Linux Roadmap

Goal: Get comfortable with Linux as a system — how it's organized, how you interact with it, and how it manages files and users.

• What is Linux? Kernel vs OS, distributions, why it matters.
• Directory Structure: The FHS — every major directory explained.
• Terminal & Shell: stdin/stdout/stderr, pipes, redirection, PATH.
• File Permissions & Inodes: rwx bits, ownership, hard vs soft links.

Goal: Understand what happens from the moment you press the power button to the moment your desktop appears.

• GRUB Bootloader: How the kernel gets loaded from disk.
• Kernel Startup: initramfs, root pivot, and early boot.
• systemd: Units, targets, service lifecycle, and boot ordering.
• journald: Structured logging and how to read it.

Goal: Learn how Linux creates, runs, and terminates processes — and how the CPU decides what to run next.

• fork() & exec(): How every process is born.
• CFS Scheduler: How Linux keeps things fair.
• Signals: SIGKILL, SIGTERM, SIGHUP and how they work.
• /proc filesystem: A live window into every running process.

Goal: Understand how Linux uses RAM — virtual memory, paging, swap, and what happens when memory runs out.

• Virtual Memory: Why every process thinks it owns all of RAM.
• Paging & Page Tables: The translation from virtual to physical.
• Swap: When RAM runs out, what happens next.
• OOM Killer: How Linux decides which process to sacrifice.

Goal: Learn how Linux manages disks, block devices, and the I/O path from application to hardware.

• Block Devices: How the kernel sees disks and SSDs.
• I/O Scheduler: How Linux queues and reorders disk requests.
• LVM: Flexible disk management without partitions.
• RAID: Redundancy and performance across multiple disks.

Goal: Understand the Linux network stack from socket to wire — and how to control and inspect every layer.

• Networking Stack: How packets flow from app to NIC.
• iptables & nftables: Firewalling and packet filtering.
• Network Namespaces: How Docker isolates networks.
• Routing Table: How Linux decides where to send packets.

Goal: Understand the Linux primitives that make containers possible — namespaces, cgroups, and OverlayFS.

• Namespaces: PID, net, mnt, uts, user — what each isolates.
• cgroups: CPU, memory, and I/O limits per group.
• seccomp: Restricting which syscalls a process can make.
• OverlayFS: How container image layers work on disk.

Goal: Learn the mandatory access control systems, capability model, and audit tools that keep Linux systems secure.

• SELinux: Labels, policies, and enforcement modes.
• AppArmor: Profile-based access control.
• Capabilities: Breaking root into fine-grained permissions.
• auditd: Logging and tracing security events.

Goal: Learn the tools that let you see inside a running Linux system — and fix problems you can't see any other way.

• strace: Trace every system call a process makes.
• perf: Hardware performance counters and flame graphs.
• eBPF: The superpower for safe, dynamic kernel instrumentation.
• ftrace: Kernel function tracing without modifying code.