centos升级内核到最新

yum -y install https://www.elrepo.org/elrepo-release-7.0-4.el7.elrepo.noarch.rpm
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
yum --enablerepo=elrepo-kernel install -y kernel-lt

yum -y --enablerepo=elrepo-kernel install kernel-lt-{devel,headers,perf}
# 失败则加   --skip-broken 


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

#看数字
grub2-set-default 2
grub2-mkconfig -o /etc/grub2.cfg
reboot