在Fedora里执行：
$sudo yum update
Loaded plugins: langpacks, presto, refresh-packagekit
Adding en_US to language list
Error: Cannot retrieve repository metadata (repomd.xml) for repository: fedora. Please verify its path and try again
会出现上面的问题是因为：
从Fedroa21开始，http://mirrors.xxx.com/fedora/releases里面出现了一个README文件提示：
ATTENTION
======================================
The contents of this directory have been moved to our archives available at:
http://archives.fedoraproject.org/pub/archive/fedora/
If you are having troubles finding something there please stop by #fedora-admin on irc.freenode.net
按照这个提示需要将系统默认的repo修改为：
$vi sudo vi /etc/yum.repos.d/fedora.repo
[fedora]
name=Fedora $releasever - $basearch
failovermethod=priority
baseurl=http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/$releasever/Everything/$basearch/os/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
[fedora-debuginfo]
name=Fedora $releasever - $basearch - Debug
failovermethod=priority
baseurl=http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/$releasever/Everything/$basearch/debug/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
[fedora-source]
name=Fedora $releasever - Source
failovermethod=priority
baseurl=http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/$releasever/Everything/source/SRPMS/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
$vi sudo vi /etc/yum.repos.d/fedora.repo
[updates]
name=Fedora $releasever - $basearch - Updates
failovermethod=priority
baseurl=http://archives.fedoraproject.org/pub/archive/fedora/linux/updates/$releasever/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
[updates-debuginfo]
name=Fedora $releasever - $basearch - Updates - Debug
failovermethod=priority
baseurl=http://archives.fedoraproject.org/pub/archive/fedora/linux/updates/$releasever/$basearch/debug/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
[updates-source]
name=Fedora $releasever - Updates Source
failovermethod=priority
baseurl=http://archives.fedoraproject.org/pub/archive/fedora/linux/updates/$releasever/SRPMS/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$basearch
然后执行：
$sudo yum clean all
$sudo yum makecache
[root@localhost yum.repos.d]# yum clean all
Loaded plugins: langpacks, presto, refresh-packagekit
Adding en_US to language list
Cleaning repos: updates
Cleaning up Everything
0 delta-package files removed, by presto
[root@localhost yum.repos.d]# yum makecache
Loaded plugins: langpacks, presto, refresh-packagekit
Adding en_US to language list
updates | 4.7 kB 00:00
updates/filelists_db | 9.4 MB 00:34
updates/prestodelta | 1.0 MB 00:03
updates/primary_db | 5.4 MB 00:19
updates/other_db | 3.1 MB 00:11
updates/group_gz | 420 kB 00:01
updates/updateinfo | 767 kB 00:02
Metadata Cache Created
