centos 7Another app is currently holding the yum lock; waiting for it to exit...

The message "Another app is currently holding the yum lock; waiting for it to exit..." typically occurs when another instance of yum or another package manager is already running on your CentOS 7 system.

To resolve this issue, you can follow these steps:

1. Check for any running instances of yum:

   ps aux | grep yum

2. If you find any running processes related to yum, you can either wait for them to complete or kill them using the `kill` command.

3. Try to clean the yum cache by running the following command:

   sudo yum clean all

4. After cleaning the cache, you can try running your desired yum command again.

If the issue persists, you may need to reboot your system to make sure there are no lingering processes holding the yum lock.

Note: It's important to exercise caution when terminating processes, as killing essential system processes can lead to system instability.