another app is currently holding the yum lock;waiting for it to exit解决有时用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...可以通过以下命令强制关掉yum进程：
# rm -f /var/run/yum.pid然后就可以使用yum了。
done！
