apt, dist-upgrade noninteractive default values
# ubuntu noninteractive with default values
# http://superuser.com/questions/164553/automatically-answer-yes-when-using-apt-get-install
DEBIAN_FRONTEND=noninteractive dpkg --configure -a --force-confdef --force-confold
apt-get update
sudo DEBIAN_FRONTEND=noninteractive apt-get upgrade -y --force-yes -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold"
apt-get -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" dist-upgrade
# to install maintaner version use:
-o Dpkg::Options::="--force-confnew"
# on trusty
-force-yes
# on xenial use with
--allow-downgrades --allow