作業系統是centos5.6 x86_64,不同的機器已安裝的包有所區別，關鍵是掌握方法。

1下載yum的rpm安裝包 

2 [[email protected] rpm]# rpm -qa | grep yum   //確定沒有安裝yum的rpm包
3 [[email protected] rpm]# rpm -ivh yum-3.2.22-37.el5.centos.noarch.rpm
error: Failed dependencies:
        yum-fastestmirror is needed by yum-3.2.22-37.el5.centos.noarch
        yum-metadata-parser >= 1.1.0 is needed by yum-3.2.22-37.el5.centos.noarch

需要安裝依賴的包

4 找第一個依賴

 [[email protected] rpm]# wget http://mirror.centos.org/centos/5.7/os/x86_64/CentOS/yum-fastestmirror-1.1.16-16.el5.centos.noarch.rpm

5 安裝時發現依賴於yum，這個問題可以兩個rpm包一起安裝解決，先解決第二個依賴

 [[email protected] rpm]# rpm -ivh yum-fastestmirror-1.1.16-16.el5.centos.noarch.rpm

error: Failed dependencies:
        yum >= 3.0 is needed by yum-fastestmirror-1.1.16-16.el5.centos.noarch

6 先解決第二個依賴

 [[email protected] rpm]# rpm -ivh yum-metadata-parser-1.1.2-3.el5.centos.x86_64.rpm

error: Failed dependencies:
        libxml2.so.2()(64bit) is needed by yum-metadata-parser-1.1.2-3.el5.centos.x86_64

7 發現依賴，下載安裝

 [[email protected] rpm]# wget http://mirror.centos.org/centos/5.7/os/x86_64/CentOS/ libxml2-2.6.26-2.1.12.x86_64.rpm

 [[email protected] rpm]# rpm -ivh libxml2-2.6.26-2.1.12.x86_64.rpm
Preparing...                ########################################### [100%]
   1:libxml2                ########################################### [100%]

8 第二個依賴解決，如果還是缺少包，繼續下載安裝。可以登入http://mirror.centos.org/centos/5.7/os/x86_64/CentOS/ 去找

 [[email protected] rpm]# rpm -ivh yum-metadata-parser-1.1.2-3.el5.centos.x86_64.rpm

Preparing...                ########################################### [100%]
   1:yum-metadata-parser    ########################################### [100%]

9 檢驗一下yum包的依賴情況

 [[email protected] rpm]# rpm -ivh yum-fastestmirror-1.1.16-16.el5.centos.noarch.rpm 

error: Failed dependencies:
        yum >= 3.0 is needed by yum-fastestmirror-1.1.16-16.el5.centos.noarch
[[email protected] rpm]# rpm -ivh yum-3.2.22-37.el5.centos.noarch.rpm
error: Failed dependencies:
        yum-fastestmirror is needed by yum-3.2.22-37.el5.centos.noarch
10  兩個一起安裝，解決
[[email protected] rpm]# rpm -ivh yum-3.2.22-37.el5.centos.noarch.rpm yum-fastestmirror-1.1.16-16.el5.centos.noarch.rpm
Preparing...                ########################################### [100%]
   1:yum-fastestmirror      ########################################### [ 50%]

   2:yum                    ########################################### [100%]

11 有需要可以yum -y update