LWM-Linux/08 - Advanced Linux Administration/Advanced Package Management (YUM).md

Advanced Package Management (YUM)

1. Understanding YUM:

YUM is a package manager used in Red Hat-based Linux distributions like CentOS, Fedora, and RHEL. It simplifies the process of installing, updating, and removing software packages.

2. Basic YUM commands:

• Install a package: yum install package_name
• Remove a package: yum remove package_name
• Update all packages: yum update
• Search for a package: yum search keyword
• Get information about a package: yum info package_name

3. Working with repositories:

• List configured repositories: yum repolist
• Add a repository: Create a .repo file in /etc/yum.repos.d/ with the following structure:

  [repo-name]
  name=Repository Name
  baseurl=http://repo.url
  enabled=1
  gpgcheck=1
  gpgkey=http://repo.url/RPM-GPG-KEY
  

• Enable/disable a repository: yum-config-manager --enable/--disable repo-name

4. Advanced package operations:

• Install a specific version: yum install package_name-version
• Downgrade a package: yum downgrade package_name
• Reinstall a package: yum reinstall package_name
• List dependencies: yum deplist package_name
• Install only dependencies: yum depinstall package_name

5. Group operations:

• List available groups: yum grouplist
• Install a group: yum groupinstall "Group Name"
• Remove a group: yum groupremove "Group Name"
• Update a group: yum groupupdate "Group Name"

6. History and rollback:

• View transaction history: yum history
• Undo a transaction: yum history undo transaction_id
• Redo a transaction: yum history redo transaction_id

7. Cleanup operations:

• Clean all caches: yum clean all
• Remove orphaned packages: yum autoremove

8. Using YUM plugins:

• List installed plugins: yum list installed | grep yum-plugin
• Install a plugin: yum install yum-plugin-name
• Enable/disable a plugin: Edit /etc/yum/pluginconf.d/plugin-name.conf

9. Creating and using local repositories:

• Install createrepo: yum install createrepo
• Create a repository: createrepo /path/to/repo
• Add the local repo to YUM: Create a .repo file in /etc/yum.repos.d/

10. YUM variables and configuration:

- View YUM variables: `yum variables`
- Set variables: Edit /etc/yum/vars/ or use `--setopt` in commands
- Configure YUM behavior: Edit /etc/yum.conf

11. Using alternative package managers:

- DNF (Dandified YUM): A next-generation replacement for YUM
- Use `dnf` instead of `yum` in commands for newer distributions

12. Security considerations:

- Always use gpgcheck=1 in repository configurations
- Regularly update the system with `yum update`
- Use `yum update --security` for security updates only

13. Troubleshooting:

- Check YUM logs: /var/log/yum.log
- Debug YUM operations: Add `-v` or `--verbose` to commands
- Resolve dependency issues: Use `yum depsolve` or `yum check`