PDF2XL CLI can be run in Silent Mode, not displaying any user interface while loading a document and converting its contents into one of the target formats.
This is the most 'extreme' form of usage of the Command Line Interface, and can only be started from the command line (or by another application).
When using PDF2XL CLI in Silent Mode, the command line must specify which file to open. It can optionally specify the layout to load, the target format, and the range of pages to convert (if the target format is a file, the command line must specify the file name to write to).
An example of running PDF2XL CLI in Silent Mode from the command line can be viewed in the Command Line Interface Examples.