How to find the IPv6 delegated prefix from the command line

[rocketraman]

The web interface shows the "IPv6 delegated prefix" value in the Interfaces/Overview under the WAN interface. How can I obtain this information from a shell?

The `ifconfig` command shows the delegated prefix under my LAN interface but with the wrong prefix length: /64 instead of /56 which shows on the web interface.

[rocketraman]

Figured out one way to do it:

cat $(ifctl -6 -l -p)