1.查看安装的内核版本
awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg
0 : Red Hat Enterprise Linux Server (5.14.2-1.el7.elrepo.x86_64) 7.2 (Maipo)
1 : Red Hat Enterprise Linux Server (5.12.8-1.el7.elrepo.x86_64) 7.2 (Maipo)
2 : Red Hat Enterprise Linux Server (5.4.144-1.el7.elrepo.x86_64) 7.2 (Maipo)
3 : Red Hat Enterprise Linux Server (3.10.0-1160.42.2.el7.x86_64) 7.2 (Maipo)
4 : Red Hat Enterprise Linux Server (3.10.0-327.el7.x86_64) 7.2 (Maipo)
5 : Red Hat Enterprise Linux Server (0-rescue-47c97cd002da4da8bd5d6bfc6d9c454d) 7.2 (Maipo)
6 : Red Hat Enterprise Linux Server release 7.2 (Maipo) (on /dev/sdb3)
2.修改版本配置
vi /etc/default/grub
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
#GRUB_DEFAULT=saved
GRUB_DEFAULT=3
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap net.ifnames=0 biosdevname=0 rhgb quiet"
GRUB_DISABLE_RECOVERY="true"
GRUB_DEFAULT的值改为上面查看的对应值，这里要改为 3.10.0-1160.42.2.el7.x86_64则修改为：
GRUB_DEFAULT=3
3.编译配置
grub2-mkconfig -o /boot/grub2/grub.cfg
4.重启系统
reboot
5.重启后查看内核版本
uname -a
完成版本切换