How To Configure Secure Updates and Installations in WordPress on Ubuntu | DigitalOcean https://www.digitalocean.com/community/tutorials/how-to-configure-secure-updates-and-installations-in-wordpress-on-ubuntu
apt – How to install updates via command line? – Ask Ubuntu https://askubuntu.com/questions/196768/how-to-install-updates-via-command-line
package management – How can I install just security updates from the command line? – Ask Ubuntu http://askubuntu.com/questions/194/how-can-i-install-just-security-updates-from-the-command-line
AutomaticSecurityUpdates – Community Help Wiki https://help.ubuntu.com/community/AutomaticSecurityUpdates