Ubuntu – How to remove an old OS entry from grub

I know you posted this back in May, but I found some stuff that might help anyone looking at this article. I have the same exact problem, and I have not found a true fix for my symptoms yet, but I figured I would post some of my findings.

First, the trick with running some apt-get updates can be found here:link.

I modified mine a bit based on some other articles I read, and also because I encountered one error message with the cp command while trying to copy:

(This is assuming you did the first two steps from the link above and are running from a Live CD that you booted from)

sudo mkdir /media/precise
sudo mkdir /media/precise/proc /media/precise/dev /media/precise/etc
sudo mount /dev/sda1 /media/precise
sudo mount -o bind /proc /media/precise/proc
sudo mount -o bind /dev /media/precise/dev/
sudo mount -o bind /dev/pts /media/precise/dev/pts
sudo cp --remove-destination /etc/resolv.conf /media/precise/etc/resolv.conf
sudo chroot /media/precise apt-get update
sudo chroot /media/precise apt-get upgrade
sudo chroot /media/precise apt-get update --fix-missing
sudo chroot /media/precise dpkg --configure -a
sudo chroot /media/precise dpkg-reconfigure keyboard-configuration
sudo chroot /media/precise apt-get -f install

The reason I had to add the --remove-destination is because I was getting an error message that read something to the effect of: cp: not writing through dangling symlink path/to/danling/symlink/a-file (found the solution for that here: force cp to copy on dangling symlinks)

Secondly, it wasn't until the OS booted that the problem presented itself (hence why the Live Disk worked just fine). So, choosing different option in Grub was possible. I had gone back by two kernels and still had the problem.

Finally, while working on it with someone else at work, he had looked the computer the day before, and said that he booted back several kernels and got into command line, but not GUI. This was a great start because I had an Apache Web Server I needed to get up and available for people again ASAP. So, right now, the machine is running on an old kernel with a broken GUI but apparently working CLI and I am not sure what to do next. Try to remove the kernel? Remove and reinstall X? Not totally sure, but at least its a start, and maybe the link and code I listed above will be a fix for someone else with this problem.

Actually, there are two files that need to be modified to solve this problem. I've tested this on my Lubuntu 16.04.1 and Manjaro Linux.

In Ubuntu:

1) File /usr/lib/linux-boot-probes/mounted/40grub2 there is a function parse_grub_menu that doesn't handle all initrd parameters. You need to modify 'case "$1" in ... initrd)':

a) remove assignment

initrd="$(echo "$2" ...)"

b) add two lines in place of the removed one:

shift 1
initrd="$(echo "$@" | sed 's/(.*)//')"

2) File /etc/grub.d/30_os-prober within a for loop fix the assignment of LINITRD:

for LINUX in ${LINUXPROBED}; do
...
    LINITRD="`echo ${LINUX} | cut -d ':' -f 5 | tr '^' ' '`"

The first fix takes all available initrd info for Manjaro into account. The second fix cleans up the generated initrd line by changing some '^' characters to spaces.