$ npm install express -g problem

$ npm install express -g

error

Finally find the reason, it turns out that the command tool is separated in the latest express version (project address: https://github.com/expressjs/generator), so we also need to install a command tool, the command is as follows:

npm install -g express-generator

Then in express --version (two -      do not express -v nor do not express -V Baidu tutorial has a problem )