fedora 修改yum所有的配置文件，现在用不了。

因为没有备份就 开始配置了。请提供可以用的配置代码，
yum.conf
[main]
cachedir=/var/cache/yum
keepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
metadata_expire=1800
[base]
name=Fedora Core $releasever - $basearch - Base
baseurl=http://mirrors.kernel.org/fedora/core/$releasever/$basearch/os
[updates-released]
name=Fedora Core $releasever - $basearch - Released Updates
baseurl=http://mirrors.kernel.org/fedora/core/updates/$releasever/$basearch
# PUT YOUR REPOS HERE OR IN separate files named file.repo
# in /etc/yum.repos.d

fedora-updates.repo
[updates]

name=Fedora Core $releasever - $basearch - Updates
baseurl=ftp://apt.nc.hcc.edu.tw/pub/fedora/linux/core/updates/$releasever/$basearch/
#baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/updates/$releasever/$basearch/
#mirrorlist=http://fedora.redhat.com/download/mirrors/updates-released-fc$releasever
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora

[updates-debuginfo]
name=Fedora $releasever - $basearch - Updates - Debug
#baseurl=ftp://apt.nc.hcc.edu.tw/pub/fedora/linux/core/updates/$releasever/$basearch/
mirrorlist=ftp://apt.nc.hcc.edu.tw/pub/fedora/linux/core/updates/$releasever/$basearch/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora

[updates-source]
name=Fedora $releasever - Updates Source
#baseurl=ftp://apt.nc.hcc.edu.tw/pub/fedora/linux/core/updates/$releasever/$basearch/
mirrorlist=ftp://apt.nc.hcc.edu.tw/pub/fedora/linux/core/updates/$releasever/$basearch/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora

fedora.repo
[fedora]
name=Fedora $releasever - $basearch
#baseurl=http://ftp.mirror.tw/pub/fedora/linux/releases/$releasever/Everything/$basearch/os/
mirrorlist=ftp://apt.nc.hcc.edu.tw/pub/fedora/linux/core/updates/$releasever/$basearch/
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY

[fedora-debuginfo]
name=Fedora $releasever - $basearch - Debug
#baseurl=http://ftp.mirror.tw/pub/fedora/linux/releases/$releasever/Everything/$basearch/debug/
mirrorlist=ftp://apt.nc.hcc.edu.tw/pub/fedora/linux/core/updates/$releasever/$basearch/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY

[fedora-source]
name=Fedora $releasever - Source
#baseurl=ftp://ftp.mirror.tw/pub/fedora/linux/releases/$releasever/Everything/source/SRPMS/
mirrorlist=ftp://apt.nc.hcc.edu.tw/pub/fedora/linux/core/updates/$releasever/$basearch/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY

好像全部配置都修改成新的源地址。