执行yum出现Loaded plugins: fastestmirror, langpacks Existing lock /var/run/yum.pid: another copy is ...

执行yum install的时候出现：

Loaded plugins: fastestmirror, langpacks
Existing lock /var/run/yum.pid: another copy is running as pid 2847.
Another app is currently holding the yum lock; waiting for it to exit...

yum在锁定状态中。 
已经有一个yum进程在运行了，可以使用kill干掉它：

kill -s 9 2847

如果不可以用kill杀死，可以强制停掉yum

rm -f /var/run/yum.pid