安装YUM

参考：

rpm -qa|grep yum|xargs rpm -e --nodeps  将yum卸载掉

cat /etc/issue && uname -a 看一下系统版本号和系统位数

到  或  找对应系统版本号
如系统是5.5 64位，则打开 找到yum 、yum-fastestmirror、yum-metadata-parser 这3个软件包的地址，然后执行：

wget

wget

wget

#rpm -ivh yum-*

如果是6.*的版本，则将下面内容里面的5改成6后再执行。

cat >/etc/yum.repos.d/CentOS-Base.repo<<eof
[base]
name=CentOS-$releasever - Base
baseurl=http://mirrors.kernel.org/centos/$releasever/os/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5

#released updates
[updates]
name=CentOS-$releasever - Updates
baseurl=http://mirrors.kernel.org/centos/$releasever/updates/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5

#packages used/produced in the build but not released
[addons]
name=CentOS-$releasever - Addons
baseurl=http://mirrors.kernel.org/centos/$releasever/addons/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
baseurl=http://mirrors.kernel.org/centos/$releasever/extras/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
baseurl=http://mirrors.kernel.org/centos/$releasever/centosplus/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5

#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib
baseurl=http://mirrors.kernel.org/centos/$releasever/contrib/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
eof

再执行：yum makecache 生成缓存，再yum install 安装软件试试