Me, I run rtl-ais to decode AIS messages and send its output to a named pipe which acts as a virtual audio file, then run gnu-ais configured to take the named pipe's contents and send them to
aprs.fi. (I'm using a Nooelec SMArt RTL-SDR USB dongle as my AIS receiver as it has a smaller footprint than most SDR dongles and doesn't cover the other USB ports on my Pi, plus I already had it. I also use the Pi as an APRS digipeater and Igate and needed room for a Digirig Mobile's USB cable to be plugged in.) You can see the results if you zoom in the map to Cebu, central Philippines.