Ubuntu update

• Show security updates only:

apt-get -s dist-upgrade |grep "^Inst" |grep -i securi 

or

unattended-upgrade --dry-run -d

or

/usr/lib/update-notifier/apt-check -p

• Show all upgradeable packages

apt-get -s dist-upgrade | grep "^Inst"

• Install security updates only

apt-get -s dist-upgrade | grep "^Inst" | grep -i securi | awk -F " " {'print $2'} | xargs apt-get install

via Ask Ubuntu (http://askubuntu.com/a/217999/154649)