The CompTIA Linux+ animated track.

Boot process, Filesystem Hierarchy Standard (FHS), server architectures (x86_64, AArch64, RISC-V), package families (RPM vs dpkg), GUI components (Wayland, X), and open source / proprietary licensing.

Kernel modules (depmod, lsmod, modprobe), device discovery (dmesg, dmidecode, lspci, lsusb, lshw), and initrd tools (dracut, mkinitrd).

LVM (pv*/vg*/lv* commands), partitions (parted, fdisk, growpart), filesystems (xfs, ext4, btrfs, tmpfs), mounting (/etc/fstab, autofs), RAID with mdadm, and network mounts (NFS, SMB).

/etc/hosts, /etc/resolv.conf, NetworkManager (nmcli), Netplan, and the common network tools — ip, ss, dig, mtr, traceroute, tcpdump, nmap, curl.

Environment variables (PATH, HOME, SHELL), channel redirection (<, >, >>, |, here docs), shell utilities (awk, grep, sed, sort, uniq, xargs, tee), text editors (vi/vim, nano).

cd, cp, mv, rm, mkdir, find, locate, ln (symbolic vs hard links), stat, lsof, sdiff. Plus device types in /dev (block, character, special).

ps, top, htop, atop, pstree, /proc/<PID>, kill/killall (signals: HUP, TERM, KILL), nice/renice, job control (bg/fg/jobs/nohup), scheduling (cron, at, anacron).

Package managers (dnf, apt, rpm, dpkg), language-specific (pip, cargo, npm), repository management, sandboxed apps, GPG signatures. Basic configs for DNS, DHCP, HTTP (httpd/Nginx), SMTP, IMAP4, NTP/PTP.

Unit types (services, timers, mounts, targets), systemctl + state management (start/stop/enable/disable/mask), and utilities (systemd-analyze, hostnamectl, timedatectl, resolvectl, sysctl).

Runtimes (Podman, Docker, containerd, runC), image operations (Dockerfile FROM/CMD/ENTRYPOINT/USER, layers, tags), container operations (run/exec/logs/inspect), volumes (incl. SELinux context, overlay), networks (bridge, host, macvlan, ipvlan, overlay), privileged vs unprivileged.

firewalld (zones, services, rich rules, runtime vs permanent), ufw, nftables, iptables, ipset. Netfilter modules. Address translation (NAT, PAT, DNAT, SNAT), stateful vs stateless, IP forwarding.

Privilege escalation (sudo, /etc/sudoers, NOEXEC/NOPASSWD, visudo, wheel/sudo group, su -). File attributes (chattr/lsattr — immutable, append-only). Permissions (chmod octal/symbolic, chown, special bits, umask). ACLs (setfacl/getfacl). SELinux (restorecon, semanage, chcon, getsebool/setsebool, audit2allow, sealert, enforcing/permissive/disabled). Secure SSH (key vs password, PermitRootLogin, AllowUsers/Groups, SSH tunneling, SFTP). fail2ban, chroot, secure boot (UEFI). Avoid Telnet/FTP/TFTP.

Data at rest (GPG file encryption, LUKS2 filesystem encryption, Argon2). Data in transit (OpenSSL/LibreSSL, TLS versions, WireGuard). Hashing (SHA-256, HMAC), weak algorithm removal. Certificate management — trusted root certs, no-cost vs commercial CAs, avoiding self-signed.

Detection (anti-malware, IoCs), vulnerability scanning (CVE, CVSS, backporting patches, port scanners, protocol analyzers), standards (OpenSCAP, CIS Benchmarks), file integrity (AIDE, rkhunter, signed packages), secure data destruction (shred, badblocks, dd from /dev/urandom, cryptographic destruction), security banners (/etc/issue, /etc/issue.net, /etc/motd).

IaC (Ansible playbooks/inventory/modules/facts, Puppet classes/certificates, OpenTofu provider/resource/state/API), unattended deployment (Kickstart, cloud-init), CI/CD (version control, shift-left testing, GitOps, pipelines, DevSecOps), and deployment orchestration (Kubernetes Pods/Deployments/Services/Volumes/ConfigMaps/Secrets, Docker Swarm, Docker/Podman Compose).

Parameter expansion ${var}, command substitution $(cmd), subshells, functions, IFS/OFS, conditionals (if/case), loops (for/while/until), the #! interpreter directive, comparisons (numeric -eq/-gt/..., string =/==/=~, file -d/-f/-z), regex with =~, variables (env/args, export/local/set/unset), and return codes ($?).

.gitignore, init/clone/config, add/commit/diff/log, branch/checkout, fetch/pull/push, merge/squash/rebase, reset/stash, and tagging.

Kernel panic, data/kernel corruption, package dependency issues, FS will-not-mount, server-not-turning-on, OS-filesystem-full, inode exhaustion, partition-not-writable, segfaults, GRUB misconfiguration, killed processes, PATH issues, systemd unit failures, missing drivers, quota issues, memory leaks.

Firewall misconfig, DHCP/DNS issues, interface misconfig (MTU mismatch, bonding, MAC spoofing, wrong subnet), routing/gateway, IP conflicts, dual-stack (IPv4/IPv6), link down, link negotiation.

SELinux issues (policy, context, booleans), file/directory permission issues (ACLs, attributes), account access, unpatched vulnerabilities, exposed/misconfigured services, remote access issues, certificate issues, misconfigured package repos, obsolete protocols/ciphers, cipher negotiation issues.

Swapping, OOM, slow app response, system unresponsiveness, high CPU/load average, high context switching, slow startup, high I/O wait, packet drops/jitter, random disconnects/timeouts, high latency, high disk latency, low throughput, blocked processes, hardware errors, CPU bottlenecks.