今天在centos6.10上安装软件时报错，之前记得还可以啊，报错信息如下：
[root@localhost build]# yum install gcc-c++
Loaded plugins: fastestmirror, security
Setting up Install Process
Determining fastest mirrors
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
Eg. Invalid release/repo/arch combination/
removing mirrorlist with no valid mirrors: /var/cache/yum/x86_64/6/base/mirrorlist.txt
Error: Cannot find a valid baseurl for repo: base
使用yum update命令也是一样：
[root@localhost build]# yum update
Loaded plugins: fastestmirror, ovl
Setting up Update Process
Loading mirror speeds from cached hostfile
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
Eg. Invalid release/repo/arch combination/
removing mirrorlist with no valid mirrors: /var/cache/yum/x86_64/6/base/mirrorlist.txt
Error: Cannot find a valid baseurl for repo: base看错误提示，似乎是说找不到有效的baseurl。所以要解决这个问题，还要从baseurl着手。
从官方邮件可知，CentOS 6自从2020年11月30日开始，官方不再维护，所以连带着原来的yum存储库也不能用了。
但是邮件里说得很明白，它给出了迁移后的存储库的链接地址，这时候我们只需要更新yum存储库的镜像列表，就可以正常使用了。
步骤如下：
cd /etc/yum.repos.d
cp CentOS-Base.repo CentOS-Base.repo.old
vi CentOS-Base.repo主要修改内容如下：
[base]
name=CentOS-$releasever - Base
# mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
# baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
baseurl=https://vault.centos.org/6.10/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
# released updates
[updates]
name=CentOS-$releasever - Updates
# mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
# baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
baseurl=https://vault.centos.org/6.10/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
# additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
# mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
# baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
baseurl=https://vault.centos.org/6.10/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6再次执行安装命令就可以了
yum install gcc-c++