注意:Fedora 15 仍处于测试阶段，所以，升级有风险的哦。
Yum update from previous release
This method is available but not recommended for anyone except the bravest testers. Anaconda can make changes that are outside of the ability for the packaging system to handle. You may also run into dependency problems which could take time to resolve. You may also need to upgrade from the immediately previous release (e.g. install Fedora 10, 11, then Fedora 12 Rawhide and not jump directly from Fedora 10 to Fedora 12 Rawhide). Remember that Rawhide installations in general may need to be wiped and re-installed from scratch at any time.
You can upgrade to the rawhide repository one of two ways.
（第一种方法） Using graphical applications:
1，First, install thefedora-release-rawhidepackage:
Click on thebuild status link
Check the latest build on Koji (for instance,fedora-release-14-0.6).
Download the corresponding RPM files (e.g. withwget).
Install the RPM release files:rpm -Uvh fedora-release-*.noarch.rpm.
2，Next, modify your software sources using:gpk-repo
LeaveonlytheFedora – Rawhidesoftware source enabled
3，Next, update your system using:gpk-update-viewer
（第二种方法）Alternatively, you may upgrade using the command-line:
1，Type:yum install fedora-release-rawhide
2，，Then type:yum –disablerepo=* –enablerepo=rawhide update
（ps:我用的是第二种方法）
You may want to enable/disable repositories in /etc/yum.repos.d/ so that only the “Fedora Development” repository is enabled. This will allow daily Rawhide updates to appear by default in desktop notifications and “yum update”.
If you cannot install fedora-release-rawhide from within the package system, you can download the RPM directly from a Rawhide mirror, under:development/rawhide/<arch>/os/Packages/ (for instance: wget*.noarch.rpm)
不论你在什么时候结束，重要的是结束之后就不要悔恨
