General / Basic:

• dpkg-reconfigure tzdata --> set timezone
• htop
• nettop
• nethogs
• tasksel --> package installation (LAMP)
• less xxxx.log --> / to search and G goes to the end
• journalctl -f or dmesg --> syslog follow

Packages:

• apt list --upgradable
• apt upgrade --show-upgraded

Networking:

• lsof -iTCP -sTCP:LISTEN
• lsof -iTCP -sTCP:ESTABLISHED
• lsof -UDP
• ufw status
• hostname --> host
• hostname -f --> fqdn
• hostname -F XXX.XXX --> set fqdn

Disk:

• df -h --> disk usage all partitions
• du -hc | sort -rh | head -20 --> show file/folder sizes with total, add sort, then show only top 20

Files:

• /etc/hostname
• /etc/hosts