执行yum命令时，提示“Another app is currently holding the yum lock; waiting for it to exit...”等错误字样。这是因为yum被锁定无法使用导致的。

错误信息参考：

Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: yum
    Memory :  40 M RSS ( 50 MB VSZ)
    Started: Thu Jul 19 01:59:25 2012 - 03:45 ago
    State  : Uninteruptable, pid: 903

解决方案：

rm -rf /var/run/yum.pid

SSH执行以上命令，删除yum.pid强行解除锁定即可。