There are no kernels in the Grub2 menu during the reboot

Issue

There are no kernels in the Grub2 menu during the reboot

One can see only one option in the following output:

# awk -F\' '$1=="menuentry " {print i++ " = "$2}' /etc/grub2.cfg
0 = CloudLinux

Environment

• CloudLinux OS 6/7/8

Solution

1. Check the /etc/default/grub file:

# cat /etc/default/grub 

GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_ENABLE_BLSCFG=true
GRUB_DISABLE_SUBMENU=false
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=auto net.ifnames=0 biosdevname=0 rootflags=usrquota,grpquota,prjquota"
GRUB_DISABLE_RECOVERY="false"

2. Set the GRUB_DISABLE_SUBMENU option to true.

3. Apply the changes:

grub2-mkconfig -o /etc/grub2.cfg
grub2-mkconfig -o /etc/grub2-efi.cfg
grub2-mkconfig -o /boot/grub2/grub.cfg
grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg
grub2-mkconfig -o /boot/efi/EFI/almalinux/grub.cfg

Cause

Grub2 submenu is enabled in a configuration file.