In order to start an unattended installation, the installer has to be invoked with the -q argument. The installer will be absolutely quiet and will perform the installation as if the user had accepted all default settings. You can change the default selection for all relevant features, e.g. the initial selection of custom and standard tasks, services (install4j Enterprise Edition only), and installation components.
There is no user interaction on the terminal. In all cases, where the installer would have asked the user whether to overwrite an existing file, the installer will not overwrite it. You can change this behavior by passing -overwrite as a parameter to the installer. In this case, the installer will overwrite such files. For the standard case, it is recommended to fine-tune the overwrite policy in the distribution tree instead, so that this situation never arises.
The installer will install the application to the default installation directory, unless you pass the -dir parameter to the installer. The parameter after -dir must be the desired installation dirctory. Example:
installer.exe -q -dir "d:\myapps\My Application"
If the installation was successful, the exit code of the installer will be 0, otherwise it will be 1.