yum安装方法
安装过程中用到的类库：
ncurses-5.5-24.20060715.i386.rpm
compat-readline43-4.3-3.i386.rpm
expat-1.95.8-11.el5_8.i386.rpm
wget?http://yum.baseurl.org/download/3.2/yum-3.2.28.tar.gz
tar xvf yum-3.2.28.tar.gz?
cd yum-3.2.28
yummain.py install?yum?
yum check-update
yum update
yum clean all
