[root@linuxprobe Desktop]# yum install elinks
Loaded plugins: fastestmirror, langpacks
Existing lock /var/run/yum.pid: another copy is running as pid 3972.
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: PackageKit
Memory : 40 M RSS (920 MB VSZ)
Started: Sun Oct 16 12:01:11 2016 - 01:07 ago
State : Sleeping, pid: 3972
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: PackageKit
Memory : 40 M RSS (920 MB VSZ)
Started: Sun Oct 16 12:01:11 2016 - 01:09 ago
State : Running, pid: 3972
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: PackageKit
Memory : 40 M RSS (920 MB VSZ)
Started: Sun Oct 16 12:01:11 2016 - 01:11 ago
State : Running, pid: 3972
Another app is currently holding the yum lock; waiting for it to exit...
处理方法：
[root@linuxprobe Desktop]# rm -rf /var/run/yum.pid
据说是因为yum有升级进程，所以要解除锁定需要结束进程。
