Linux system administration on RHEL 9

Build practical Linux administration skills on RHEL 9: shell and files, identity and access, services and logs, networking, software, storage, security and rootless containers. Explain each change, verify its useful result, and rehearse recovery on a resettable practice lab. Prepares you for the RHCSA (EX200) exam.

Prepares you for Red Hat Certified System Administrator (RHCSA) (EX200).

Chapters

  1. Build Your Practice Lab: Build a sealed practice lab at home, with Rocky Linux 9 VMs on LXD, so every exercise in this path has a safe place to run and a fast way to reset.
  2. Command-line essentials: Log in to a Linux system, run commands from the Bash shell, and save time with completion, history and line editing.
  3. Files and directories: Find your way around the Linux directory tree, and create, copy, move, link and remove files from the shell, using patterns to work on many files at once.
  4. Getting help: Find answers on the system itself, with manual pages, keyword searches, command help and package documentation, instead of guessing.
  5. Text, editors and the shell environment: Send command output where you want it, search text with grep, edit files with vim, and set up your shell with variables, aliases and startup files.
  6. Users and groups: Create and manage local user accounts and groups, give administrators controlled root access with sudo, and set password policies.
  7. Permissions and ACLs: Read and change file permissions and ownership, build shared team directories with setgid and sticky bits, and grant exceptions with access control lists.
  8. Processes: See what is running, control jobs and signals, and judge and tune how processes share the machine.
  9. Services and the boot process: Manage services with systemd, write your own units, understand the boot sequence and targets, and recover a system that will not boot normally.
  10. Secure remote access: Log in to other machines safely with SSH, authenticate with keys, move files between hosts, and harden the SSH server without locking yourself out.
  11. Logs and time: Read and filter the system logs, keep them across reboots and under control, keep the clock right, and use a calm method to diagnose problems.
  12. Networking: Read and configure a host's network with ip and NetworkManager, manage names and DNS, and troubleshoot connections layer by layer.
  13. Software management: Query and verify installed packages with rpm, manage software with dnf, work with repositories and signatures, build a local repository, and choose module streams and updates.
  14. Archives and file transfer: Bundle and compress data with tar, prove it with checksums, make backups that restore with their metadata, and move data between hosts safely.
  15. Scripts and scheduling: Write shell scripts with arguments, tests and loops, and schedule them with cron, systemd timers and at.
  16. SELinux: Understand SELinux contexts and modes, fix file labels, booleans and ports the right way, and troubleshoot denials without disabling the protection.
  17. Storage and file systems: Partition disks, create and mount XFS, ext4 and swap, make them permanent with fstab, and find and fix space and busy-mount problems.
  18. Logical volume management: Build storage with LVM, grow and shrink volumes online, replace disks without downtime, and diagnose common LVM problems.
  19. Network file systems and autofs: Share a directory from one server, mount it on another with the right access, make the mount permanent or on-demand with autofs, and diagnose the usual failures.
  20. The firewall: Control which network traffic reaches a machine with firewalld, change rules so they survive a reload and a reboot, limit services to chosen hosts, and find out why a connection fails.
  21. Containers with Podman: Run containers as an ordinary user, publish ports and keep data safely, build your own image, and run a container as a systemd service that survives a reboot.
  22. Review and practice: Deliver a small service the way you would in real work, with proof for every requirement, find and repair faults with one method, and leave a tested recovery and a handover note.