#baseurl=http://mirrors.sohu.com/centos/$releasever/addons/$basearch/
#gpgcheck=1
#gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5CentOS-Base-sohu.repo
然后，再执行yum makecache。之后，yum就可以找到我要安装的包了，比如gdb, subversion, gcc-c++ 等。
注意：
有时用yum list xxx找不到某个包，可用尝试用yum search xxx。
如，yum list vim 就报告 Error: No matching Packages to list。而 yum search vim 则返回：
vim-X11.x86_64 : The VIM version of the vi editor for the X Window System
vim-common.x86_64 : The common files needed by any version of the VIM editor
vim-enhanced.x86_64 : A version of the VIM editor which includes recent enhancements
vim-minimal.x86_64 : A minimal version of the VIM editor
