Change default kernel on CentOS7

This is how to change the kernel in CentOS7

1. Check kernel version

   uname -r
   

2. Kernel install with yum package manager

   yum install yum-plugin-fastermirror - y
   rpm —import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
   # available kernel list
   yum list available --disablerepo='*' --enablerepo=elrepo-kernel
   # stable kernel
   yum --enablerepo=elrepo-kernel install kernel-lt -y
   # latest kernel
   yum --enablerepo=elrepo-kernel install kernel-ml -y
   

3. Update grub

   # bootable installed kernel check
   awk -F\' '$1=="menuentry " {print $2}' /etc/grub2.cfg
      
   # First is 0, set the desired order
   grub2-set-default 3
   grub2-mkconfig -o /boot/grub2/grub.cfg
      
   # Check the currently set value
   grub2-editenv list
   

4. Reboot

   reboot