CentOS7.3升级到CentOS7.9

1）查看当前centos系统版本和内核版本

[root@centos7-82 ~]# cat /etc/redhat-release
CentOS Linux release 7.3.1611 (Core)

2）备份原来的CentOS-Base.repo

[root@centos7-82 ~]# cd /etc/yum.repos.d/

[root@centos7-82 yum.repos.d]# cp CentOS-Base.repo CentOS-Base.repo_bak

3）修改yum源。

要保证更换的yum源地址可以正常访问。如下使用阿里云的yum源http://mirrors.aliyun.com/centos/7.9.2009，要保证手动打开这个地址是有效地址，且镜像yum源内容完整存在。

[base]

name=CentOS-$releasever

enabled=1

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos/7.9.2009/os/$basearch/

gpgcheck=1

gpgkey=http://mirrors.cloud.aliyuncs.com/centos/RPM-GPG-KEY-CentOS-7

[updates]

name=CentOS-$releasever

enabled=1

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos/7.9.2009/updates/$basearch/

gpgcheck=1

gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

[extras]

name=CentOS-$releasever

enabled=1

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos/7.9.2009/extras/$basearch/

gpgcheck=1

gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

4）执行更新yum

确保下面更新操作没有报错。

[root@centos7-82  yum.repos.d]# yum update -y

5）重启系统

[root@centos7-82  yum.repos.d]# init 6

重启后查看系统版本

[root@centos7-82 yum.repos.d]# cat /etc/redhat-release
CentOS Linux release 7.9.2009 (Core)