Yum

YUM, it's not just good eatin', it's also for updating your RedHat (or CentOS) packages. https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/ch-yum.html

What are the top 20 yummiest commands? http://www.tecmint.com/20-linux-yum-yellowdog-updater-modified-commands-for-package-mangement/

Sometimes, you want to use a new repository. Like when installing Jenkins (although it's found in the regular repos, so maybe this isn't the best example for needing a separate repo)

from http://pkg.jenkins-ci.org/redhat/

sudo wget -O /etc/yum.repos.d/jenkins.repo http://pkg.jenkins-ci.org/redhat/jenkins.repo
sudo rpm --import http://pkg.jenkins-ci.org/redhat/jenkins-ci.org.key
sudo yum install jenkins

How do I find what repository provides a given package?: You use repoquery

For example, you have a package called glibc-devel-2.12-1.107.el6_4.4.i686

repoquery -i glibc-devel-2.12-1.107.el6_4.4.i686

Name        : glibc-devel
Version     : 2.12
Release     : 1.107.el6_4.4
Architecture: i686
Size        : 976153
Packager    : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
Group       : Development/Libraries
URL         : http://sources.redhat.com/glibc/
Repository  : rhel-6-workstation-rpms
Summary     : Object files for development using standard C libraries.
Source      : glibc-2.12-1.107.el6_4.4.src.rpm
Description :
The glibc-devel package contains the object files necessary
for developing programs which use the standard C libraries (which are
used by nearly all programs).  If you are developing programs which
will use the standard C libraries, your system needs to have these
standard object files available in order to create the
executables.

Install glibc-devel if you are going to develop programs which will
use the standard C libraries.

List the files of a package with repoquery

sudo repoquery -q -l mysql-connector-java

If you don't have the repoquery command, install yum-utils first.