After waiting several minutes (and believing my machine had stopped) during the 18.04-to-18.10 upgrade process, I hard-booted my machine. Ugh.
Upon restart, the gui fails to display fully... Forcing me to go to tty to attempt continuing the upgrade.
At the commandline, ping fails, letting me know that the network start up had not completed.
My question is: Constrained to a tty, is there a way that I can use a command to get networking active, in hopes that I may continue my upgrade?
More details as I learn them: The upgrade was past the download phase... As the system reports 18.10. It appears to be in a loop... On the GUI screen. It does present a GUI login for my username and password... But, it loops... before I can successfully click my login and enter password, the screen cleats and I see a cursor blinking in top left corner of screen -- no GUI components displaying.
I've successfully logged into TTY.
Ok. I found the boot.log file which indicates (in this order) the following failures: [FAILED] Failed to start CTDB [FAILED] Failed to start LXC network for bridge setup.
And this matches why I'm unable to network...
After reading much about logrotate, journalctl, and boot.log (i.e., my machine is uefi-capable), combined with the previous boot failures, I was able to execute network-manager which connected to my phone via USB (thanks, Kulfy) and I executed apt --fix-broken install.
Linux saves the day, YOA (yet once again).
So, having aborted the upgrade, the GUI screen presented my login screen, but would not wait for me to login. Therefore, I moved into a TTY and connected to my phone as an ethernet connection. Once I manually executed "network-manager" (note, not the same as "NetworkManager" which was either not yet installed or was hiding -- outside of path??), I had a connection to the internet.
and, after some work (on the computer's part; I'm just watching lines scroll!), I'm getting closer and closer to having a usable system. Indeed, this is the first of my messages being typed on affected machine. :)
I'm so happy I moved to Ubuntu all those many, many moons ago.