Need a way to list all the visible access points, with signal strength and signal quality, on a Ubuntu Linux system?

For a one-shot listing (with color coding):

nmcli d wifi

For ongoing listing:

watch nmcli d wifi

For something fancier:

sudo apt-get install linssid

Yeah, I know about WiFi scanners for Android and iPhone. In this case, I don’t actually need to know the WiFi signals – I need to know how well my Linux system’s WiFi card sees the signals.