Warning
Use a sudo-capable account, keep shell history for audit, and back up critical paths before changing boot, SSH, or package state.
What you will achieve
Cheap insurance before apt dist-upgrade or manual config edits.
1) Create timestamped backup folder
sudo mkdir -p /root/backups/prechange-$(date +%F)2) Archive /etc and selected /var data
sudo tar -czf /root/backups/prechange-$(date +%F)/etc.tar.gz /etc
sudo tar -czf /root/backups/prechange-$(date +%F)/var-www.tar.gz /var/www3) Verify archive integrity
sudo tar -tzf /root/backups/prechange-$(date +%F)/etc.tar.gz | head