ubuntu boot from particular kernel version

If kernel version to boot from Linux 4.15.0-32-generic

Get menuentries

root@Ubuntu9-141:~# grep -A100 submenu  /boot/grub/grub.cfg |grep menuentry

submenu 'Advanced options for Ubuntu GNU/Linux' $menuentry_id_option 'gnulinux-advanced-b56fcaaa00cf79aa' {

menuentry 'Ubuntu GNU/Linux, with Linux 4.15.0-54-generic' --class Ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-54-generic-advanced-b56fcaaa00cf79aa' {

menuentry 'Ubuntu GNU/Linux, with Linux 4.15.0-54-generic (recovery mode)' --class Ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-54-generic-recovery-b56fcaaa00cf79aa' {

menuentry 'Ubuntu GNU/Linux, with Linux 4.15.0-50-generic' --class Ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-50-generic-advanced-b56fcaaa00cf79aa' {

menuentry 'Ubuntu GNU/Linux, with Linux 4.15.0-50-generic (recovery mode)' --class Ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-50-generic-recovery-b56fcaaa00cf79aa' {

menuentry 'Ubuntu GNU/Linux, with Linux 4.15.0-32-generic' --class Ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-32-generic-advanced-b56fcaaa00cf79aa' {

menuentry 'Ubuntu GNU/Linux, with Linux 4.15.0-32-generic (recovery mode)' --class Ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-4.15.0-32-generic-recovery-b56fcaaa00cf79aa' {

Edit /etc/default/grub

GRUB_DEFAULT='gnulinux-advanced-b56fcaaa00cf79aa>gnulinux-4.15.0-32-generic-advanced-b56fcaaa00cf79aa'

Update grub

root@Ubuntu9-141:~# update-grub

Generating grub configuration file ...

Found linux image: /boot/vmlinuz-4.4.0-59-generic

Found initrd image: /boot/initrd.img-4.4.0-59-generic

Found linux image: /boot/vmlinuz-3.19.0-73-generic

Found initrd image: /boot/initrd.img-3.19.0-73-generic

Found linux image: /boot/vmlinuz-3.19.0-43-generic

Found initrd image: /boot/initrd.img-3.19.0-43-generic

Found memtest86+ image: /memtest86+.elf

Found memtest86+ image: /memtest86+.bin

done

...........

reboot to verify