使用kexec来替换新内核

replace-new-kernel.sh

latestkernel=`ls -t /boot/vmlinuz-* | sed "s/\/boot\/vmlinuz-//g" | head -n1`
echo $latestkernel
kexec -l /boot/vmlinuz-${latestkernel} --initrd=/boot/initramfs-${latestkernel}.img --append="`cat /proc/cmdline`"
kexec -e

# 备注，其实和重启没啥两样, uptime也会清零重算，唯一的好处就是比重启要快一点点

# remove old kernels on centos 8
dnf remove --oldinstallonly --setopt installonly_limit=1 kernel