一、在yum安装或者升级的过程中可能会遇到这个问题
Could not open/read file:///etc/pki/rpm-gpg/RPM-GPG-KEY-puias
参看这个网页里面的（http://linuxsysconfig.com/2013/03/running-multiple-python-versions-on-centos6rhel6sl6/）：
download and import the rpm gpg key
cd /etc/pki/rpm-gpg/ wget http://springdale.math.ias.edu/data/puias/6/x86_64/os/RPM-GPG-KEY-puias rpm --import RPM-GPG-KEY-puias
即可。
二、如果出现GPG key retrieval failed: [Errno 14] Could not open/read file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6问题，请在线安装epel，
yum install http://mirrors.sohu.com/fedora-epel/6/x86_64/epel-release-6-8.noarch.rpm
这一步执行之后，会在/etc/yum.repos.d/下生成epel.repo、epel-testing.repo两个文件，用于从Fedora官网下载rpm包。
本文转自 转身撞墙角 51CTO博客，原文链接:http://blog.51cto.com/chentianwang/1711348
