用法：
yum --disablerepo=reponame # 禁用源
yum --enablerepo=reponame # 啓用源
# 以使用本地yum源安裝php爲例
# 查看可用的源
[test@localhost ~]$ yum repolist
Loaded plugins: fastestmirror, security
Determining fastest mirrors
.....省略....
repo id repo name status
base CentOS-6 - Base 6,696
c6-media CentOS-6 - Media 6,575
extras CentOS-6 - Extras 60
updates CentOS-6 - Updates 94
repolist: 13,425
# 只是用本地yum源來安裝
[test@localhost etc]$ sudo yum --disablerepo='*' --enablerepo=c6-media install php
Loaded plugins: fastestmirror, security
Setting up Install Process
Loading mirror speeds from cached hostfile
* c6-media: <--------注意
Resolving Dependencies
--> Running transaction check
# 以上還可寫作
[test@localhost etc]$ sudo yum --disablerepo=* --enablerepo=c6-media install php
Loaded plugins: fastestmirror, security
Setting up Install Process
Loading mirror speeds from cached hostfile
* c6-media: <--------注意與之前輸出的區別
Resolving Dependencies
--> Running transaction check
# 除了指定的源，其他存在的源也會啓用
[test@localhost etc]$ sudo yum --enablerepo=c6-media install php
[sudo] password for test:
Loaded plugins: fastestmirror, security
Setting up Install Process
Loading mirror speeds from cached hostfile
* base: mirrors.yun-idc.com <------注意與之前輸出的區別
* c6-media:
* extras: mirrors.yun-idc.com
* updates: mirrors.yun-idc.com
Resolving Dependencies
--> Running transaction check
# 所有的源都被禁用
[test@localhost etc]$ sudo yum --disablerepo='*' install php
Loaded plugins: fastestmirror, security
Setting up Install Process
Loading mirror speeds from cached hostfile
No package php available. <------注意與之前輸出的區別
Error: Nothing to do