今天在linux中使用yum时出现如下错误：
Loaded plugins: fastestmirror, security
Existing lock /var/run/yum.pid: another copy is running as pid 4733.
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: yum-updatesd-he
Memory : 22 M RSS (249 MB VSZ)
Started: Fri Jul 6 12:18:29 2012 - 53:47 ago
State : Sleeping, pid: 4733
关机重启后也没有解决，后尝试删除yum.pid文件，并重启yum服务后OK，具体命令如下：
rm -rf /var/run/yum.pid
/sbin/service yum-updatesd restart