CLI Essentials

Navigation and files

• pwd — show working directory
• ls -lha — list with permissions and sizes
• cd - — toggle between last two directories
• find . -maxdepth 2 -type f -name '*.log' — locate logs quickly
• du -sh ./* | sort -h — see directory sizes

Editing safely

• sudo cp file{,.bak} — make a quick backup
• sudo tee /etc/app/config.yaml <<'EOF' ... EOF — safe overwrite
• sudoedit /etc/app/config.yaml — respect sudoers editor

Processes and resources

• ps -eo pid,ppid,%cpu,%mem,cmd --sort=-%cpu | head — hot processes
• top/htop — live view
• free -h — memory snapshot
• uptime — load averages
• journalctl -f -u app.service — follow service logs

Networking

• ip a / ip r — addresses and routes
• ss -tulpn | head — listening sockets
• curl -v http://127.0.0.1:8080/health — local health check
• traceroute / mtr — path checks
• tcpdump -i eth0 port 443 -c 20 — capture samples (requires sudo)

Compression and archives

• tar -czf backup.tar.gz /srv/app — create archive
• tar -xzf backup.tar.gz -C /restore — extract
• zip -r files.zip dir/ — zip directory

Quality-of-life aliases (examples)

alias ll='ls -lha --group-directories-first'
alias cls='clear && printf "\\033c"'
alias ktop='kubectl top pod'