5.更新Fedora yum源
使用yum安装相关软件包时一直提示以下错误：
repodata/repomd.xml:[Errno 4] IOError: <urlopen error (113>，Error:Cannot retrieve repository metadata (repomd.xml) for repository:base. Please verify its path and try again。
这是由于fedora系统找不到yum源所导致的，所以我们需要重新设置yum源。之前自己也看过比较多的人介绍yum源的设置，他们大多都是使用上海交大/163/sohu等的yum源，具体做法是将.repo文件存放到/etc/yum.repos.d目录，然后再运行“yum makecache”即可。但是这种方法我试过很多次，我的系统就是没有反应。原因有二：要么就是yum源有问题;要么就是除了更改/etc/yum.repos.d目录下的.repo文件，还需要修改其他配置文件，这是其他人没有注意到的。事实证明，第一种推测是正确的。用的是中国科学技术大学(ustc)的yum源，具体配置如下：
1.删除/etc/yum.repos.d目录下所有.repo文件
[root@jiangdongguo yum.repos.d]# rm *.repo
2.再/etc/yum.repos.d目录下创建一个fedora.repo文件和fedora_update.repo（可有可无）
[root@jiangdongguo yum.repos.d]# vim fedora.repo
内容：
[fedora]
name=Fedora $releasever - $basearch
failovermethod=priority
baseurl=http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/$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 - $basearch -Debug
failovermethod=priority
baseurl=http:http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/$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 $releasever - Source
failovermethod=priority
baseurl=http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/$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
[root@jiangdongguo yum.repos.d]# vim fedora_update.repo
[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
[[email protected]]#yum clean all
[root@jiangdongguo yum.repos.d]#yum makecache