問題：運行yun install php -y 出現Existing lock /var/run/yum.pid: another copy is running as pid 12092.問題。
[root@xiao ~]# yum install php -y
Loaded plugins: fastestmirror, refresh-packagekit, security
Existing lock /var/run/yum.pid: another copy is running as pid 12092.
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: yum
Memory : 14 M RSS ( 31 MB VSZ)
Started: Mon Nov 24 02:55:21 2014 - 00:23 ago
State : Sleeping, pid: 12092
原因：安裝的時候yum有一個自動更新的服務（/etc/init.d/yum-updatesd）在運行，激活了yum進程。
方法：停止進程，關閉服務
停止進程：[root@xiao ~]#rm -f /var/run/yum.pid
關閉服務：[root@xiao ~]#/etc/init.d/yum-updatesd stop