[root@lamp02 yum.repos.d]# yum install nfs-utils rpcbind -y
Loaded plugins: fastestmirror, security
Existing lock /var/run/yum.pid: another copy is running as pid 3517.
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: yum
Memory : 24 M RSS (856 MB VSZ)
Started: Sun Dec 2 14:22:30 2018 - 10:05 ago
State : Traced/Stopped, pid: 3517
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: yum
Memory : 24 M RSS (856 MB VSZ)
Started: Sun Dec 2 14:22:30 2018 - 10:07 ago
State : Traced/Stopped, pid: 3517
在yum使用过程中，有时会出现Loaded plugins错误，重启无效，经过百度发现只要删除/var/run/yum.pid就可以正常使用了，即rm -rf /var/run/yum.pid。
具体命令如下：
rm -rf /var/run/yum.pid
/sbin/service yum-updatesd restart