[CentOS] Fixing grub/shim issue Centos 7

Tue Aug 4 14:14:48 UTC 2020
Lamar Owen <lowen at pari.edu>

On 8/4/20 2:31 AM, lpeci wrote:
> 3) Config network:
>     3.1) # ip addr add X.X.X.X/X dev X
>     3.2) # ip route add default via X.X.X.X    <--- default router
While I appreciate the thoughts behind this step in the instructions, 
and I thank you for the post that will be useful to those running fairly 
traditional servers, there are numerous cases where this simply will not 
work to bring up a network while booted into the rescue mode chroot.  
Not all, and maybe not even most, CentOS machines are traditional 
servers with simple direct ethernet connections that don't require more 
steps.  I can just off the top of my head think of three cases where the 
above won't work:

Case 1: Virtualization host with a bridge on multiple VLANs over a 
bond.  Depending upon the type of bond, it may or may not be possible to 
bring up the host's interface to the network with the commands above.  
More than half of my server machines here fall under this case.

Case 2: workstation with wired network and 802.1x authentication.

Case 3: workstation or laptop with only a wireless interface that 
requires a supplicant to authenticate.  Yes, workstation and laptop 
installs of CentOS do exist and are actively used and are just as 
important to recover as any traditional server.

For my laptop I was able to recover thanks to the 'nmtui' text-mode 
interactive interface to NetworkManager, bringing up any of my WiFi 
SSIDs with authentication; if any of my virtualization hosts had hit 
this problem (none did, interestingly enough) nmtui would have allowed 
me to activate the bridge on the host admin vlan quickly and easily 
from, again, a nice interactive text interface that is dead-simple to 
use quickly and accurately, and where you don't have to do any extra 
steps to get the interface name or any other details; nmtui just takes 
care of it in an intuitive manner.