今天在玩CentOS的時候出現了：
Error: cannot find a valid baseurl for repo: rpmfusion-free
這個問題真到好惡心啊，以前一直使用到是ubuntu，最近切換到CentOS以后，各自小白啊。最后搜索到到答案是：
You seem to have added the RPM Fusion repository incorrectly. Let's start clean. First remove the repo with:
rpm -e rpmfusion-free-release
Then re-enable it using:
rpm -Uvh http://download1.rpmfusion.org/free/el/updates/6/i386/rpmfusion-free-release-6-1.noarch.rpm