Check NetworkManager is DHCP or Static with command line Ubuntu

Question

How can I check the GUI network setting is set DHCP or Static with command line? for the active and connected interface in Ubuntu 18.04

I want one line command like grep give me static/dhcp or true/false

Answer 1

Can use ip command to check interface you're interested in.

E.g. to check the interface eth0:

if ip -6 addr show eth0  | grep -q dynamic; then
    echo "Uses DHCP addressing"
else
    echo "Uses static addressing"
fi

-6 option is for checking IPv6 interface. You can use -4 for IPv4.