The Yellowdog Updater, Modified has more features than most of us will ever need. Below are some hopefully useful examples that will help keep your system maybe secure by replacing old known bugs with new unknown, thus ensuring that only the NSA and people who hacked it have access to your kernel’s internals.

Security Updates

How does one go about installing the critical security updates. If you are feeling bold (and have good backups), you can just do “yum update”. However, if you are a professional sysamdin and are flying by the seat of your pants, I’d suggest using the awesome but little-known Yum security plugin:

# Install the plugin
yum -y install yum-plugin-security

# View available critical security upgrades
yum --security check-update

# View available Bugzilla updates for installed packages
yum updateinfo list bugzillas

# View a summary of advisories
yum updateinfo summary

# Update packages with security erratas to the latest security errata package
yum --security update-minimal

# Update packages with security erratas to the latest package version
yum --security update

General Yum Commands

# List all available packages from defined repos
yum list

# List installed packages
yum list installed

# See which package provides a particular file or directory
yum provides <pathname>

# List/install/upgrade/uninstall software groups
yum grouplist
yum groupinstall '<group_name>'
yum groupupdate '<group_name>'
yum groupremove '<group_name>'

Repo Operations

# List enabled repos
yum repolist

# List all defined repos
yum repolist all

Yum Verify

# Install Yum Utils and Verify plugins
yum -y install yum-utils.noarch yum-verify

# Verify packages containing pathname
# Example below will show all packages with paths matching '*bin/*' pattern
yum verify --verify-filenames='*bin/*'

# Verify packages and re-install those with missing files
# This can be useful for recovering damaged packages
yum verify --verify-filenames='*bin/*' | grep "^[a-z].*:.*" | awk '{print $1}' | while read line ; doyum -y reinstall “${line}” ; done

You can find more information about verify and re-install operations here.