# commands.txt — useful shell commands
# cm2.cz/f/commands.txt

# ---------- system ----------
uptime                          # how long the system has been running
df -h                           # disk usage, human readable
free -h                         # memory usage
top -bn1 | head -20             # one-shot process snapshot

# ---------- network ----------
ss -tlnp                        # listening TCP ports
curl -I https://example.com     # HTTP headers only
dig +short example.com          # DNS lookup

# ---------- nginx ----------
nginx -t                        # test config
systemctl reload nginx          # reload without downtime
tail -f /var/log/nginx/access.log

# ---------- certbot ----------
certbot renew --dry-run         # test renewal
certbot certificates            # list current certs

# ---------- git ----------
git log --oneline -10
git diff --stat HEAD~1