Linux

roadmap.sh: https://roadmap.sh/linux

Suggested path through the Linux nodes. Each node links to its lesson when written.

Nodes

Foundations

• What is Linux?
• Linux vs other operating systems
• Linux distributions (Debian, Ubuntu, Fedora, RHEL, Arch)
• Choosing and installing a distribution
• The Linux kernel
• Open source and the GPL license
• The Filesystem Hierarchy Standard (FHS)

Shell basics

• What is a shell?
• Terminal vs shell vs console
• Common shells (bash, zsh, fish)
• Navigating the filesystem (cd, ls, pwd)
• Working with files and directories (cp, mv, rm, mkdir, touch)
• Reading files (cat, less, more, head, tail)
• Finding files (find, locate, which, whereis)
• Getting help (man, info, —help, tldr)

Text processing

• grep and regular expressions
• sed (stream editor)
• awk
• cut, sort, uniq, wc
• tr and column
• Pipes and redirection
• Standard input, output, and error
• Text editors (vim, nano, emacs)

Users and permissions

• Users and groups
• /etc/passwd, /etc/shadow, /etc/group
• File permissions (rwx, chmod)
• Ownership (chown, chgrp)
• Special permissions (setuid, setgid, sticky bit)
• sudo and the sudoers file
• su and switching users
• Access Control Lists (ACLs)

Processes and jobs

• Viewing processes (ps, top, htop)
• Process states and signals
• Killing processes (kill, killall, pkill)
• Foreground and background jobs (jobs, fg, bg, &)
• nohup and disown
• Process priority (nice, renice)
• systemd and services (systemctl)
• init systems (systemd, SysVinit)

Package management

• apt and dpkg (Debian/Ubuntu)
• yum and dnf (RHEL/Fedora)
• pacman (Arch)
• Snap, Flatpak, and AppImage
• Building from source (make, configure)
• Repositories and PPAs

Filesystem and storage

• Disks and partitions (fdisk, parted, lsblk)
• Filesystems (ext4, xfs, btrfs)
• Mounting and unmounting (mount, umount, /etc/fstab)
• Disk usage (df, du)
• Logical Volume Manager (LVM)
• Swap space
• Symbolic and hard links (ln)
• Archiving and compression (tar, gzip, zip)

Networking

• Network interfaces (ip, ifconfig)
• DNS and /etc/hosts
• Testing connectivity (ping, traceroute, mtr)
• Ports and sockets (ss, netstat)
• Transferring files (scp, rsync, curl, wget)
• SSH and key-based authentication
• Firewalls (iptables, nftables, ufw, firewalld)
• DHCP and static IP configuration

System administration

• Boot process and GRUB
• Runlevels and targets
• Scheduling tasks (cron, at, systemd timers)
• Logging and journald (journalctl, /var/log)
• Environment variables and shell config
• Kernel modules (lsmod, modprobe)
• Performance monitoring (vmstat, iostat, sar)
• Backups and recovery

Security and hardening

• SSH hardening
• SELinux and AppArmor
• User and password policies
• fail2ban
• System updates and patching
• Auditing (auditd)

Scripting and automation

• Shell scripting basics
• Bash variables and conditionals
• Loops and functions
• Automating administrative tasks
• Configuration management overview (Ansible)

Resources

See resources.md.

Project ideas

• Provision a fresh VM and write a bootstrap shell script that creates users, hardens SSH, configures a firewall, and installs your baseline packages.
• Build a system health dashboard that collects CPU, memory, disk, and network stats via /proc and cron, then logs them to a file with rotation.
• Set up an automated, incremental backup of a directory to a remote host using rsync over SSH on a systemd timer.