Q. Why does my Fedora Core Linux server hangs whey I type or use rpm command? How do I fix the problem as I need to install packages?

A. Under Linux many command creates termporary lock files. If this lock file is not removed by rpm in databases you will see this problem. It is also possible that other apps may try to access same file. Please note that following solution works under:

=> CentOS

=> Fedora Core

=> Redhat Linux/RHEL

There is no clear cut solution exists. You can simply delete those files from /var/lib/rpm/ directory
# /bin/rm /var/lib/rpm/__db.*

The above command removes any locks left on the rpm database and now you should able to use rpm command.