如何在CentOS Enterprise Linux服务器5.x或者RHEL 5.x系统下使用yum命令下载RPM软件包？

您需要安装名为yum-downloadonly的插件。
该插件向yum添加了一个downloadonly标志，因此yum将仅下载软件包，而不安装/更新它们。
该插件支持以下选项：

• downloadonly：不更新，仅下载rpm文件
• downloaddir =/path/to/dir：指定备用目录来存储软件包，例如/tmp

请注意，以下说明仅在CentOS服务器上经过测试，但可以与RHN和RHEL一起使用而没有任何问题。

如何安装yum-downloadonly插件？

输入以下命令以安装插件，执行：

# yum install yum-downloadonly

输出示例：

Loading "fastestmirror" plugin
Loading "security" plugin
Loading mirror speeds from cached hostfile
* base: centos.mirrors.tds.net
* updates: mirror.myriadnetwork.com
* addons: mirrors.gigenet.com
* extras: holmes.umflint.edu
Setting up Install Process
Parsing package install arguments
Resolving Dependencies
--> Running transaction check
---> Package yum-downloadonly.noarch 0:1.1.10-9.el5.centos set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================
Package                 Arch       Version          Repository        Size 
=============================================================================
Installing:
yum-downloadonly        noarch     1.1.10-9.el5.centos  base              9.0 k

Transaction Summary
=============================================================================
Install      1 Package(s)         
Update       0 Package(s)         
Remove       0 Package(s)         

Total download size: 9.0 k
Is this ok [y/N]: y
Downloading Packages:
(1/1): yum-downloadonly-1 100% |=========================| 9.0 kB    00:00     
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing: yum-downloadonly             ######################### [1/1] 

Installed: yum-downloadonly.noarch 0:1.1.10-9.el5.centos
Complete!

如何仅从RHN或者CentOS镜像下载RPM软件包而不安装？

下载httpd软件包，但不要安装/更新，请执行：

# yum update httpd -y --downloadonly

默认情况下，软件包将通过下载并存储在/var/cache/yum /目录中。
但是，您可以指定一个备用目录来存储诸如/opt之类的软件包，执行：

# yum update httpd -y --downloadonly --downloaddir=/opt

输出示例：

yum install httpd -y --downloadonly 
Loading "downloadonly" plugin
Loading "fastestmirror" plugin
Loading "security" plugin
Loading mirror speeds from cached hostfile
* base: centos.mirrors.mypsh.com
* updates: mirror.steadfast.net
* addons: mirrors.gigenet.com
* extras: holmes.umflint.edu
Setting up Install Process
Parsing package install arguments
Resolving Dependencies
--> Running transaction check
---> Package httpd.i386 0:2.2.3-11.el5_1.centos.3 set to be updated
filelists.xml.gz          100% |=========================| 2.8 MB    00:03     
filelists.xml.gz          100% |=========================| 681 kB    00:11     
filelists.xml.gz          100% |=========================| 122 kB    00:00     
filelists.xml.gz          100% |=========================|  150 B    00:00     
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================
Package                 Arch       Version          Repository        Size 
=============================================================================
Installing:
httpd                   i386       2.2.3-11.el5_1.centos.3  base              1.1 M

Transaction Summary
=============================================================================
Install      1 Package(s)         
Update       0 Package(s)         
Remove       0 Package(s)         

Total download size: 1.1 M
Downloading Packages:
(1/1): httpd-2.2.3-11.el5 100% |=========================| 1.1 MB    00:01     

exiting because --downloadonly specified

要查看下载的文件，请执行：

# ls -l /opt/*.rpm

输出示例：

-rw-r--r-- 1 root root 1116426 Jan 17 03:36 /opt/httpd-2.2.3-11.el5_1.centos.3.i386.rpm
-rw-r--r-- 1 root root   83452 Oct  2  2007 /opt/lighttpd-fastcgi-1.4.18-1.el5.rf.i386.rpm
-rw-r--r-- 1 root root  635045 Oct 20  2007 /opt/psad-2.1-1.i386.rpm

方法2：yum-utils.noarch包

yum-utils是yum软件包管理器的实用程序和示例的集合。
它包含不同作者的实用程序，这些实用程序使yum更容易使用，功能更强大。
这些工具包括：debuginfo-install，package-cleanup，repoclosure，repodiff，repo-graph，repomanage，repoquery，repo-rss，reposync，repotrack，verifytree，yum-builddep，yum-complete-transaction，yumdownloader，yum-debug-转储和yum-groups-manager。

# yum -y install yum-utils.noarch

现在使用" yumdownloader命令"，它是一个从Yum存储库下载RPM的程序。
输入以下命令以下载httpd rpm文件：

# yumdownloader httpd

输出示例：

Loaded plugins: rhnplugin
httpd-2.2.3-31.el5_4.2.x86_64.rpm                        | 1.2 MB     00:00

如何提取下载的RPM文件？

执行命令，如下所示：

# rpm2cpio httpd-2.2.3-31.el5_4.2.x86_64.rpm | cpio -idmv