Chrome and Firefox have the ability to take screenshots of web sites directly from the command line. This allows you to create scripts or scheduled tasks that automatically take screenshots at various intervals. Using this feature, the browsers will be started in a headless mode, which means the browser will not become visible to the user and will close after performing the desired request. Chrome will only take a screenshot of a portion of the requested web page using the –headless –screenshot=”d:testchrome.png”” “”https://www.bleepingcomputer.com/”””
Source: https://www.bleepingcomputer.com/news/software/chrome-and-firefox-can-take-screenshots-of-sites-from-the-command-line/