$ [sudo] npm i -g mac-screensaver-cli

$ [sudo] pip install mac-screensaver-cli

usage: screensaver command [args]

Available commands:
    start      start ScreenSaver
    pid        ScreenSaverEngine.app pid
    stop       stop ScreenSaver

    name       current screensaver name
    names      screensaver names


run `screensaver COMMAND --help` for more infos

$ screensaver start # start default screensaver
$ screensaver start "Flurry" # start screensaver by name
$ screensaver stop