内核升级
<p>内核升级后，设置内核启动顺序步骤：</p>
<h3>1、查看设备上安装了几个内核</h3>
<p>cat /boot/grub2/grub.cfg |grep menuentry</p>
<h3>2、查看当前内核</h3>
<p>grub2-editenv list</p>
<h3>3、修改默认启动的内核</h3>
<p>grub2-set-default 'CentOS Linux (4.15.15-1.el7.elrepo.x86_64) 7 (Core)'</p>
<h1>worker节点升级CentOS7系统，并设置内核为5.5.1</h1>
<pre><code class="language-bash">#!/bin/bash
yum -y update
startuname=`cat /boot/grub2/grub.cfg |grep menuentry |grep 5.5 |awk -F &quot;'&quot; '{print $2}'`
grub2-set-default '$startuname'
reboot</code></pre>
<h1>另一种方法</h1>
<pre><code>[root@worker03 ~]#cat /boot/grub2/grub.cfg |grep menuentry
if [ x&quot;${feature_menuentry_id}&quot; = xy ]; then
menuentry_id_option=&quot;--id&quot;
menuentry_id_option=&quot;&quot;
export menuentry_id_option
menuentry 'CentOS Linux (3.10.0-1160.76.1.el7.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-1160.el7.x86_64-advanced-09a6900f-aaa3-49e3-beca-4826d573ea1b' {
menuentry 'CentOS Linux (5.5.11-1.el7.elrepo.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-1160.el7.x86_64-advanced-09a6900f-aaa3-49e3-beca-4826d573ea1b' {
menuentry 'CentOS Linux (3.10.0-1160.el7.x86_64) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-1160.el7.x86_64-advanced-09a6900f-aaa3-49e3-beca-4826d573ea1b' {
menuentry 'CentOS Linux (0-rescue-5411791349d54954a035bc94729a9bf8) 7 (Core)' --class centos --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-0-rescue-5411791349d54954a035bc94729a9bf8-advanced-09a6900f-aaa3-49e3-beca-4826d573ea1b' {</code></pre>
<h2>根据上面导出结果显示的的id，确定第几个ID值的内容确实第几个</h2>
<pre><code>grub2-set-default 1</code></pre>
<p>数字从 0 开始，即：第一个为 0；</p>
<h1>附，操作命令</h1>
<pre><code>查看/boot分区
df -H /boot
查看内核
rpm -qa|grep kernel
查看当前在用的内核
uname -r
删除不用的内核，一般会保留3个内核，多出来的会删除
rpm -e kernel-3.10.0-1160.el7.x86_64
安装新内核
rpm -ivh kernel-ml-5.5.11-1.el7.elrepo.x86_64.rpm
查看内核排序
cat /boot/grub2/grub.cfg |grep menuentry
确定使用哪个内核
grub2-set-default 0
第一个ID是从0开始
</code></pre>