【遇到的问题】centos7使用yum命令报错。

遇到的问题：

今天在用yum安装的时候报以下错误，接下来记录我处理这个问题的步骤。

Loaded plugins: fastestmirror, langpacks
Existing lock /var/run/yum.pid: another copy is running as pid 74689.
Another app is currently holding the yum lock; waiting for it to exit…
The other application is: PackageKit
Memory : 29 M RSS (1.4 GB VSZ)
Started: Tue Dec 7 10:43:45 2021 - 00:04 ago
State : Sleeping, pid: 74689
Another app is currently holding the yum lock; waiting for it to exit…
The other application is: PackageKit
Memory : 259 M RSS (1.6 GB VSZ)
Started: Tue Dec 7 10:43:45 2021 - 00:06 ago
State : Sleeping, pid: 74689

解决办法：

1、输入命令：rm -f /var/run/yum.pid
2、重新输入yum命令即可。
备注：造成这个报错的原因可能是系统自动升级正在运行，yum在锁定状态中，我选择强行解除锁定。