If you get the next message when running a yum command:
# yum install xxx*
Existing lock /var/run/yum.pid: another copy is running as pid 4112.
Another app is currently holding the yum lock; waiting for it to exit...
The other application is: yum
Memory : 109 M RSS (412 MB VSZ)
Started: Sat Dec 25 15:01:12 2010 - 00:31 ago
State : Sleeping, pid: 4112
It is because there is another yum instance running or dead. The origin of this situation is that the system does not support YUM concurrent operations. A circumstance that usually occur is when yum-updatesd is running. You may solve it with:
$ su -
password
# service yum-updatesd stop
<my yum commands>
# service yum-updatesd start
This only works if yum-updatesd is locking the system. If it is another yum application, then simply wait, and only as a last resort, if you think that the application is dead and unresponsive:
su -
password
kill -kill <pid>
Where <pid> is the process id of the application.
