Check if a package is installed:

$ rpm -qa | grep core
openoffice.org-core-2.3.0-6.10.el5
coreutils-5.97-19.el5
policycoreutils-1.33.12-14.2.el5

List files in a certain package:

$ rpm -ql coreutils

List files in an RPM:

$ rpm -qlp apcupsd-3.14.7-1.x86_64.rpm

Manually install an rpm (as in, not using a repository with a package manager like yum):

$ sudo rpm -i VirtualBox-3.0.6_52128_rhel5-1.x86_64.rpm

Manually remove an rpm:

$ sudo rpm -e VirtualBox

upgrade a package

rpm -Uvh <package>

• rpm -qa | less :list all installed software packages
• rpm -q httpd :show the version of the httpd package, if it is installed
• rpm -qa | grep httpd : show all installed packages that have httpd in their name
• rpm -ql httpd : list all files in the httpd package
• rpm -qd httpd : list all documentation files in the httpd package
• rpm -qc httpd : list all configuration files in the httpd package
• rpm -qi httpd : display information about the package
• rpm -V httpd : verify that the httpd package is correctly installed
• rpm -qf /etc/passwd :determine which package the /etc/passwd file belongs to

To unistall a package:

rpm -e <package name>

rpm -qa | grep -i <packagename>

An RPM is a pre-compiled package containing binaries and config files, etc which can be installed using rpm or yum command line tools. An SRPM or "source RPM" contains everything you need to rebuild a package. Sometimes a binary RPM is not available, you can build a custom RPM using the SRPM file.

• Setting up the RPM build environment
• Rebuilding Source RPMs

Install rpmbuild (from the rpm-build package):

$ sudo yum install rpm-build

Setup your home directory's environment:

$ cp -a /usr/src/redhat/ ~/rpmbuild
$ echo '%_topdir %(echo $HOME)/rpmbuild' > ~/.rpmmacros

Download an SRPM and build:

$ wget http://mirrors.geekymedia.com/centos/python26-2.6-geekymedia1.src.rpm
$rpmbuild --rebuild EMBOSS-5.0.0-1.src.rpm

Install with:

$ sudo rpm -i ~/rpmbuild/RPMS/x86_64/python26-2.6-geekymedia1.x86_64.rpm

If upgrading, use

$ sudo rpm -U ~/rpmbuild/RPMS/x86_64/python26-2.6-geekymedia1.x86_64.rpm

If you have problems with GPG errors, add a line like this to your ~/.rpmmacros:

%_gpg_name Alan

[dag]
name=Dag RPM Repository for Red Hat Enterprise Linux
baseurl=http://dag.linux.iastate.edu/dag/redhat/el5/en/$basearch/dag
gpgcheck=1
enabled=1

 rpm --import http://dag.wieers.com/packages/RPM-GPG-KEY.dag.txt

Check more on this here http://wiki.centos.org/AdditionalResources/Repositories/RPMForge

cd /etc/yum.repos.d
wget http://rpm.pidgin.im/centos/pidgin.repo
yum install pidgin