Roadmap¶

A progress tracker for the whole Linux folder. Tick topics in your own copy as you learn them; the Track and Weight after each entry show what to prioritise before an interview.

00 Foundations¶

• What Is Linux (Core, Low)
• Kernel vs OS vs Distro (Core, Med)
• Distributions (Core, Low)
• Linux vs Windows (Core, Low)
• Architecture (Core, High)
• System Information (Core, Med)

01 Shell and CLI¶

• Shell Basics (Core, Med)
• Getting Help (Core, Low)
• Command Resolution (Core, Med)
• Variables and Environment (Core, High)
• Locale and Encoding (Core, Low)
• Quoting and Expansion (Core, Med)
• Streams and Redirection (Core, High)
• Exit Codes and Chaining (Core, High)
• Text Editors (Core, Low)
• Scripting Essentials (RHCSA, Med)

02 Files and Filesystem¶

• Filesystem Hierarchy (Core, High)
• File Types (Core, Med)
• Navigation and Listing (Core, Low)
• File Operations (Core, Med)
• Inodes and Links (Core, High)
• File Descriptors (Advanced, High, internals)
• Finding Files (Core, High)
• Archiving and Compression (Core, Med)

03 Text Processing¶

• Viewing and Comparing (Core, Med)
• grep and Regex (Core, High)
• sed (Core, High)
• awk (Core, High)
• Cut, Sort, Uniq and Tr (Core, High)
• xargs and tee (Core, Med)
• JSON and YAML on the CLI (Core, Med)

04 Users and Access¶

• Users (Core, High)
• Groups (Core, High)
• Passwords and Aging (Core, Med)
• Sudo and Su (Core, High, internals)
• PAM (Core, Low)
• Login Sessions (Core, Low)
• Centralized Identity (Advanced, Low)

05 Permissions¶

• Basic Permissions (Core, High)
• umask (Core, Med)
• Special Permissions (Core, High)
• ACL (RHCSA, Med)
• File Attributes (Core, Med)

06 Package Management¶

• Packaging Concepts (Core, Med)
• rpm and dnf (Core, Med)
• dpkg and apt (Core, Med)
• Repositories (Core, Low)
• Flatpak and Snap (RHCSA, Low)
• Shared Libraries (Advanced, Med, internals)
• Other Install Methods (Core, Low)

07 Processes¶

• Process Fundamentals (Core, High)
• Process Lifecycle (Advanced, High, internals)
• Viewing Processes (Core, High)
• Process States (Core, High)
• Signals (Core, High, internals)
• Job Control (Core, Med)
• Priority and Nice (Core, Med)
• System Calls and Tracing (Advanced, High, internals)

08 Systemd and Services¶

• Init and Targets (Core, Med)
• systemctl (Core, High)
• Unit Files (Core, High)
• Writing a Service (Core, Med)
• Systemd Toolbox (Core, Low)

09 Logging¶

• Log Locations (Core, High)
• journalctl (Core, High)
• rsyslog (Core, Low)
• logrotate (Core, Med)
• Log Parsing Recipes (Core, High)

10 Scheduling¶

• cron and at (Core, High)
• Systemd Timers (Core, Med)

11 Kernel and Hardware¶

• proc and sys (Core, High)
• sysctl (Core, High)
• Kernel Modules (Core, Med)
• Devices and udev (Advanced, Low)
• dmesg and Kernel Messages (Core, Med)

12 Storage¶

• Disks and Devices (Core, Med)
• Partitioning (RHCSA, Med)
• Filesystems (Core, Med)
• Mounting and fstab (Core, High)
• Swap (Core, Med)
• LVM (Core, High)
• Resizing and Cloud Disks (Core, Med)
• Disk Usage (Core, High)
• Quotas (RHCSA, Low)
• Backup and Restore (Core, Med)
• RAID and Encryption (Advanced, Low)

13 Networking¶

• Interfaces and Addresses (Core, High)
• Network Configuration (Core, Med)
• Routing (Core, High)
• DNS Resolution (Core, High)
• Ports and Sockets (Core, High)
• Sockets and TCP States (Advanced, Med, internals)
• Connectivity Testing (Core, High)
• Packet Capture (Core, Med)
• Bridges, Bonds and VLANs (Advanced, Low)
• Time and Timezones (Core, Med)
• Reverse Proxy and Load Balancing (Core, Med)
• VPN (WireGuard) (Advanced, Low)
• Troubleshooting Ladder (Core, High)

14 SSH and Remote Access¶

• SSH Client (Core, High)
• SSH Tunnels (Core, Med)
• sshd Server (Core, Med)
• File Transfer (Core, Med)
• SSH Troubleshooting (Core, High)

15 Security¶

• firewalld and ufw (Core, Med)
• nftables and iptables (Core, Med)
• SELinux (RHCSA, Med, internals)
• AppArmor (Core, Low)
• Capabilities (Advanced, Med)
• auditd (Advanced, Low)
• GPG (Core, Low)
• OpenSSL and Trust Store (Core, Med)
• Compliance and Integrity (Advanced, Low)
• Hardening Checklist (Core, Med)

16 Boot and Recovery¶

• Boot Process (Core, High)
• GRUB2 (RHCSA, Med)
• Recovery (RHCSA, Med)
• Kernel Panic (Advanced, Med, internals)
• Kernel Updates (Core, Low)

17 Performance and Troubleshooting¶

• Methodology (Core, High)
• CPU and Load (Core, High)
• Memory (Core, High)
• Virtual Memory (Advanced, High, internals)
• Disk I/O (Core, Med)
• Limits and File Descriptors (Core, High)
• Profiling and Tracing (Advanced, Med, internals)
• Monitoring and Capacity (Core, Low)
• Tuning (RHCSA, Low)

18 Network Storage¶

• NFS (Core, Med)
• autofs (RHCSA, Low)
• Samba and CIFS (RHCSA, Low)
• iSCSI and NBD (Advanced, Low)

19 Containers¶

• Namespaces (Core, High, internals)
• cgroups (Core, High, internals)
• overlayfs and chroot (Core, Med)
• Containers vs VMs (Core, High)
• Podman and Quadlet (RHCSA, Med)

20 Virtualization and Provisioning¶

• KVM and libvirt (Advanced, Low)
• VM Images and Cloning (Advanced, Low)
• cloud-init and Kickstart (Core, Low)

Labs¶

• Users and Permissions Lab
• Processes and Services Lab
• Storage and LVM Lab
• Networking Lab
• Security Lab
• Containers by Hand Lab
• RHCSA-Style Tasks
• Break-Fix Lab

Scenarios¶

• Cannot Log In or Use Sudo
• Binary Won't Execute
• Process Won't Die
• Service Won't Start
• Cron Job Not Running
• Disk Full
• DNS Not Resolving
• Cannot SSH
• Service Unreachable
• Cannot Reach Host
• TLS Certificate Errors
• Permission Denied
• Suspected Compromise
• Server Slow
• Too Many Open Files
• Cannot Fork
• Boot Failure
• High Load, Low CPU
• High Memory and OOM