Study plan
- Phase 1
Shell & filesystem
1 week- Navigation, globbing, and pipelines
- Users, groups, chmod/chown, and ACLs overview
- Finding files, text processing with grep/sed/awk
- Phase 2
Processes & services
1 week- Process tree, signals, and job control
- systemd units, journals, and service debugging
- Cron and timers
- Phase 3
Networking & security
1–2 weeks- IP, DNS, firewall basics (iptables/nftables overview)
- SSH keys, hardening checklists
- Package managers and compiling from source when needed