another app is currently holding the yum lock;waiting for it to exit

another app is currently holding the yum lock;waiting for it to exit...

有时用yum升级一些文件时，会出现以下情况：
another app is currently holding the yum lock;waiting for it to exit...
可以通过强制关掉yum进程：
#rm -f /var/run/yum.pid
然后就可以使用yum了。