centos7.6升级为7.9版本，谨慎操作

第 1 步备份原 yum 源并切换到阿里云 vaultmkdir -p /etc/yum.repos.d/bak mv /etc/yum.repos.d/*.repo /etc/yum.repos.d/bak/ 2/dev/nullcat /etc/yum.repos.d/CentOS-Vault.repo EOF [base] nameCentOS-7.9.2009 - Base baseurlhttps://mirrors.aliyun.com/centos-vault/7.9.2009/os/$basearch/ gpgcheck1 gpgkeyfile:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7 enabled1 [updates] nameCentOS-7.9.2009 - Updates baseurlhttps://mirrors.aliyun.com/centos-vault/7.9.2009/updates/$basearch/ gpgcheck1 gpgkeyfile:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7 enabled1 [extras] nameCentOS-7.9.2009 - Extras baseurlhttps://mirrors.aliyun.com/centos-vault/7.9.2009/extras/$basearch/ gpgcheck1 gpgkeyfile:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7 enabled1 EOF第 2 步刷新 yum 缓存yum clean all yum makecachecat /etc/centos-release此时应该还是CentOS Linux release 7.6.1810 (Core)正常。第 3 步全量升级含内核yum update -y这一步会下载 300–500MB 的包5–15 分钟中间不要中断。如果担心断网可以加tmux或nohup跑。第 4 步清理并重启yum clean all reboot第 5 步验证升级结果cat /etc/centos-release期望CentOS Linux release 7.9.2009 (Core)