Run Unity in batch mode. You should always use this in conjunction with the other command line arguments, because it ensures no pop-up windows appear and eliminates the need for any human intervention. When an exception occurs during execution of the script code, the Asset server updates fail, or other operations fail, Unity immediately exits with return code 1.

Note that in batch mode, Unity sends a minimal version of its log output to the console. However, the Log Files still contain the full log information. You cannot open a project in batch mode while the Editor has the same project open; only a single instance of Unity can run at a time.

Tip: To check whether you are running the Editor or Standalone Player in batch mode, use the Application.isBatchMode operator.