Estou no Linux Ubuntu 16.04 Rodei os comandos sudo apt-get install -y nodejs, depois nodejs server e já gerou erro:
module.js:328
    throw err;
    ^
Error: Cannot find module 'express'
    at Function.Module._resolveFilename (module.js:326:15)
    at Function.Module._load (module.js:277:25)
    at Module.require (module.js:354:17)
    at require (internal/module.js:12:17)
    at Object.<anonymous> (/var/www/html/alurapic/config/express.js:1:77)
    at Module._compile (module.js:410:26)
    at Object.Module._extensions..js (module.js:417:10)
    at Module.load (module.js:344:32)
    at Function.Module._load (module.js:301:12)
    at Module.require (module.js:354:17)
O que pode ser?