Ubuntu: Install Kernel and Set GRUB Default Kernel

ubuntu_update_booting_kernel.md

Ubuntu: Install Kernel and Set GRUB Default Kernel

Install Kernel

Install the default kernel:

sudo apt install linux-generic

Set GRUB Default Kernel

1. Find entrance from /boot/grub/grub.cfg
   • Get the $menuentry_id_option:

     grep submenu /boot/grub/grub.cfg

     Example output:

     submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-4591a659-55e2-4bec-8dbe-d98bd9e489cf' {

     'gnulinux-advanced-4591a659-55e2-4bec-8dbe-d98bd9e489cf' is what we need.
   • Get the specific kernel option:

     grep gnulinux-4.15.0 /boot/grub/grub.cfg

     Example output:

     menuentry 'Ubuntu, with Linux 4.15.0-126-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-126-generic-advanced-4591a659-55e2-4bec-8dbe-d98bd9e489cf' {

     'gnulinux-4.15.0-126-generic-advanced-4591a659-55e2-4bec-8dbe-d98bd9e489cf' is what we need.
2. Set GRUB_DEFAULT in /etc/default/grub
   • Join two entry strings obtained above by '>', set to GRUB_DEFAULT.

     GRUB_DEFAULT='gnulinux-advanced-4591a659-55e2-4bec-8dbe-d98bd9e489cf>gnulinux-4.15.0-126-generic-advanced-4591a659-55e2-4bec-8dbe-d98bd9e489cf'

3. Update grub

   sudo update-grub

4. Reboot the machine

you can use this to get the specific kernel you need, assuming is currently in use:

grep gnulinux-$(uname -r) /boot/grub/grub.cfg