Probelms with Serial Console

Bill MacAllister bill at
Thu May 25 04:03:37 CEST 2017

I am having several problems that I could use some help with.

First, I don't seem to be able to configure serial consoles on the physical 
systems I am building. I am building Xenial systems from a stretch nfsroot. 
I have a very small script that tries to update grub, but it keeps failing.

#! /bin/bash
# support for GRUB version 2

error=0; trap 'error=$(($?>$error?$?:$error))' ERR # save maximum error 

set -vx

# skip the rest, if not an initial installation
if [ "$FAI_ACTION" != "install" ]; then
    exit $error

echo 'GRUB_CMDLINE_LINUX_DEFAULT=""'      >> $target/etc/default/grub
echo 'GRUB_CMDLINE_LINUX="console=ttyS0"' >> $target/etc/default/grub

$ROOTCMD update-grub

exit $error

I have determined that the update-grub command is what is failing. I have 
tried lots of variations on that command line to no avail.  What am I 

I probably could figure this out if I was getting logs off of the machine, 
but just setting LOGUSER is not cutting it because ssh is failing. Sitting 
here thinking about it I am guessing that I need to create a key pair in 
/root of the nfsroot and then put the public key in the user's account.  
That is what I will try next, but if I have it wrong I would appreciate a 

Thanks in advance,


"Can't sing louder than the guns when I'm gone,
so I guess I'll have to do it while I'm here."

Phil Ochs

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