爱华网1)切换成 root 用户：
# su -
2)为fedora.repo、fedora-updates.repo 加 .bak 后缀：
#mv fedora.repo.bak
#mv fedora-updates.repo.bak
2.再在 /etc/yum.repos.d/目录下创建 fedora-ustc.repo 和 fedora-updates-ustc.repo两个文件：
fedora-ustc.repo文件内容如下：
[fedora]
name=Fedora$releasever - $basearch - ustc
failovermethod=priority
baseurl=http://mirrors.ustc.edu.cn/fedora/linux/releases/$releasever/Everything/$basearch/os/
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=fedora-$releasever&arch=$basearch
enabled=1
metadata_expire=7d
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
[fedora-debuginfo]
name=Fedora$releasever - $basearch - Debug - ustc
failovermethod=priority
baseurl=http://mirrors.ustc.edu.cn/fedora/linux/releases/$releasever/Everything/$basearch/debug/
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=fedora-debug-$releasever&arch=$basearch
enabled=0
metadata_expire=7d
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
[fedora-source]
name=Fedora$releasever - Source - ustc
failovermethod=priority
baseurl=http://mirrors.ustc.edu.cn/fedora/linux/releases/$releasever/Everything/source/SRPMS/
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=fedora-source-$releasever&arch=$basearch
enabled=0
metadata_expire=7d
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
fedora-updates-ustc.repo文件内容如下：
[updates]
name=Fedora$releasever - $basearch - Updates - ustc
failovermethod=priority
baseurl=http://mirrors.ustc.edu.cn/fedora/linux/updates/$releasever/$basearch/
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=updates-released-f$releasever&arch=$basearch
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
[updates-debuginfo]
name=Fedora$releasever - $basearch - Updates - Debug-ustc
failovermethod=priority
baseurl=http://mirrors.ustc.edu.cn/fedora/linux/updates/$releasever/$basearch/debug/
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=updates-released-debug-f$releasever&arch=$basearch
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
[updates-source]
name=Fedora$releasever - Updates Source - ustc
failovermethod=priority
baseurl=http://mirrors.ustc.edu.cn/fedora/linux/updates/$releasever/SRPMS/
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=updates-released-source-f$releasever&arch=$basearch
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
3.清除原有信息，再生成缓存：
# yum cleanall
# yummakecache
