从FC18到FC19之后，yum安装或者升级软件出现Couldn't open file /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-x86_6错误
ln -s /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-19-primary /etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-x86_64
或者
yum --nogpgcheck