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

[root@localhost ~]# yum makecache

Loaded plugins: fastestmirror, refresh-packagekit, security

Existing lock /var/run/yum.pid: another copy is running as pid 2542.

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

在更换yum源的过程中出现这个报错，可能是系统自动升级正在运行，yum在锁定状态。

[root@localhost ~]# ps -aux | grep yum

Warning: bad syntax, perhaps a bogus '-'? See /usr/share/doc/procps-3.2.8/FAQ

root       2542  0.0  0.0      0     0 ?        Z    22:18   0:01 [yumBackend.py] <defunct>

root      23606  0.0  0.0 103244   836 pts/1    S+   23:55   0:00 grep yum

在这时使用kill并不能生效

这是可以强制关闭yum里的进程

[root@localhost ~]# rm -f /var/run/yum.pid

这时继续执行就可以了。