---Yum and RPM Commands---
rpm --queryformat="%{NAME}\n" -qa | less ##show all packages installed by name | through less unless you read REALLY fast
rpm --queryformat="%{NAME}-%{VERSION}-%{RELEASE}.%{ARCH}: %{INSTALLTIME:date}\n" -qa ##same as above, but with more details
rpm --queryformat="%{NAME}-%{VERSION}-%{RELEASE}.%{ARCH}: %{INSTALLTIME:date}\n" -qa | sort -k 3 -k 5 | sed 's/-[0-9].*//' ##same as above but sort by date install and remove everything after package name
package-cleanup --leaves ##remove unused packages, clean your junk up!
yum update ##check for package updates and interactively ask user if they want to upgrade
yum update --exclude=kernel* ##check for package updates, excluding the kernel, and interactively ask the user if they want to upgrade
yum list installed brasero ##show if package 'brasero' is installed
yum install brasero ##install package 'brasero' and it's depenencies
yum install yum-utils ##install 'yum-utils', this yum extension includes yumdownloader which allows you to download packages without installing them
yumdownloader --resolve --destdir=/home/
yum history info brasero ##show yum history for package 'brasero', also shows dependencies that were installed
yum history info brasero | grep -o '[^ ].x86_64[^ ]\|[^ ]noarch[^ ]' ##See Grep and Find commands, useful to download only the packages and dependencies that were needed at the time of installation of package 'brasero'
yum history list all ##show all yum packages installed by history ID
yum history info 11 ##show history ID '11' details, shows packages that were installed/updated, etc
yum whatprovides iostat ##show which package 'iostat' is a part of, in this case, 'iostat' is a part of 'sysstat'
package-cleanup --dupes ##check for duplicate packages that on the system
package-cleanup --cleandupes ##clean installed duplicate packages
############################################ ###---Install and Use Local Repository---### ############################################
yum install yum-utils createrepo ##these packages are needed to create your own repository
mkdir /mnt/localrepo ##create directory where local packages will be stored
touch /etc/yum.repos.d/local.repo ##create a local repo file, this file is used for yum to know where your local repository is located, add the following text to 'local.repo', make sure there aren't any extra spaces
[lclrepo] name=Local Repo baseurl=file:///mnt/localrepo enabled=1 gpgcheck=0
rpm --import /etc/pki/rpm-gpg/RPM* ##optional, if you want to use GPG to check signed rpms, and change the local.repo line gpgcheck=0 to 1
#########################################
###---Test and Use Local Repository---###
#########################################
repotrack -a x86_64 iotop -p /mnt/localrepo/ ##download 'iotop' to local repository for testing, 'iotop' shows disk I/O by process, '-a x86_64' means download only the '-a x86_64' packages, doesn't always work, sometimes downloads i686
yum clean all ##clean the yum cache
cd /etc/yum.repos.d
rename .repo .repo.bak * ##change to yum.repo.d directory and rename all of the repo files to repo.bak, to remove them from the possible repos for yum to pull repos from
mv local.repo.bak local.repo ##rename local.repo.bak to local.repo so that it's the only repo available to yum
createrepo /mnt/localrepo/ ##tell yum where the repository is located
yum update ##update the repo cache from the only available repo, local.repo
yum install iotop ##install iotop, did it work? You should see yum using lclrepo and lclrepo/primary_db for the 'iotop' installation
###########################################################
###---Restore Yum Back to Using Internet Repositories---###
###########################################################
cd /etc/yum.repos.d
rename .repo.bak .repo *
yum clean all
yum update ##This will update the yum cache and update ALL packages, if you just want to update the yum cache answer 'n' after the yum update completes
######################################################################### ###---Install EPEL for Centos (Extra Packages for Enterprise Linux)---### #########################################################################
###---Version 6.x/7.x---###
yum install epel-release ####download the EPEL package list
###---Manual Version 6.x install---###
rpm -Uvh http://mirrors.kernel.org/fedora-epel/6/i386/epel-release-6-8.noarch.rpm ##download the EPEL package list
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6 ##import the GPG key to verify rpm signature integrity
yum repolist ##show repolist, look for the 'repo id' line containg 'EPEL', this will show that the EPEL repolsitory list has been added to your Centos box