The package “unattended-upgrades” comes pretty handy for automatic security updates. Nevertheless there are a couple of settings you have to be aware of.
First you have to install the package “unattended-upgrades” of course. It installs a binary called “unattended-upgrades” which is run daily by the apt cron job:
/etc/cron.daily/apt
After that you have to not only enable unattended-upgrades but also the periodic update of your packages . Create the following file:
/etc/apt/apt.conf.d/02periodic
APT::Periodic::Unattended-Upgrade "1";
APT::Periodic::Update-Package-Lists "1";
“1” means updating and running unattended-upgrades every day.
There are a couple of more options. Take a look at the following files:
/etc/cron.daily/apt
/etc/apt/apt.conf.d/50unattended-upgrades
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