好的,我想通了.我创建了一个文件CentOs.repo(/etc/yum.repos.d/CentOs.repo),其中包含以下内容：
- [CentOS-Base]
- name=CentOS-Base
- mirrorlist=http://mirrorlist.centos.org/?release=5&arch=$basearch&repo=os
- gpgcheck=1
- enabled=1
- gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
- [CentOS-Updates]
- name=CentOS-Updates
- mirrorlist=http://mirrorlist.centos.org/?release=5&arch=$basearch&repo=updates
- gpgcheck=1
- enabled=1
- gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
- [CentOS-Plus]
- name=CentOS-Plus
- mirrorlist=http://mirrorlist.centos.org/?release=5&arch=$basearch&repo=centosplus
- gpgcheck=1
- enabled=1
- gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
