One message I encountered the other day when I was installing some RPM’s was “Warning: RPMDB altered outside of yum.”. Here’s what it means and how you can avoid it.

Have You Used The Command RPM Recently?

When I installed MySQL this is the partial response log.

Running transaction test
Transaction test succeeded
Running transaction
Warning: RPMDB altered outside of yum.
Installing: mysql-community-common-5.6.22-2.el7.x86_64
Erasing: 1:mariadb-libs-5.5.35-3.el7.x86_64

Now you may wonder why it says “RPMDB altered outside of yum”. In this case, I used the command RPM to install a package from an outside source namely

rpm -ivh http://somepackage.rpm

However, the yum package manager does not like it when you install outside packages via RPM and issues this warning.

In general, it is best to avoid the command RPM and install packages only via yum. However, that is not always practical.

Installing EPEL on CentOS

In order to avoid problems like that it is best to use official packages like EPEL. EPEL stands for Extra Packages for Enterprise Linux and is basically a package that includes all sorts of useful tools. It is available for CentOS 5,6 and 7

Follow this guide to learn how to properly install EPEL

In order to install EPEL you will retrieve a GPG key in order to avoid hijacking of your machine by 3rd-parties.