##记得切换到root用户执行升级操作.

[root@centos ~]# uname -a ##旧版

Linux centos 2.6.32-642.el6.x86_64 #1 SMP Tue May 10 17:27:01 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

[root@localhost ~]# rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org

[root@centos ~]# rpm -ivh http://www.elrepo.org/elrepo-release-6-8.el6.elrepo.noarch.rpm

Retrieving http://www.elrepo.org/elrepo-release-6-8.el6.elrepo.noarch.rpm

Preparing... ########################################### [100%]

1:elrepo-release ########################################### [100%]

[root@localhost ~]# yum --enablerepo=elrepo-kernel install kernel-lt -y ##此步会有点慢

[root@localhost ~]# vim /etc/grub.conf default=1 改为 default=0 ##设置默认以3.10核心启动，默认是按照旧的核心启动

[root@localhost ~]# reboot

[root@centos ~]# uname -a ##升级后的版本

Linux centos 4.4.131-1.el6.elrepo.x86_64 #1 SMP Wed May 2 14:51:15 EDT 2018 x86_64 x86_64 x86_64 GNU/Linux