By "root console" do you mean root in recovery mode, or as su in a terminal? I went to root in recovery mode, entered the commands as given, and after entering the last command was left with a blinking cursor. I didn't know what to do next. I tried exit, reboot, and finally had to do a Ctrl-Alt-Delete. I went back into recovery mode, selected enable networking, and got the same error message.
Either I didn't do this correctly, or it had no effect on my system.
LATER: It would seem that if the purpose of this is to change the address of my nameserver to 8.8.8.8, then I could do this through Control Center > Network. Going here I notice that the address of my DNS server is 127.0.0.53
and the address for localhost is 127.0.0.1 and for jim-pc is 127.0.1.1.
Could I not change the address here and then I think there's a command to restart the network manager? Here are the contents of /etc/hosts:
Is one of these addresses supposed to be 8.8.8.8?