Working with RPMs on CentOS

I'm pretty much going to just start spitting all my favorite rpm commands here. Assuming CentOS, but most of this is applicable to any rpm based distro.

List every rpm installed on your system, pipe it through grep to find something specific
rpm -qa

Info about a specific rpm, version number, build host an other useful info
[root@webapp01 ~]# rpm -qi php
Name : php Relocations: (not relocatable)
Version : 5.2.2 Vendor: (none)
Release : 3 Build Date: Thu 13 Mar 2008 04:31:00 PM PDT
Install Date: Fri 14 Mar 2008 11:02:12 AM PDT Build Host: dev.myhost.com
Group : Development/Languages Source RPM: php-5.2.2-3.src.rpm
Size : 12049373 License: The PHP License v3.01
Signature : (none)
URL : http://www.php.net/
Summary : The PHP HTML-embedded scripting language. (PHP: Hypertext Preprocessor)
Description :
PHP is an HTML-embedded scripting language. PHP attempts to make it
easy for developers to write dynamically generated webpages. PHP also
offers built-in database integration for several commercial and
non-commercial database management systems, so writing a
database-enabled webpage with PHP is fairly simple. The most common
use of PHP coding is probably as a replacement for CGI scripts.

The php package contains the module which adds support for the PHP

What rpm a specific file is from
rpm -qf /path/filename

List everything installed by an rpm
rpm -ql packagename

Turn any perl CPAN module into an rpm and install it
cpan2rpm -i Getopts::Long

After you've installed a src rpm, change into /usr/src/redhat/SPECS/ and execute this using your package's specfile and it builds an rpm and installs it. If you don't have a src rpm, but you've got a specfile for a source tarball, put the specfile in /usr/src/redhat/SPECS/ and the tarball in /usr/src/redhat/SOURCES .
rpmbuild -bi packname.spec

Creates an rpm repo in your current directory from the rpms in that directory
createrepo .

Searches all your rpm repos for a specific file
yum provides '*/rpmbuild'

List/Install/Remove package groups. Package groups are groups of rpms that are generally needed together, IE 'Development Libraries' or 'KDE (K Desktop Environment)'
yum grouplist / yum groupinstall / yum groupremove