I messed up and tried adding a grub menu entry to shutdown the computer using the "halt" command. I accidentally put the "halt" command outside the menu entry 'tags' and now the computer starts to boot and after post immediately shuts down again. From my understanding what is happening is grub is booting and running the script with my shutdown menu entry and just running the halt command as it is outside the menu entry tags. I have managed to boot the computer to a Ubuntu live USB and found what I thought was the script but after removing the command outside the tags and restarting the computer it shuts down like before. How can I edit or remove the menu entry while booted off the USB?
How to edit or remove a grub menu entry while booted off a live usb
bootdual-bootgrub2shutdownuefi
Related Solutions
Each time you upgrade kernel on external, you can run this to update boot stanza in grub on the internal drive.
sudo update-grub
But you can also add a boot stanza to grub2's 40_custom that boots the partition, not the specific kernel. Ubuntu installs links in / (root) to boot the most recent install. Adjust example below if necessary to your drive & partition. Boot drive with grub is always hd0, but then other drives are in BIOS reported order which may vary.
Edit with:
gksudo gedit /etc/grub.d/40_custom
then, add:
menuentry "Install on sdb1" {
set root=(hd1,1)
linux /vmlinuz root=/dev/sdb1 ro quiet splash
initrd /initrd.img
}
While above works, I find the drive may change when plugging in a flash drive or any other USB device. So I am converting to use labels.
menuentry "Cosmic 18.10 on sdb12 test" {
search --set=root --label cosmic_b --hint hd2,gpt12
configfile /boot/grub/grub.cfg
}
Re-install Grub
sudo grub-install path/to/root/disk
Grub auto-detects operative systems during installation. I think it will also detect outside the disk you install it on, Like if you have a Live USB plugged that is not the booted system it will include it too.
I have mine in /dev/sda
sudo grub-install /dev/sda
Open Disks app and look for the partition that shows (Bootable):
Best Answer
these are the steps:
Hope it is more clear now.
Again, good luck.