To edit files as a superuser you may also consider using "nano" text editor that works within bash as "vi" but much more simple:

Code:
sudo cp /etc/samba/smb.conf /etc/samba/smb.conf.backup

sudo nano /etc/samba/smb.conf
Need V4 Kernel -- is UBUNTU 16 Solid and stable as CENTOS 7.2-nano.png