$ a2marshal --help
usage: a2marshal [-h] [--iface IFACE] [--modem-dev PATH] [--keyboard-dev PATH]
                 [--abdicate CMDLINE]

options:
  -h, --help           show this help message and exit
  --iface IFACE        ifupdown interface name (default: ppp-aero2)
  --modem-dev PATH     run "udevadm trigger" if this device doesn't exist;
                       this might be needed when usb-modeswitch is misbehaving
  --keyboard-dev PATH  use this input device for LED blinking (default:
                       /dev/input/by-path/platform-i8042-serio-0-event-kbd)
  --abdicate CMDLINE   command line for abdicate