -g express-generator@3

And it works !