[root@localhost CentOS]# mkdir /media/CentOS
把光盘加载到本地
[root@localhost CentOS]# mount /dev/cdrom /media/CentOS
在/etc/yum.repos.d/目录下，有两个文件
CentOS-Base.repo和CentOS-Media.repo
其中CentOS-Base.repo记录着网络上的yum源的地址和路径信息等
CentOS-Media.repo记录着可以从本地作为yum源的介质和路径。其中还有这样一个说明：
# CentOS-Media.repo
#
# This repo is used to mount the default locations for a CDROM / DVD on
# CentOS-5. You can use this repo and yum to install items directly off the
# DVD ISO that we release.
#
# To use this repo, put in your DVD and use it with the other repos too:
# yum --enablerepo=c5-media [command]
#
# or for ONLY the media repo, do this:
#
# yum --disablerepo=\* --enablerepo=c5-media [command]
[c5-media]
name=CentOS-$releasever - Media
baseurl=file:///media/ CentOS
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-beta
我们只需编辑下bashurl ，将自己的光盘路径写入就可以了。
觉得自己的光盘的源足够用了。不需要网络源，或者没有网络。
可以使用yum --disablerepo=\* --enablerepo=c5-media [command]
yum命令允许使用本地media介质的源而已。正确的命令如下（更新gcc为例）：
[root@centos cdrom]# yum --disablerepo =* --enablerepo=c5-media install gcc
Loading " installonlyn " plugin
Setting up Update Process
Setting up repositories
c5 - media 100 % |=========================| 1.1 kB 00 : 00
Reading repository metadata in from local files
primary.xml.gz 100 % |=========================| 834 kB 00 : 00
################################################## 2400 / 2400
No Packages marked for Update / Obsoletion
比如安装gdb
[root@centos cdrom]# yum --disablerepo =* --enablerepo=c5-media install gdb
Loading " installonlyn " plugin
Setting up Install Process
Setting up repositories
Reading repository metadata in from local files
Parsing package install arguments
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Downloading header for gdb to pack into transaction set .
gdb - 6.5 - 25 .el5.i386.rpm 100 % |=========================| 56 kB 00 : 00
---> Package gdb.i386 0 : 6.5 - 25 .el5 set to be updated
--> Running transaction check
Dependencies Resolved
=============================================================================
Package Arch Version Repository Size
=============================================================================
Installing:
gdb i386 6.5 - 25 .el5 c5 - media 3.1 M
Transaction Summary
=============================================================================
Install 1 Package(s)
Update 0 Package(s)
Remove 0 Package(s)
Total download size: 3.1 M
Is this ok [y / N]: y
Downloading Packages:
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
Installing: gdb ######################### [ 1 / 1 ]
Installed: gdb.i386 0 : 6.5 - 25 .el5
Complete !
[root@centos cdrom]#
在使用yum进行install时，经常会出现下面的错误
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID 1ac70ce6
导致安装不能进行。解决方法如下：
[root@localhost CentOS]# rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5
[root@localhost CentOS]# rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-beta