node main.js Error

[ipnet@rocketchat opt]$ node main.js
module.js:540
    throw err;
    ^

Error: Cannot find module '/opt/main.js'
    at Function.Module._resolveFilename (module.js:538:15)
    at Function.Module._load (module.js:468:25)
    at Function.Module.runMain (module.js:684:10)
    at startup (bootstrap_node.js:187:16)
    at bootstrap_node.js:608:3
